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Über dieses Buch

This volume contains peer-reviewed papers from the Fourth World Landslide Forum organized by the International Consortium on Landslides (ICL), the Global Promotion Committee of the International Programme on Landslides (IPL), University of Ljubljana (UL) and Geological Survey of Slovenia in Ljubljana, Slovenia from May 29 to June 2, 2017. The complete collection of papers from the Forum is published in five full-color volumes. This third volume contains the following:

• One keynote lecture

• Landslide Monitoring and Warning: Monitoring Techniques and Technologies,

• Early Warning Systems

• Landslide Disasters and Relief: Case Studies, Emergency Measures, First Aid,

• Civil Protection Measures

• Landslide Mitigation, Remediation and Stabilization: Landslide Protection Works,

• Landslide Stabilization And Remediation Measures, Landslide Non-Structural Measures

Prof. Matjaž Mikoš is the Forum Chair of the Fourth World Landslide Forum. He is the Vice President of International Consortium on Landslides and President of the Slovenian National Platform for Disaster Risk Reduction.

Prof. Željko Arbanas is representative of Croatian Landslide Group, member of the International Consortium on Landslides. He is the Head of Geotechnical Chair at Faculty of Civil Engineering University of Rijeka, Croatia and the Assistant Editor-in-Chief of International Journal “Landslides”.<

Prof. Yueping Yin is the President of the International Consortium on Landslides and the Chairman of the Committee of Geo-Hazards Prevention of China, and the Chief Geologist of Geo-Hazard Emergency Technology, Ministry of Land and Resources, P.R. China.

Prof. Kyoji Sassa is the Founding President of the International Consortium on Landslides (ICL). He is Executive Director of ICL and the Editor-in-Chief of International Journal “Landslides” since its foundation in 2004.

IPL (International Programme on Landslides) is a programme of the ICL. The programme is managed by the IPL Global Promotion Committee including ICL and ICL supporting organizations, UNESCO, WMO, FAO, UNISDR, UNU, ICSU, WFEO, IUGS and IUGG. The IPL contributes to the United Nations International Strategy for Disaster Reduction and the ISDR-ICL Sendai Partnerships 2015–2025.

Inhaltsverzeichnis

Frontmatter

Remote Sensing Techniques in Landslide Mapping and Monitoring, Keynote Lecture

The current availability of highly developed remote sensing technologies in the field of landslide detection, mapping and monitoring allows for rapid and easily updatable data acquisitions, improving the traditional investigation capabilities, even in hazardous or inaccessible areas, while granting at the same time the safety of the operators during the fieldwork. In this work various application of remote sensing techniques for landslide detection, mapping and early warning, from spaceborne to ground-based platforms are described. Among earth observation (EO) techniques in the last decades optical and radar images are very effective tools for these implementations, since very high spatial resolution can be obtained by means of optical systems (currently in the order of magnitude of tens of centimeters), and by the new generations of synthetic aperture radar (SAR) sensors designed for interferometric applications, with revisiting times of few days. At the same time in the recent years, ground-based remote sensing techniques have undergone a significant increase of usage, thanks to their technological development and quality data improvement, in terms of spatial resolution and accuracy, fast measurement and processing times, portability and cost-effectiveness of the acquiring instruments. In this paper, the potential of space-borne imaging techniques, ground-based remote sensing methods and the effectiveness of their synergic use in the field of landslide analysis is explored by reviewing their state of the art, and by analyzing various case studies, characterized by different slope instability processes, spatial scales and emergency management phases. After assessing the advantages and limitations of the proposed methods, further fields of applications are evaluated.

Nicola Casagli, Veronica Tofani, Stefano Morelli, William Frodella, Andrea Ciampalini, Federico Raspini, Emanuele Intrieri

Landslide Monitoring and Warning

Frontmatter

Introduction: Landslide Monitoring and Warning

The Session Landslide Monitoring and Warning: Monitoring Techniques and Technologies, and Early Warning Systems, as a part of WLF4 Volume 3 Advances in Landslide Technology, collected the contributions that deal with techniques and technologies employed in landslide monitoring and establishing of early warning systems with the aims to reduce or completely eliminate landslide risk. These techniques and technologies include a wide spectra of monitoring equipment united in monitoring sensor networks including modern advanced remote sensing technologies based on satellite observations of Earth surface.

Željko Arbanas, Veronica Tofani

Multisensor Landslide Monitoring as a Challenge for Early Warning: From Process Based to Statistic Based Approaches

In the last decades, several approaches were proposed accounting for early warning systems to manage in real time the risks due to fast slope failures where important elements, such as structures, infrastructures and cultural heritage are exposed. The challenge of these approaches is to forecast the slope evolution, thus providing alert levels suitable for managing infrastructures in order to mitigate the landslide risk and reduce the “response” time for interventions. Two different strategies can be defined in this regard: an observation-based approach (OBA) and a process-based approach (PBA), this last one comprehensive of semi-empirical approaches (SEA) and a statistical-based one (SBA). At this aim, some experiments are being performed at different scales in the framework of technical applications, consulting activities and research projects managed by the Research Centre for the Geological Risk (CERI) of the University of Rome “Sapienza”. These experiments are testing different kind of sensors including interferometers, optical cams connected to Artificial Intelligence (AI) systems, extensometers, distantiometers, rock-thermometers, for detecting changes in rock properties and detecting stress-strain changes, as well as pluviometers, anemometers, hygrometers, air-thermometers, micro- or nano- accelerometers and piezometers for detecting possible triggers. The results obtained up to now encourage improving the SBA, based on data clouding, and testing them more extensively, at a national scale, by selecting test sites for experiencing their suitability for intervention strategies/procedures. These test sites will be selected along railways or roadways (in co-operation with the responsible National Agencies) where man-cut trenches could predispose to rock slides or falls that involve the infrastructures, in order to experience the suitability of SBA versus OBA approaches for early warning in the framework of lifelines management.

Francesca Bozzano, Carlo Esposito, Andrea Fantini, Matteo Fiorucci, Salvatore Martino, Paolo Mazzanti, Alberto Prestininzi, Stefano Rivellino, Alfredo Rocca, Gabriele Scarascia Mugnozza

Wireless Sensor Networks for Early Warning of Landslides: Experiences from a Decade Long Deployment

Landslides are the third largest disasters worldwide. In order to save innocent lives and property damage, a system for understanding, assessment and early warning of the landslides is highly necessary. In this work, we have designed and developed an integrated wireless sensor network system for real-time monitoring and early warning of landslides. This paper will discuss the detailed requirements and design criteria considered in the design and development of the Intelligent Wireless Probe (IWP), to capture the relevant landslide triggering parameters. The network of IWPs is used to derive the local or regional contribution of geological, hydrological, and meteorological factors towards the initiation of a potentially imminent landslide. This heterogeneous sensor system provides the capability for gathering real-time context aware data to understand the dynamic variability in landslide risk. The data from these systems are continuously transmitted to our control center for real-time data analysis to derive the possibility of an imminent landslide. Based on the knowledge discovery from these analyses a three level warning system was developed to issue real-time landslide warnings. We have deployed the complete system in Western Ghats and North Eastern Himalayas in India. The system in Munnar has proven its validity by delivering real time warnings to the community in 2009, 2011, and 2013 and continues to monitor landslides even today for the tenth year in a row. The results from the experimentation shows this system has contributed in enhancing the reliability of landslide warning, reduced false alarm rate, and provides the capability to issue warnings in local, slope and regional levels. After the success of this work, Government of India has adopted the system nationally as a result of which we have carried out a second deployment in the North Eastern Himalayas.

Maneesha Vinodini Ramesh, Divya Pullarkatt, T. H. Geethu, P. Venkat Rangan

Design and Validation of Wireless Communication Architecture for Long Term Monitoring of Landslides

Landslide prone areas are mostly in remote regions, with very limited network connectivity. Hence it is very challenging to develop a continuous monitoring system, which can deliver early warning of landslides. For developing most appropriate communication architecture we need to consider the following factors that could deliver long term monitoring and real-time early warning of landslides. The factors are: (1) frequency of data collection from spatially distributed heterogeneous sensors based on their impact on the landslide initiation (2) acceptable tolerance limit of latency for each type of data packet arrival, (3) adaptive bandwidth requirement for efficient data transfer with respect to balance energy in each wireless sensor nodes, (4) adaptive routing of the data based on the propagation, terrain and climatic effects, (5) remote maintenance using node level reconfiguration and network level reconfiguration (6) secured real time data transfer (7) scalable to multi-site deployments etc. In this work, considering all the above factors we have developed context aware heterogeneous communication architecture. We have deployed the proposed communication architecture in two landslide prone areas, where one of the architecture is functional for the last ten years. This architecture has supported in collecting real time data from more than 150 geophysical sensors in adaptive frequency rate, remote configuring the sensor sampling rate, remotely triggering new software updates, providing prioritized service delivery based on the landslide alert level, data dissemination based on the warning levels etc. We have also designed and developed a Lightweight Management Framework (LMF) for this real-time, 24/7 operational, heterogeneous network. This LMF provides the ability to incorporate different heterogeneous networks such as 802.15.4, 802.11b/g/n, VSAT, GPRS, GSM, Internet and also proprietary wireless sensor network and hardware architectures. It also handles various network failures, data corruption, packet loss, and congestion problems. In this paper, we will discuss the performance evaluation and validation results of this architecture for achieving real-time monitoring and warning of landslides.

Sangeeth Kumar, P. Venkat Rangan, Maneesha Vinodini Ramesh

Scalable, Secure, Fail Safe, and High Performance Architecture for Storage, Analysis, and Alerts in a Multi-site Landslide Monitoring System

Wireless sensor networks can be deployed in landslide prone areas to monitor various geological and weather properties to detect a possible landslide and provide early warning to local public for evacuation. Implementing and managing a system for capturing sensor data from the deployment sites and transferring to the central database for storage, analysis, retrieval and prediction is an endeavor riddled with both natural and technical challenges. The usual remoteness of the landslide prone areas result in power restrictions, bandwidth constraints and frequent connectivity issues. As the sensors and systems are exposed to constant natural elements, they are prone to frequent failures and calibration issues. Our high performance, scalable, robust, and secure system; featuring multi-site landslide data capture, replication, storage, monitoring, and processing functionalities, surmounts all these challenges effectively. The scalability and performance is achieved by real-time streaming of compressed data, in-memory processing, bulk storage, and retrieval through partitioned tables. The security is achieved through authenticating and encrypting streamed data and keeping only minimal raw data on site. The fail-safety is achieved through automated reconnection, and persisting and cross-tracking data at each processing step. Finally the high performance in analysis and alerts are achieved by series of hierarchical and temporal aggregate tables. In this paper we present the architecture and features of our landslide data system along with the performance testing statistics and related analysis. We demonstrate that our system is capable of handling data from 100 sites, each having 1000 sensors and sending data once a minute using a single cloud server.

Ramesh Guntha, Sangeeth Kumar, Balaji Hariharan

A Self-adaptive Data Acquisition Technique and Its Application in Landslide Monitoring

With aim to deal with a continuously environmental change that may be unknown at design-time, we have proposed a novel self-adaptive data acquisition method for slope instability monitoring. The developed device can automatically adjust its data output rate from very low frequency to high one to capture the high-speed process when the physical variable sensed is dramatically changing. Such technique has the potential to reduce the energy consumption, bandwidth resources and data transmission burden in some practical energy conservation monitoring applications. A preliminary application of the proposed method was successfully carried out in one slope monitoring engineering in China. Application results indicate that the suggested solution can save much more energy consumed, while maintaining the data quality of crucial information.

Xing Zhu, Qiang Xu, Xing Qi, Hanxiang Liu

A New Landslide Early Warning Technology—Escorting for Life

With vast territory, large latitude and longitude span, and complex geographical conditions, China is often subjected to various types of landslides that present unique characteristics in their forming and evolving. China suffers a lot from a great variety of geological disasters, which usually incur severe damages. As a developing country, China strongly relies on its natural resources in economic and social development. However, large-scale economic construction and resource exploitation have induced numerous landslides, making China one of the worst countries in the whole world that lie under the great damage caused by different kinds of landslides. Landslide is a major threat to the safety of people’s lives and property. The focus of landslide prevention has always been the identification of the precursor of the occurrence of landslide as well as the early warning of its occurrence towards people in the disaster area. Building on traditional landslide monitoring and early warning methods, this paper presents a set of new and effective technology. The new technology has three advantages: efficiency, cost-effective, and easy to operate. It is an effective alternative, supplement and upgrade of the traditional method, able to function with greater efficiency, speed and flexibility. Equipped with this new technology, messages concerning the upcoming landslide could be delivered to people in the first place. Meanwhile, warnings could be sent to the emergency centers across the landslide areas automatically through the synchronization within the system. In this way, people are better informed, enabling them to take the initiative to cope with the disaster before it strikes. Moreover, casualties due to delayed informing of disaster could be avoided, and losses arising in the hazard could be reduced to the minimum. Thus, it is paramount to apply and promote this new landslide early warning technology.

Hui Yu, Nianzhi Yu, Yan Wang, Lei Yu, Zhengsheng Yu

Prediction of Displacement Rates at an Active Landslide Using Joint Inversion of Multiple Time Series

This work focuses on the development of FLAME (Forecasting Landslides induced by Acceleration Meteorological Events) that analyze of the relationship between displacements and precipitations using a statistical approach in order to predict the surface displacement at active landslide. FLAME is an Impulse Response model (IR) that simulates the changes in landslide velocity by computing a transfer function between the input signal (e.g. rainfall or recharge) and the output signal (e.g. displacement). This model has been applied to forecast the displacement rates at Séchilienne (French Alps). The FLAME model is enhanced by achieving the calibration using joint inversion of multiple time series data. We consider that the displacements at two different sensors are explained by the same long-term response of the system to ground water level variations. The parameters describing the long-term response of the system are therefore identical for all sensors. The joint inversion process allows decreasing the ratio between the number of parameters to be inverted and the volume of data and is thus more statically steady. The results indicate that the models are able to reproduce the displacement pattern in general to moderate kinetic regime but not extreme kinetic regime. Our results do not give clear evidence of an improvement of the models performance with joint inversion of multiple time series of data. The reasons which could explain these inconclusive results are discussed in the paper.

Clara Lévy, Scarlett Gendrey, Séverine Bernardie, Marie-Aurélie Chanut, Aurélien Vallet, Laurent Dubois, Jean-Paul Duranthon

Time-Prediction Method of the Onset of a Rainfall-Induced Landslide Based on the Monitoring of Shear Strain and Pore Pressure

It is important to simulate the shear deformation of a slope under rainfall to predict the onset of rainfall-induced landslides. Monitoring of deformation and soil–water characteristics in a sandy slope model under artificial rainfall was conducted to establish a prediction method for shear deformation of the slope due to rainfall infiltration and the onset of a rainfall-induced landslide. A hyperbolic relationship between the shear strain and the pore pressure at the same depth was identified from the analysis of the monitored data. A time-prediction method of the shear strain in the slope was established based on the relation as follows. Regression analyses of the shear strain—the pore pressure relationship at any given time before the failure of the slope—and the time—the pore pressure relationship at the same time—were conducted first. Combining both equations produced an equation for the relationship between the time and the shear strain. The equation simulated the time variation of shear strain in the slope relatively well. Then, an equation for the relationship between the time and the inverse of the shear strain velocity was derived by differentiating the equation for the relationship between the time and the shear strain. This time-prediction method predicts the failure time relatively well, especially at deeper soil layers in the slope when the shear deformation proceeds with the smooth increase of positive pore pressure. The shear strain cannot follow rapid jumping up of the pore pressure. The results showed that the procedure described above could be applicable for the prediction of the time variation of shear deformation and the failure time of the slope.

Katsuo Sasahara

Improvement of Fukuzono’s Model for Time Prediction of an Onset of a Rainfall-Induced Landslide

Time-prediction methods based on monitoring the displacement of a slope are effective for the prevention of sediment-related disasters. Several models have been proposed to predict the failure time of a slope based on the creep theory of soil, which describes the accelerating surface displacements that precede slope failure. Fukuzono proposed an inverse-velocity method to predict the failure time. Fukuzono’s method has been widely adopted in practice because of its simplicity. His method can only be applied to the period when the surface displacement accelerates. However, the actual displacement of the slope is complicated due to the change in the rainfall intensity and the inhomogeneity of the surface layer, and it is not easy to specify the period when the surface displacement accelerates. In this study, we predicted the failure time of a sandy model slope under artificial rainfall using three methods based on Fukuzono’s model using all data from the start of monitoring onwards. The results showed that using all monitoring data results decreased the prediction accuracy and that the accuracy of the prediction improves if the period in which the acceleration of the surface displacement continuously increased could be extracted. Therefore, we extracted the period in which acceleration of the surface displacement continuously increased using a moving average method and predicted the failure time again. This resulted in improved prediction accuracy and the dispersion of the predicted results decreased. This reveals that predictions that only use the data of the period in which the acceleration of the surface displacement is positive lead to improvements in the precision. Moreover, the accuracy of the prediction improves by using regression analyses, such as the least squares method, in order to reduce the influence of velocity fluctuations of the surface displacement.

Naoki Iwata, Katsuo Sasahara, Satoshi Watanabe

A Full-Scale Model Test for Predicting Collapse Time Using Displacement of Slope Surface During Slope Cutting Work

It is important to predict an onset of slope failures or rock falls for the occupational safety because about 15–20 workers were killed by these every year in Japan. Approximately half of the victims suffered from slope failure during slope excavation construction. In this research, in order to predict the time of slope failure during an experimental testing on a full-scale model slope was conducted, and the displacements of the slope surface were monitored during the slope excavation. The surface displacements rapidly increased with the elapsed time after the excavation, and the relationship between the displacements and the elapsed time included an exponential function just before the collapsed. We validated that the time of slope failure could be predicted by the relationship between the acceleration and the velocity of the obtained slope surface displacements. However, in order to predict the time of collapse, the data was required to compute only 2 s before the collapse. Therefore, we realised the importance of providing advisory and warning signal to give workers enough time to escape the slope failures. We have discovered that by computing the inverse of velocity of slope surface displacement, advisory and warning signals can be provided 2 min before the collapse.

Nobutaka Hiraoka, Naotaka Kikkawa, Katsuo Sasahara, Kazuya Itoh, Satoshi Tamate

Classification of Microseismic Activity in an Unstable Rock Cliff

We installed a microseismic monitoring network on a 300 m high unstable rock face threatening the city of Lecco, in Northern Italy. The network is active since February 2013 and consists of 5 electromagnetic velocimeters, two of which are deployed in boreholes, two temperature sensors in air and in a shallow fracture, and a rain gauge. Regarding the detection of microseismic events, we decided to set the triggering algorithm in order to tolerate false alarms, and, as a consequence, the network has collected several thousands of events so far. Hence, it is necessary to develop an automatic processing scheme able to discard all the recorded events that are not related to the instability of the rock slope. According to the outcomes of previous studies presented in the scientific literature and to careful analysis of the collected data, we first focused on manual classification of recorded signals according to two main classes: a first one grouping events related to the stability conditions of the slope (referred to as MS and local events), and a second one clustering all disturbances (referred to as spikes, mixed event and unclassified noise). Then, we attempted to develop a classification routine in order to cluster possibly all the signals manually classified as MS events, and at the same time having few false positives. The development of classification algorithm involved analysis of parameters in both time and frequency domains, also supported by spectrograms and Radon transform computations, correlation with meteorological datasets, polarization assessment of the 3-component recordings along with principal component analysis. The algorithm we developed has proved to have a satisfactory success rate. We are now focusing on the last step of the microseismic monitoring activity that involves the localization of events related to the instability of the slope.

Diego Arosio, Mauro Boccolari, Laura Longoni, Monica Papini, Luigi Zanzi

Prediction of the Process of a Slowly Moving Loess Landslide by Electrical Resistivity Tomography

A slowly moving loess landslide along the River Danube in South Hungary was studied using electrical resistivity tomography (ERT). The aim of the research was to determine the fracture system of the study site. It seems to be the only possibility to get information about the landslide and its further evolution due to the homogeneous composition of the loess. The mass movement was expected to occur in the direction of the identified crack openings. The applicability of the ERT technique for such a supposedly dense fracture system was studied by numerical modelling and the results have been verified in the field. It was shown that it is especially important to carry out the field measurements following dry periods; otherwise the interpretation may become extremely difficult if not impossible. The dip of the fractures could not be observed and they could not be explored deeply. It was possible to map their surface projection to get the desired information about the structure of the landslide. Fracture zones could be especially well localized enabling the prediction of the positions of future rupture surfaces and thus also the delineation of the endangered zone. Although the area outside of the one that already subsided is not endangered yet, the area which has already started to move is going to break into two. Parts of the about 5 m wide blocks at the front of the landslide may fall or slide down anytime. The area below the buildings was assumed to move as one unit. Most of our predictions have been verified by the mass movements which occurred about one and half years after the measurements. The ERT method proved to be a good tool to characterize the fracture system of such a landslide area, enabling the prediction of future rupture surfaces and also delineation of the endangered area. Its use is therefore highly recommended to monitor landslides.

Sándor Szalai, Ernő Prácser, Kitti Szokoli, Ádám Tóth

The Pilot Construction of a Sensor-Based Landslide Early Warning System for Mitigating Human Damages, Republic of Korea

A sensor-based landslide early warning system in landslide highly-prone site of urban areas as a part of integrated prevention system for sediment-related disasters was suggested. The system mainly consisted of sensors, network system, and monitoring system and it had been partly revised for the improvement of its effectiveness through 3-year test-bed monitoring. The magnitude of sediment disaster (SDM) considering physical scale of the disaster and damage level was introduced for deciding the appropriate location of the system installation. The case study for Yongin-si, Republic of Korea, showed the 44 of total 1013 debris flow-hazard watersheds were estimated as the first level of SDM, the most risky area, and one of the 44 watersheds was finally selected as the system location through field investigations. In the selected 10 ha watershed, pilot construction of the system was conduct as a first step of its field application. It was hoped that the suggested system can effectively mitigate human damage by sediment-related disasters through sending landslide early warning information to residents at a landslide highly risky area directly.

Dongyeob Kim, Changwoo Lee, Choongshik Woo, Junpyo Seo, Minjeong Kang, Hyunjung Kwon

An Early Warning System of Unstable Slopes by Multi-point MEMS Tilting Sensors and Water Contents

A low-cost and simple method of monitoring rainfall-induced landslides is proposed that compared to a traditional instrumentation of inclinometers and extensometer, with the intention of developing an early-warning system. Surface tilt angles of a slope are monitored using this method, which incorporates a micro electro mechanical systems (MEMS) tilt sensor and a volumetric water content sensor. In several case studies, including a slope failure test conducted on a natural slope using artificial heavy rainfall, the system detected distinct tilt behavior in the slope in pre-failure stages. Based on these behaviors and a conservative approach, it is proposed that a precaution for slope failure be issued at a tilting rate of 0.01°/h, and warning of slope failure issued at a rate of 0.1°/h. The development of this system can occur at a significantly reduced cost (approximately one-third) compared with current and comparable monitoring methods. Given the cost reduction, slopes can be monitored at many points, resulting in detailed observation of slope behaviors, but the potentially large number of monitoring points for each slope does induce a financial restriction. Therefore, the selection of sensor positions needs to be carefully considered for an effective early warning system.

Wang Lin, Nishie Shunsaku, Uchimura Taro, Towhata Ikuo, Su Ling, Tao Shangning

Early Warning of Long Channel and Post-controlled Debris-Flow Gully in Southwest China

Closely induced by earthquake, debris flow frequently occurred and had some distinctive features, e.g. long channel and check dams controlled. In mountainous regions of Southwest China, many catastrophic events have already affect local people and became one of the main threats to lives and properties. This paper, presents an early warning method combining rain gauge, ultrasonic sensor and video recording fully adapted to debris flow gullies. A three-level early warning criteria (null, attention, and warning) has is proposed and defined in this paper. Niujuangou gully was selected as a case study to validate the approach, and to demonstrate it’s helpful to debris flow occurrences prediction.

Jian Huang

How Many Rainfall-Induced Landslides Are Detectable by a Regional Seismic Monitoring Network?

Mass wasting events occurring on the Earth’s surface may induce seismic signals, which can be recorded also at tens of kilometers from the source area. The waveforms relevant to mass wasting differ from those caused by earthquakes, because they are usually characterized by a cigar shaped waveform, duration of several tens of seconds, and low frequencies (1–10 Hz). In literature, no studies have performed a systematic analysis on comprehensive catalogues of rainfall induced landslide records at regional scale. In this work, we analyze the seismic waveforms of 1058 landslides induced by rainfall in Italy, spanning the period between 2000 and 2014. Seismic data are gathered by several European research infrastructures and collected in the European Integrated Data Archive of the Observatories and Research Facilities for European Seismology. We present preliminary results obtained from this large effort, as well as some first statistical considerations on the rainfall-triggered landslides identified within seismic records. Such analyses may provide important insights for the development and calibration of automatic landslide identification algorithms, which might be then used to verify the validity of landslide forecasting procedures based on rainfall thresholds, as well as to enhance the catalogues completeness by exploiting quantitative measures and relying not only chronicle information.

Andrea Manconi, Stefano Luigi Gariano, Velio Coviello, Fausto Guzzetti

Definition of a Fully Functional EWS Based on Rainfall Thresholds, the Case of Study of Tuscany Region

In this paper the set-up of a fully functional landslide warning system, based on rainfall thresholds, is described. This work was developed in Tuscany region (Italy), an area characterized by a heterogeneous distribution of relieves and rainfalls. The work started with the initial definition of a single set of rainfall thresholds, but it resulted to be ineffective to EWS purposes. Then a software capable to analyze several rainfall events in short time was developed, in order to overcome the problem of the subjectivity of the analyses. Once the thresholds were defined, a WebGis-based warning system was developed. This system can use both real time and forecasting rainfall data and identifies the most hazardous rainfall of each rain event. The last step of this work was the updating of the thresholds using an enhanced calibration dataset, to enhance the performances of the EWS and to account for the changes on territory and on rainfall distribution.

Ascanio Rosi, Samuele Segoni, Alessandro Battistini, Guglielmo Rossi, Filippo Catani, Nicola Casagli

ANN Based Rainfall Prediction—A Tool for Developing a Landslide Early Warning System

The study area of this work, Nilgiris district, is located in the southern state of Tamil Nadu in India. It receives heavy rainfall during South-west and North-east monsoons. The laterite soil and the presence of a large number of cut slopes make the region a landslide prone area, highly susceptible to rainfall induced landslides. This paper proposes a reliable rainfall forecast mechanism using only temporal and spatial rainfall intensity data recorded at rain gauge stations located close to the landslide risk sections in Coonoor. Several artificial neural network (ANN) based rainfall forecasting models were developed to forecast rainfall one day in advance at Coonoor. Mean square error (MSE) and correlation coefficient (CC) are considered as the performance measures to compare the forecasting ability of the ANN models. Wavelet Elman model, which had all the input predictors, emerged as the best model. Time delay neural network (TDNN) resulted in high correlation coefficient when the number of input predictors was limited. Results prove that the proposed wavelet Elman network has a forecasting accuracy better than all other ANN models and is an appropriate network to choose when the number of input predictors increases. This paper also describes the procedure adapted to develop a novel landslide early warning system based on the rainfall predicted by the best performing model and the rainfall threshold that exists for the study area. The results demonstrate the successful generation of landslide early warning messages that coincide with the landslide incidences in Coonoor.

S. Renuga Devi, P. Arulmozhivarman, C. Venkatesh

Regional Landslide Early Warning Systems: Comparison of Warning Strategies by Means of a Case Study

Two categories of landslide early warning systems can be defined as a function of the scale of analysis: local systems and regional systems. Landslide warning systems operating at regional scale are almost exclusively implemented for rainfall-induced landslides and they typically assess the probability of occurrence of landslides over appropriately-defined homogeneous alert zones using both atmospheric monitoring data and rainfall predictions. The paper focuses on such systems, by presenting a comparison of the performance of two regional landslide warning models (ReLWaM) designed considering different algorithms. The evaluation of the performance of the different models is conducted applying the EDuMaP method, which is based on the computation of a duration matrix reporting the time associated with the occurrence of landslide events in relation to warning events, in their respective classes. Two different ReLWaMs have been employed for a case study in the Campania Region (Italy), considering the six-year time frame 2010–2015. The rainfall measurements and the data on landslides were derived respectively from the TRMM project database, which reports 3-hourly rainfall data, and from the project “Franeitalia”, an inventory of Italian landslides with information retrieved from on-line journalistic sources.

Gaetano Pecoraro, Luca Piciullo, Michele Calvello

Hybrid Landslide Warning Model for Rainfall Triggered Shallow Landslides in Korean Mountain

This study uses a physically based approach to evaluate the factor of safety (FS) of the hillslope for different hydrological conditions and to prepare warning map of probable landslide occurrence using ensemble approach of in Mt. Umyeon, southern Seoul of Korea. National wide landslide inventory data was used to prepare C–D thresholds. Using 12 h rainfall a series of factor of safety distribution maps were prepared but it does not have capability to incorporate other important environmental variables. To overcome from this situation, an ensemble model was designed, in which an FS distribution of ‘alarm’ warning level was incorporated with important conditioning factors (hydrology, forest, soil and geology) using maximum entropy based machine learning algorithm. The validation was done by receiver operating curve. Which shows that ensemble model has higher accuracy than that of physically-based model alone. The ROC shows physically-based model has 65.9% accuracy whereas ensemble model has 79.6% success rate and 89.7% prediction rate. The ensemble model is a new approach to incorporating independent environmental variables and useful to planner maker.

Ananta Man Singh Pradhan, Hyo-Sub Kang, Yun-Tae Kim

Sentinel-1 Data Analysis for Landslide Detection and Mapping: First Experiences in Italy and Spain

The differential interferometric SAR (DInSAR) technique is a powerful tool to detect and monitor ground deformation. In this paper we address an important DInSAR application, which is the detection and mapping of landslides. The potential of DInSAR to detect and monitor landslides has been extensively documented in the literature, mainly using the C-band data from the European Remote Sensing (ERS-1 and -2), Envisat and Radarsat missions. A significant improvement in landslide monitoring is expected by the SAR data of the two satellites Sentinel-1A and -1B of the European Space Agency. This paper describes the authors’ first experience using Sentinel-1 for landslide monitoring. The paper describes the data processing and analysis strategy, and then illustrates some deformation measurement results obtained over Italy and Spain.

Anna Barra, Oriol Monserrat, Michele Crosetto, María Cuevas-Gonzalez, Núria Devanthéry, Guido Luzi, Bruno Crippa

Testing Sentinel-1A Data in Landslide Monitoring: A Case Study from North-Eastern Italian Pre-Alps

The main aim of this study is to test the effectiveness of Sentinel-1A Synthetic Aperture Radar (SAR) data in monitoring scarcely urbanized slopes affected by slow-moving instabilities. To this end, geological and geomorphological surveys were carried out, satellite SAR data were processed and a GPS network system was installed. The study area, named Rovegliana, is located in the North-Eastern sector of the Italian pre-Alps. Rovegliana slopes are covered by eluvial, colluvial and landslide debris deposits which are mainly affected by superficial phenomena such as creep and soil slips. In situ surveys and Advanced Differential SAR Interferometry (A-DInSAR) processing of ERS, ENVISAT and COSMO Sky-MED SAR data pointed out that the instabilities are active with constant velocities up to 10 mm/year. Only the central and eastern sectors of the area were subjected to an acceleration after an exceptional rainfall event occurred in November 2010. GPS monitoring started in October 2015 and has been implemented through four campaigns made up of high precision geodetic measures of possible soil deformations of 22 vertices of a Global Navigation Satellite System (GNSS) static network. These vertices have been connected by a network to obtain a robust system. Comparing results from historical interferometric data, GPS measurements and interferometry processing of Sentinel SAR data acquired in the period 2015–2016, make it possible to verify if Sentinel data, characterized by short revisiting time, can be used as useful tool to define the spatio-temporal evolution of the recorded instabilities, overcoming the limits of applying interferometric techniques caused by temporal decorrelation due to the presence of vegetation cover, increasing the possibility to obtain significant information about landslide dynamics from SAR data. Moreover, we expect that the high number of planned acquisitions will improve the accuracy of deformation measurements.

Giulia Tessari, Mario Floris, Vladimiro Achilli, Massimo Fabris, Andrea Menin, Michele Monego

Innovative Landslide Change Detection Monitoring: Application of Space-Borne InSAR Techniques in the Thompson River Valley, British Columbia, Canada

In this paper we present the first results from Coherent Points Analyses and Differential Stacking of RADARSAT-2 InSAR persistent scatterer interferograms covering a portion of the Thompson River valley, south of Ashcroft in British Columbia Canada. Surface displacements amounting to less than 5 cm/year are detected on landslides that are crossed by national railway infrastructure (train tracks and lock-block retaining walls). Our study shows that many landslides in the Thompson River valley have zones of displacement that are more active than others. For the portions of the North Slide, South Slide and Barnard Slide, zones of active displacement landslide can be resolved within the InSAR data acquired between 2013 and 2016. In contrast, both the Ripley Landslide and Red Hill Slide show marked variations in displacement rates related to seasonal changes in river stage and groundwater level, and compound translational-rotational sliding of coherent blocks of sediment. InSAR techniques effectively capture the surface movement detected by GPS stations, ground-based LiDAR, borehole piezometers and fibre optic installations at the Ripley Landslide test site. This successful application of Coherent Points Analysis and Differential Stacking of persistent scatterer interferograms suggests both techniques are suitable for monitoring unstable terrain in other remote settings where infrastructure, natural resources, the environment, local communities and public safety are at risk.

David Huntley, Peter Bobrowsky, Francois Charbonneau, Jeffrey Journault, Renato Macciotta, Michael Hendry

Remote Sensing Mapping and Monitoring of the Capriglio Landslide (Parma Province, Northern Italy)

In the spring of 2013, the Parma Province (Northern Italy) was affected by a large number of landslides, as a result of heavy and persistent rainfall occurred between January and April. This resulted in the triggering of about 1400 mapped landslides, which caused severe damages. In particular, on April 6th 2013, a large landslide activated in Tizzano Val Parma municipality. It stretches from an altitude of 980 m to about 630 m a.s.l., covering an area of 0.92 km2 with a total length of 3600 m. It is constituted by two main adjacent enlarging bodies with a roto-translational kinematics, channelizing downstream the Bardea Creek, forming an earth flow. The landslide crown area destroyed a 450 m-long sector of a provincial roadway, and its retrogression tendency put at risk the Capriglio and Pianestolla villages, located in the upper watershed area of the Bardea river. Moreover, the advancing toe threatened the Antria bridge, representing the “Massese” provincial roadway transect over the Bardea Creek. This work describes the main results of the landslide mapping and monitoring activities, conducted after the landslide trigger. With the aim of supporting local authorities in the hazard assessment and risk management, an integrated analysis of various remote sensing data was developed, in order to generate a multi-temporal mapping of the landslide, whose velocity reached values of several tens of meters per day in the first month, and several meters per day from early May to mid-July 2013. Satellite and aerial post-event images were analyzed, together with the results of field surveys, to accurately map the landslide extension and evolution. Moreover, on May 2013, a GB-InSAR (Ground Based Interferometric Synthetic Aperture Radar) monitoring campaign was started in order to assess displacements of the whole landslide area and to support early warning activities. The GB-InSAR acquired until December 2013.

Federica Bardi, Federico Raspini, William Frodella, Luca Lombardi, Massimiliano Nocentini, Giovanni Gigli, Stefano Morelli, Alessandro Corsini, Nicola Casagli

Monitoring the Deep-Seated Landslides by Using ALOS/PALSAR Satellite Imagery in the Disaster Area of 2009 Typhoon Morakot, Taiwan

After the catastrophic Xiaolin landslide that caused 450 casualties during the 2009 Typhoon Morakot, how to identify potential deep-seated landslides and evaluate their activities becomes an important issue for landslide hazard mitigation of the island. In the past few years, Central Geological Survey has identified 56 sites with important protected targets including village, reservoirs, roads or bridges in the disaster area of Typhoon Morakot. To better understand the activity of these potential deep-seated landslides. In this study, we used a multi-temporal InSAR model to estimate the surface deformation rate of 56 sites. The deformation rate pattern from TCP-InSAR can be compared to the LiDAR-derived DEM that it represents the long-term surface features and evaluate their activities.

Rou-Fei Chen, Chen-Yang Lee, Hsiao-Yuan Yin, Hsiao-Yu Huang, Keng-Ping Cheng, Ching-Weei Lin

Study of an Active Landslide on A16 Highway (Italy): Modeling, Monitoring and Triggering Alarm

This paper presents the preliminary results of a study carried out on an active landslide, which insists on the A16 (E842) Highway, between Campania and Puglia region (South of Italy). The area lies at the foot of a large gravitational mass, classified as “ancient landslide deposit” where a system of landslides, with different types and activity states, are present. It is characterized by the widespread presence of clayey sequences that affect the stability of the slopes looming over the highway. The site has been instrumented with a series of automated sensors, both innovative and traditional, which monitor different physical entities. Furthermore, a photogrammetry survey was carried out with a drone in order to know precisely the geometry of the slope. Once the geotechnical and hydraulic parameters were collected, a 2D finite difference numerical model (FLAC® software) of the slope was set up and a series of back analysis were carried out comparing the model results with those obtained from the monitoring database. Through these back analyses, the choice of the geotechnical parameter was refined and validated. Different physical variables and results are shown into a unique representation, in comparison with the developed model and the geological and geotechnical information. Following the trends of data, the weekly/monthly average displacements and the possible causes (heavy rainfall, raising of the water table), it is possible to study the mechanical behavior of the landslide and establish preliminary warning thresholds, which have to be verified in future. The large number of acquisitions, provided by the automated monitoring system, permits to use a statistical approach in order to identify a good reliability and increase the confidence on the results. The obtained knowledge allows for the automation of the data processing procedure and for the control of the highway stability in near real time.

Andrea Carri, Clelia Grignaffini, Andrea Segalini, Giovanna Capparelli, Pasquale Versace, Gennaro Spolverino

Experimental Landslide Monitoring Site of Poggio Baldi Landslide (Santa Sofia, N-Apennine, Italy)

On 19th March 2010, a 4 million m3 landslide was re-activated in Poggio Baldi. The landslide severely damaged some private houses, a regional road and dammed the Bidente River. The landslide can be classified as a complex movement started as a rotational slide and then evolved into an earthflow. The 2010 event was a re-activation of an ancient landslide, whose previous catastrophic activation is dated back to March 1914. Starting from 2010, the landslide has been monitored by permanent inclinometers, piezometers and extensometers. Then, from 2015 an Experimental Landslide Monitoring Site has been developed mainly for research purposes and several multi-temporal surveys have been performed by using different remote sensing techniques, such as Terrestrial Laser Scanning, Global Positioning System, Unmanned Aerial Vehicles Photogrammetry, Digital Image Correlation, Terrestrial Interferometric SAR. The Experimental Landslide Monitoring site demonstrated to be a great opportunity for both research and training purposes, as well as a place where monitoring instrument can be tested and calibrated.

Paolo Mazzanti, Francesca Bozzano, Alessandro Brunetti, Paolo Caporossi, Carlo Esposito, Gabriele Scarascia Mugnozza

Prediction of the Kostanjek Landslide Movements Based on Monitoring Results Using Random Forests Technique

Prediction of landslide movements with practical application for landslide risk mitigation is a challenge for scientists. This study presents a methodology for prediction of landslide movements using random forests, a machine learning algorithm based on regression trees. The prediction method was established based on a time series data gathered by two years of monitoring on landslide movement, groundwater level and precipitation by the Kostanjek landslide monitoring system and nearby meteorological stations in Zagreb (Croatia). Because of complex relations between precipitations and groundwater levels, the process of landslide movement prediction is divided into two separate models: (1) model for prediction of groundwater levels from precipitation data; and (2) model for prediction of landslide movements from groundwater level data. In a groundwater level prediction model, 75 parameters were used as predictors, calculated from precipitation and evapotranspiration data. In the landslide movement prediction model, 10 parameters calculated from groundwater level data were used as predictors. Model validation was performed through the prediction of groundwater levels and prediction of landslide movements for the periods from 10 to 90 days. The validation results show the capability of the model to predict the evolution of daily displacements, from predicted variations of groundwater levels, for the period up to 30 days.

Martin Krkač, Snježana Mihalić Arbanas, Željko Arbanas, Sanja Bernat Gazibara, Marin Sečanj

Remote 3D Mapping and GB-InSAR Monitoring of the Calatabiano Landslide (Southern Italy)

On October 24th 2015, following a period of heavy rainfall, a landslide triggered in the Calatabiano Municipality (Sicily Island, Southern Italy) causing the rupture of a water pipeline transect of the aqueduct supplying water to the city of Messina. This event, caused critical water shortages for several days to a large part of the city inhabitants. In order to restore the city water supplies, a provisional by-pass, consisting of three 350 m long pipes passing through the landslide area, was carried out. On November 11th 2015, a landslide monitoring system was installed, based on the combined use of advanced remote sensing techniques such as Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR), Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT). The installed monitoring system allowed to: (i) analyze the landslide geomorphological and kinematic features in order to assess the landslide residual risk; (ii) support the early warning procedures needed to ensure the safety of the personnel involved in the by-pass realization and the landslide stabilization works. In this work, the preliminary results of the monitoring activities and a 3-D mapping of the landslide area are presented.

Teresa Nolesini, William Frodella, Luca Lombardi, Massimiliano Nocentini, Federica Bardi, Emanauele Intrieri, Tommaso Carlà, Lorenzo Solari, Giulia Dotta, Federica Ferrigno, Nicola Casagli

Statistical Analysis of Displacement Rate for Definition of EW Thresholds Applied to Two Case Studies

Large rockslides are characterized by complex spatial and temporal evolution, in addition to non-linear displacement trends and the significant effects of seasonal or occasional events on their behaviour. The displacement rate and the landslide evolution are intensely influenced by many factors like lithology, structural and hydrological settings, other than meteorological and climatic factors (e.g. snowmelt and rainfall). The two investigated areas are located on the Italian Alps, Mont de La Saxe landslide affects the upper part of Valle d’Aosta region (Courmayeur) and the Ruinon landslide is sited in upper Lombardia Region (Valfurva, Santa Caterina). Both landslides are sited into a larger deep-seated gravitational slope deformation (DSGSD) and they are deeply monitored with different systems: GB-InSAR, monitoring optical targets, a GPS network and multi-parametric borehole probes. We experiment the use of statistical approach for analysis of displacement rate derived from monitoring activity to support the choice of threshold values for the management of Early Warning System, by considering also the minimization of false alarms.

Stefano Alberti, Giovanni Battista Crosta, Carlo Rivolta

Ground Based Wireless Instrumentation and Real Time Monitoring of Pakhi Landslide, Garhwal Himalayas, Uttarakhand (India)

Despite our increasing knowledge on the subject, the damage tolls due to landslides are on rise during monsoon in Indian Himalayan terrain. Therefore, the installation of a real-time monitoring system is often a cost-effective risk mitigation measure. A Landslide Observatory with wireless instrumentation for real time monitoring of ground deformation and hydrologic parameters has been established at Pakhi Landslide in Garhwal Himalayas, India. The measurement sensors include in-place inclinometers (IPI), piezometers, wire-line extensometers and an automatic weather station (AWS). The real time data is being monitored to establish warning thresholds. The annual cumulative rainfall during 2015 was 1388 mm with cumulative monsoon period (June to September 2015) rainfall of 825 mm. At the crown of landslide beyond main scarp, there is negligible displacement being the stable part. Within the main body of the landslide, it could be inferred that the colluvium, greatly weathered bedrock and their interface experience somehow greater extent of movement at different depths in comparison to the interface between greatly weathered bedrock and unweathered bedrock. A correlation between higher intensity rainfall events and displacement pattern across the inclinometer sensors is also witnessed. However, these inferences can only be established with further data analysis of later periods.

Debi Prasanna Kanungo, Anil Kumar Maletha, Manali Singh, Neelu Sharma

Terrestrial Radar Interferometry Monitoring During a Landslide Emergency 2016, Ghirone, Switzerland

In early spring 2016 an exceptionally high rock-fall activity in a slope above the Village of Ghirone, Blenio-Valley Ticino, Switzerland was observed. Constant rock-fall activity was induced by toppling movement of the very thin-layered metamorphic rock. At this time, there was no information on the actual extent and the deformation rates of the landslide instability. Due to the rock-fall and failure related risk, no instrumentation on-site was possible. Local authorities then decided setting up a monitoring campaign using terrestrial radar interferometry that does not need installations in the target area. A campaign was started in the morning of 22 March 2016. Shortly after the beginning of the measurements, the extent of the active area could be determined, showing a total affected area of 5300 m2. The displacement velocity was in the range of 0.02–0.05 m/h, showing an increasing trend. Using inverse velocity extrapolations, a failure forecast could be done pointing to a potential failure event in the late afternoon of the same day. At 16:45 UTC+1 a major part of the slope failed. It was only 1/3 of the expected volume. Landslide activity continued and a second major failure was recorded in the night. The emergency campaign ended on 24 March 2016 after the deformation was decreasing to a level without imminent threat to the village. A refined post-processing of the radar data showed that the simplified real-time processing approach was suitable for the situation. Additionally, information on the 2d direction of the landslide movement could be obtained using intensity image pixel tracking technique. Finally, maps of volume differences could be created using the interferometric baseline, showing a difference of 33,900 m3 between 22 March and a later campaign performed on 31 May 2016.

Rafael Caduff, Tazio Strozzi

Monitoring of the Stogovce Landslide Slope Movements with GEASENSE GNSS Probes, SW Slovenia

Landslide Stogovce had been triggered by an extreme precipitation event in September 2010, and destroyed a local road. Measurements in inclinometers along the newly constructed road have indicated movements in 2011 and 2016. GEASENSE GNSS probes, which were installed on the landslide body below the new road, have also measured movements in range of several cm/month in the 2012–mid 2015 period, with cumulative movement of 45 cm in this period. Depth to the slip surface was from 13 to 25 m, and groundwater occurs in most of the boreholes, approximately half meter above the slip surface. The displaced material has been also detected by the calculation of surface difference in GIS, from the 2010 and 2014 lidar DEMs. The displaced material is composed mostly of debris of fractured Upper Triassic limestone and dolomite and weathered flysch, and due to its measured movements, is still capable of being transformed into a debris flow.

Timotej Verbovšek, Marko Kočevar, Igor Benko, Matej Maček, Ana Petkovšek

DFOS Technology-Based Landslide Monitoring: The Majiagou Landslide Case Study (China)

The newly developed distributed fiber optic sensing technology (DFOS) offers a number of attractive advantages over conventional monitoring methods, such as better integration capability, higher accuracy and long-term stability, which are very suitable for the acquisition of multi-field information in slope. In this paper, the fields in slope are defined and proposed based on the engineering geological characteristics of slope. The fundamental principles of some typical DFOS technologies were introduced, and the details about the DFOS based monitoring system for the acquisition of multi-field information, including stress, temperature, seepage and deformation were described as well. In the end, a field study was conducted to investigate the effectiveness of the DFOS based system for monitoring the Majiagou landslide near Three Gorges reservoir in China. In order to acquire the deformation, temperature and seepage information deep inside the slope mass, six boreholes were set up at different altitudes to install the DFOS based inclinometers, osmotic pressure gauge, moisture meter and other optical fiber sensors. To understand the characteristics of stress field, the DFOS based stress and earth pressure gauge were installed inside the slide resistant pile. The monitoring system successfully obtained the multi-field information during the landslide evolution process. The locations with abnormal deformation could be accurately identified that corresponds to the potential sliding surfaces.

Bin Shi, Hongtao Jiang, Yijie Sun

Seismic Noise Measurements on Unstable Rock Blocks: The Case of Bismantova Rock Cliff

In this work, we tested the use of passive seismic for the characterization of potentially unstable rock blocks in the Pietra di Bismantova site, a wide slab of calcareous sandstone located in the Northern Apennines of Italy. Ambient vibrations recordings with broad-band 3-component seismometers were carried out on potentially unstable areas such as 5 rock blocks and 1 rock column located close to the top of the 100 m-high cliff. The rock blocks are also monitored by means of crackmeters. Seismic noise recordings were processed with a standard sequence and noise spectra and spectral ratios have been evaluated. Preliminary results are promising since in some cases a significant frequency peak can be observed, indicating resonance effects due to the vibration of the rock pillars. In addition, for the most favorable case, noise polarization analysis presents vibration direction values at given frequency in a limited angle range, reasonably corresponding to the direction of maximum displacement. Future investigations could address additional noise measurements and their correlation with the crackmeter datasets in order to understand possible relationship between change in resonance frequency or signal polarization and crackmeter hysteresis path. Moreover, new ambient noise surveys could be planned as a pilot investigation campaign, with the aim of designing extensometer monitoring network tuned on the most critical situations.

Diego Arosio, Alessandro Corsini, Riccardo Giusti, Luigi Zanzi

Monitoring Giant Landslide Detachment Planes in the Era of Big Data Analytics

A small mesh of sensors which monitor movements across detachment planes of the giant San Andrés Landslide on the northeastern lobe of El Hierro in the Canary Islands was established in 2013. In this paper we present the results obtained over a two year period spanning from October 2013 to October 2015. Our results demonstrate that the detachment planes are affected by sinistral strike slip displacements and subsidence of the depleted mass of the landslide. While these general trends are consistent the movements recorded at particular monitoring points differ in detail as one site is characterised by progressive strike slip and dip slip trends while another is characterised by movement pulses and reversals in the sense of movement. These findings contrast markedly with suggestions that the giant landslide is inactive and demonstrate that its reactivation is a possibility which cannot be dismissed categorically. Big data analytics have been used to identify interdependence between the recorded movements and a range of climatic and geophysical variables such as seismic data, tidal data, and geomagnetic data. We have found that the recorded movements correlate only weakly or moderately with climatic and seismic parameters but strongly to the horizontal and vertical intensity of the magnetic field. These findings are rather unexpected and we emphasise that special care must be taken in pushing the conclusions of a purely numerical analysis. The advantages of adopting a big data mindset led us to make significant improvements to the instrumental infrastructure in early 2016. These incremental improvements to the small mesh of sensors are driven partly by our desire to understand the kinematic behaviour of landslide itself and partly by our desire to explore the potential of big data analytics in geoscientific research.

Jan Blahůt, Matt Rowberry, Jan Balek, Jan Klimeš, Ivo Baroň, Stavros Meletlidis, Xavi Martí

Geophysical Model and Displacement of Active Landslide—An Example from Jastrzębia Góra Cliff (Northern Poland)

Digital photogrammetric analysis and electrical resistivity tomography (ERT) techniques were used to identify the structure of the landslide and determine its dynamics in Jastrzębia Góra cliff (northern Poland). Two photogrammetric high-resolution models were generated from airborne laser scanning data and compared. The first model came in 2010 while another in 2013. This way, the displacement of the surface of the landslide was analyzed. The differences between the grids points of digital elevation models were used for determination of vertical movements and calculation the volume of displaced rock masses. The differences were visualized as a shaded relief map. Digital model derived from airborne laser scanning can determine the precise extent of the landslide and primary and secondary scarps and provide many landslide morphometry data. The advantage of this method is the ability to filter data and therefore to eliminate the vegetation. Interpretation of relief on the digital elevation model can efficiently speed up field work and thus reduce the cost of research. In order to identify the geological structure of the cliff and the landslide structure we used geophysical method of electrical resistivity tomography. For this purpose, we made five geophysical profiles on the landslide. To detect the sliding surface and estimate the thickness of the sliding material, several transversal and longitudinal ERT profiles were collected. The resistivity images of subsurface obtained from ERT data and supported by stratigraphic and lithological data from boreholes were integrated with the information from the DEMs. As a result the geological structure of the landslide was examined and the depth of the slip zone was determined.

Mirosław Kamiński, Piotr Zientara

Hydrological Monitoring of Ash-Fall Pyroclastic Soil Mantled Slopes in Campania (Southern Italy)

Ash-fall pyroclastic deposits that mantle mountain slopes around the Mount Somma-Vesuvius (Campania, southern Italy) are frequently involved in debris flows under high-intensity and prolonged rainfall, thus representing a principal geohazard for settlements located alongside the footslope areas. In such a geomorphological framework, to understand temporal and spatial hydrological dynamics occurring into ash-fall pyroclastic soil coverings is a key factor for assessing and modelling landslide hazard as well as for setting reliable early warning system. Along with this research focus, since 2011 field monitoring activities were carried out in a test area of the Sarno Mountains to assess hillslope hydrological processes that predispose and lead to slope instability. The analysis of pressure head time series, recorded along four hydrological years (Jan 2011–Dec 2014) in the whole thickness of the ash-fall pyroclastic soil cover, showed a composite temporal variability, from the daily to the seasonal time scales, related to rainfall patterns and evapotranspiration regime as well as to unsaturated flow dynamics. Unsaturated conditions were always observed with pressure head values ranging at the annual scale from about −0.6 m to, and beyond, −20 m. Such a marked hydrological dynamics of the ash-fall pyroclastic soil covers demonstrates the relevant role of antecedent hydrological conditions in predisposing landslide triggering under a single rainfall event. Therefore, results obtained by the proposed approach can be conceived as a fundamental basis to understand hydrological processes at slope scale. Moreover they can be used to set and calibrate hydrological numerical and slope stability models for estimating rainfall thresholds triggering slope instabilities as well as to assess inherent landslide hazard.

Francesco Fusco, Pantaleone De Vita

Analysis of Hydro-meteorological Monitoring Data Collected in Different Contexts Prone to Shallow Landslides of the Oltrepò Pavese (Northern Italy)

This work presents the results of the continuous monitoring of two slopes of the Oltrepò Pavese (northern Apennines, north-western Italy), representative of different contexts usually affected by shallow landslides. The first monitored site is representative of high gradient slopes with silty soils. The second one represents slopes with low-medium slope gradient and clayey soils. Hydrological monitoring allowed to identify the responses of the soils to different rainy or dry periods, focusing in particular on the conditions which could predispose landslides triggering. As demonstrated by monitoring and by slope stability analyses through a simplified physically-based model, increase in pore water pressure during most intense rainfalls in wet periods, sometimes with development of perched water table, can promote slope instability.

Massimiliano Bordoni, Claudia Meisina, Roberto Valentino, Marco Bittelli, Silvia Chersich, Marco Musetti, Maria Giuseppina Persichillo

Field Monitoring to Measure Deformation of a Mine Waste-Dump Slope

This study surveyed and investigated the deformation of the coal waste dump slope and the natural ground slope under the waste dump at Dogye village in Samcheock city, Gangwon Province, Korea. Multiple sets of south-north tension cracks were observed at the crest of the coal waste dump slope. The size of these cracks was greater than 100 m in length, and the resulting drop head averaged 1.0–1.5 m. To investigate the behaviors of the waste dump slope and the natural slope under the waste dump, wire sensors and a rain gauge were installed at the crest of the waste dump slope, and inclinometers were installed in the natural slope of the ground under the waste dump. According to the monitoring results, the deformation at the crest of the waste dump slope steadily increased and then converged over time due to the effect of the infiltration of rain into the ground after rainfall. In addition, the horizontal deformation of the natural slope under the waste dump was affected by the accumulated precipitation. The basis of this effect is that the rate of increase of the maximum horizontal deformation tends to show increasing or convergent behavior according to the precipitation.

Young-Suk Song, Yong-Chan Cho

Monitoring Soil Movement Characteristics of an Area Subject to Land Creeping in the Republic of Korea

Land creeping in mountainous regions is a phenomenon describing sediment blocks to move downwards very slowly through a slip surface due to its geographical or geological characteristics. In Republic of Korea, there was few case of land creeping reported, but recently it often is reported because of anthropogenic impacts such as land use changes and constructions in forest sectors. The objective of the current study was to report on monitoring results of a land creeping case in Republic of Korea. The study site was located in Hadong-gun, Gyeonsangnam-do, southern part of Republic of Korea. The land creeping of 2.6 ha area was located on 200–300 m a.m.s.l. and on anorthosite of bedrock. The dominant tree species was oak trees (Quercus mongolica) in above story and bamboo trees (Phyllostachys bambusoides) in underground story. Although the land creeping event was officially reported in April 2015, it appeared to start moving in late 1990s when a reservoir for agricultural use was constructed adjacent to the area. The overflows of the reservoirs by the land creeping can cause secondary damages to downstream resident areas. Soil bulk density, particle size distribution, porosity and hardness have been periodically measured as soil physical properties of the study site. These soil factors can be used as indirect index for vegetation restoration. As a result, there were no significant differences of investigated factors except for soil hardness. Forward plans to focus on monitoring the hardness of the soil. Several 2 sets of poles were installed for monitoring on the size of two tension cracks. The length, width, and depth of tension cracks just varied through monthly measurements from July to December, 2015, but did not tend to increase or decrease. Therefore, we re-arranged and installed poles around the main scar of the land creeping in April, 2016. Now filed survey for identifying detailed geological and geographical characteristics in the area is being carried out, then specific monitoring instruments such as extensometer, groundwater level meter, ground inclinometer and so on will be installed for precise measurement from the result of the field survey.

Min-Jeng Kang, Chang-Woo Lee, Choong-shik Woo, Dong-Yeob Kim, Jun-pyo Seo, Hyun-Jung Kwon, Jae-Hyeon Park, Ki-Dae Kim

Landslide Disasters and Relief

Frontmatter

Introduction: Landslide Disasters and Relief

The Session Landslide Disasters and Relief: Case Studies, Emergency Measures, First Aid, and Civil Protection Measures, as a part of WLF4 Volume 3 Advances in Landslide Technology, gathers the main elements in the landslides disasters and relief to support landslides sustainable disaster management: emergency measures, first aid and civil protection measures.

Teuku Faisal Fathani, Željko Arbanas

Landslide Disaster and Relief Activities: A Case Study of Urban Area of Doboj City

Landslides are the one of the most common hazard in the territory of Bosnia and Herzegovina. Despite this fact, urban area of Doboj City did not threatened frequently in the past from landsliding. In the mid of May 2014, heavy rainfall between 250 and 300 mm triggered flood and activated numerous landslides in the area of Doboj City. In the frame of EU recovery program the Study of flood and landslide risk assessment for urban area of Doboj was conducted. The landslide inventory, landslide susceptibility and relative risk assessment for housing sector were done as a support for local communities for better preparedness in the future. The landslide susceptibility map for urban area of Doboj City in scale 1:5000 has provided useful information for Master Plan and related urban planning documents. Several non-structural and structural measures were proposed as a result of situation analysis and recovery needs. In this paper post landslides disaster and relief activities in the area of Doboj City, Bosnia and Herzegovina are presented.

Cvjetko Sandić, Biljana Abolmasov, Miloš Marjanović, Petar Begović, Boban Jolović

Landslide Risk Management in Uganda: A Multi-level Policy Approach

While landslides constitute a major risk in Uganda, this geomorphological hazard has been largely neglected by national and local authorities in West Uganda. Nowadays, disaster risk management is emerging in Uganda. Monitoring the on-going efforts is therefore crucial in this region. We identify the actors involved in landslide risk management in West Uganda and examine their roles and interactions by investigating both policy and practice. This paper describes a qualitative multi-policy level approach, based on extensive field work and literature on systems analysis and scalar politics. The results show that in theory, landslide risk management in this region consists of a well-structured National Policy (2010), including the establishment of horizontally structured platforms at different administrative levels and a focus on pre-disaster mitigation activities. In practice, however, the implementation is insufficient, as most platforms at local level remain dysfunctional or only meet after a disaster occurred. The dominant arena for landslide risk management remains at national level, despite the promotion of decentralisation, and the focus remains on post-disaster emergency measures, such as providing relief. At local level, bottom-up landslide risk reduction efforts are made that are disconnected from the national policy, scattered and done haphazardly. Thus, discrepancies exist between policy and practice regarding landslide risk management in West Uganda but efforts are moving gradually towards disaster risk reduction.

Jan Maes, Jean Poesen, Constanza Parra, Clovis Kabaseke, Bosco Bwambale, Kewan Mertens, Liesbet Jacobs, Olivier Dewitte, Liesbet Vranken, Astrid de Hontheim, Matthieu Kervyn

RECALL Project: Toward Resilent European Communities Against Local Landslides

In the RECALL project the Geological Survey of Slovenia (GeoZS) was a technical partner, responsible for the detailed analysis of the state of the art of reinforcement measurement, state of maintenance, priorities of investments in 4 European pilot areas which present high levels of landslide risk and interest more than 5.000 inhabitants altogether. Based on the preliminary reports a detail field inspection have been carried out for each pilot area where focus was on landslide characteristics, landslide material, triggering factors, review of damage on objects and infrastructures, collaboration with local experts and civil protection representatives. On the basis of all collected data the GeoZS prepared comprehensive report about landslide situation and provide guidelines, recommendations, priority measures (interventions) and strategies for landslide mitigation. The proposed strategy will encourage local communities to a better understanding of landslides as well make a further step in mitigation strategies.

Mateja Jemec Auflič, Tina Peternel, Špela Kumelj, Jernej Jež, Blaž Milanič, Erazem Dolžan, Giovanna Brunelli

Project BEWARE—Landslide Post-disaster Relief Activities for Local Communities in Serbia

The project—on harmonization of landslide data and training of municipalities for its monitoring, nicknamed BEWARE (BEyond landslide aWAREness) was implemented by the Geological Survey of Serbia, and the University of Belgrade Faculty of Mining and Geology. The Project partners were UNDP Office in Serbia, Ministry of Mining and Energy and Government Office for Reconstruction and Flood Relief of the Republic of Serbia. Project was funded by People of Japan. Overall aim of BEWARE project was to standardize post-event landslide database and closely involve local community of 27 municipalities affected by May 2014 flooding and landslides episode in Serbia, and prepare them to cope with catastrophic events in the future. In this paper we are presenting main BEWARE project activities and results implemented on local communities in Serbia after May 2014 event.

Biljana Abolmasov, Dobrica Damjanović, Miloš Marjanović, Ranka Stanković, Velizar Nikolić, Sandra Nedeljković, Žarko Petrović

BEWARE Multi-Device Web GIS Application for Landslides

In this paper we present BEWARE multi-device web GIS application that provides management of geospatial and attribute landslides data. Software solution is in use from July 2015 and it was continuously and successfully used for collecting field data for the project “The Harmonization of Landslide Data and training of municipalities for its monitoring: BEWARE (BEyond landslide aWAREness”). It consists of several components, two mobile applications for data collection on the field, both on-line and in off-line mode, using android devices, web GIS application for field data and web analytical tool for comprehensive statistics. Mobile application provides integration of thematic layers in the form of tile package, with field work data, as well data synchronization with GIS web portal on server geodatabase. The BEWARE is a platform for interactive landslide event reporting, analyzing and unifying landslide data and multimedia management. Development of multi-functional application was initiated in order to facilitate and improve the landslides geodatabase use and avoid building-up in areas where there is an apparent high risk of landslides. Apart from authorized users from Faculty of Mining and Geology, Geological survey and employees of Ministry of Mining and Energy of Serbia, system is used by municipalities who can record the occurrence of landslides as early notification for further inspection. Application provides several different Open Data collections for each municipality.

Nikola Vulović, Olivera Kitanović, Ranka Stanković, Dalibor Vorkapić, Ana Vulović

A Web-Based Landslide Risk Mitigation Portal

The mitigation of landslide risk to human-valued physical and non-physical assets is a fundamental component in the disaster risk management cycle. The reduction of risk can be pursued through the selection, planning and implementation of suitable mitigation measures and/or actions. The selection of the most appropriate mitigation measures is a complex process which depends on both the characteristics of the expected landslide event and the potential impacts on the physical, economic, environmental, cultural and societal human-valued assets. Each risk mitigation effort is thus markedly case- and site-specific. A web-based portal is in course of development within the Norwegian research project Klima 2050. The project is aimed at reducing the risks associated with climate changes and enhanced precipitation and flood water exposure within the built environment. The portal implements the analytic hierarchy process (AHP) for the purpose of selecting the most appropriate landslide risk mitigation measures based on user inputs and dynamic expert scoring of an extensive set of candidate mitigation measures. This paper outlines the conceptual standpoints and the present and foreseeable future structure of the portal.

Marco Uzielli, Jung Chan Choi, Bjørn G. Kalsnes

Landslide Mitigation, Remediation and Stabilization

Frontmatter

Introduction: Landslide Mitigation, Remediation and Stabilization

The Session Landslide Mitigation, Remediation and Stabilization: Landslide Protection Works, Landslide Stabilization and Remediation, and Landslide Non-structural Measures, as a part of WLF4 Volume 3 Advances in Landslide Technology, contains the contributions with the aims to present different approaches and measures used in landslide mitigation, remediation and stabilization including structural and non-structural measures with a general purpose to ensure stability of a slope against current and reasonably possible conditions in the slope.

Janko Logar, Sabatino Cuomo, Željko Arbanas

Reliability of Shear Strength Parameters for a Safe Slope Design in Highly Jointed Rock Mass

Shear strength parameters of a slope mass are of utmost concern in stability analyses. However, due to sampling difficulties, it is quite challenging to retrieve precise design parameters particularly for the slopes excavated in heavily jointed rock masses. As a matter of fact, a rough estimation of shear strength may lead to slope failures causing catastrophic events. In this paper, a repeating slope failure in highly jointed and deformed metamorphic rock mass threatening the safety of a large-scale reinforced concrete water storage tank in western Turkey is evaluated considering the reliability of shear strength parameters. On site, a series of slope stabilization works were carried out to protect the stability of existing water storage tank on the upper level. Slope stabilization by retaining pile wall failed to stop the failure at first as a consequence of poor structural design and improper assignment of shear strength parameters. Final slope stability was achieved after the placement of a permanent granular buttress. Back analyses using linear Mohr-Coulomb and non-linear Hoek-Brown failure criterion were executed to reveal the shear strength parameters of the chaotic rock mass. The maximum normal stress acting on the sliding surface was found to be around 130 kPa. Non-linear back analyses proposed a GSI value of 21 indicating a blocky and highly disturbed material. High shear strength parameters were found for the highly fractured rock mass after back analysis by the linear Mohr-Coulomb failure criterion. Eventually, it is noteworthy to mention that the shear strength parameters of a failure surface in heavily jointed rock mass are normal stress-dependent and well defined by the non-linear failure criterion.

Mutluhan Akın

A Subgrade Reaction Solution for Anchored Dowel Piles to Stabilize Landslides

This paper reports a subgrade reaction solution for anchored piles used to stabilize landslides of which the sliding layer moves with a lateral displacement decreasing linearly with depth. The developed subgrade reaction solution can deal with the case in which pile segments in both sliding and stable layers are intermediate and flexible but not rigid, and also calculate the pile response under the additional resistance required to stabilize the landslide. The proposed subgrade reaction solution calculate the response of anchored piles with no iteration. The conventional solution can be obtained from the developed subgrade reaction solution for the case in which the movement of the sliding layer is uniform with depth. Calculation of the example described in Guidelines for Design of Landslide Control Steel Pipe Piles (JLS 2003) shows same pile response can be obtained by the proposed subgrade reaction solution and the conventional subgrade reaction solution in which an iteration process is necessary to obtain the results.

Fei Cai

Modelling the Performance of a Reinforced Natural Slope in Niscemi (Italy)

In Mediterranean areas the behaviour of slopes depends on seasonal factors such as initial conditions of pore water pressures and time-dependent conductivity of soil. This is the case for natural and engineered slopes. The paper analyses a case study of Southern Italy, where a slope about to an historical centre was improved through the reshaping of ground surface and the introduction of both coarse-grained material and geosynthetics reinforcements. FEM seepage analysis and limit equilibrium slope stability analysis were performed to understand the failure mechanism of the natural slope and performance of the engineered slope. The numerical results highlight the important role of soil unsaturated conditions in both the slope configurations.

Sabatino Cuomo, Lorenzo Frigo, Lorenzo Ciorciari

Modelling the Propagation of Debris Avalanches in Presence of Obstacles

Landslide propagation modelling is an important issue in engineering-based procedures for susceptibility and hazard analysis. The paper deals with debris avalanches, which develop along open slopes with nearly constant inclination and may propagate over large distances. In particular, the paper investigates the effect of different combinations of artificial obstacles on landslide run-out, deposition heights and thicknesses of soil eroded along the landslide path. Among the several numerical techniques available to this purpose, Smooth Particle Hydrodynamic (SPH) is used since it is a convenient tool for reasonable computational times and accurate description of the main kinematic quantities such as heights and velocities of the mobilised volumes. A frictional rheological model is used, and also the role of time-space variable pore water pressures is considered. The numerical results are discussed to individuate the changes induced by obstacles in landslide dynamics and to discuss the feasibility of such typology of intervention in steep slopes.

Sabatino Cuomo, Leonardo Cascini, Manuel Pastor, Stefano Petrosino

Analysis of Rockfall Stop-Distance Factors with CRSP-3D in Volcanic Talus

The costs associated with rockfall risk are high. Many resources are invested in rock slope maintenance and stabilization, and protection measures to reduce rockfall hazards on transport infrastructures. However, few studies aim to evaluate the relative influence of the different factors (geometrical and material properties) affecting falling rock trajectories and the efficiency (retention capacity) of catchment areas. Numerous factors influence both the characteristics of rockfall motion, and their impact and stop-distance. Ritchie’s empirical research (1963) was the first to identify these characteristics and determine the expected impact distance of rockfalls depending on slope geometry. Later studies showed that Ritchie’s results were not as conservative as previously thought, and also that it was hard to apply his ditches on roadways due to their excessive depth (dangerous for vehicles) and width (expensive construction and maintenance). The Ritchie ditch has therefore been improved by computer simulation programs, and the proposed use of concrete walls or fences at the edge of the road. Optimization of the catchment area geometry requires systematic and quantitative analysis of the effect of each factor on rock stop-distance through application of a simulation model. With this aim, this study applies a CRSP 3D computer simulation model (Colorado DoT, USA) considering 75 different configurations of slope-ditch geometries, 4 types of materials and 9 size and shape combinations of falling rocks. In all we examined 270 different cases for hard rock and 180 for soft rock. A statistical analysis was performed with the simulated rock stop-distances to assess the different variables affecting rockfall motion.

Jorge Yepes, Cándida García-González, Miguel Angel Franesqui

Rockfall Hazard Mitigation Using Ditch Charts Modeled with CRSP-3D

Rockfalls on roadways are a serious hazard to users. Many resources are invested in rock slope maintenance and measures of stabilization and protection to mitigate the risk. Catchment areas (ditches) are one of the least expensive and most effective protective measures to contain and restrict rockfall onto roadways. While their effectiveness depends directly on their design criteria, previous studies have mainly been limited and based on empirical studies. Ritchie (Evaluation of rockfall and its control., pp. 13–28, 1963) drew up the first design charts and tables, establishing the impact distance of a rockfall as a function of the slope height and steepness. Though his work is still accepted, it has some significant limitations: his design relies on such a deep, steeply sloped ditch that it reduces road safety, restricts the slope geometry and complicates the maintenance of these catchment areas. Pierson et al. (Rockfall Catchment area design guide. Final Report SPR-3(032), 2001) created new graphic charts based on real rockfall tests carried out on different slope-ditch arrangements, but their research presents certain drawbacks: the examined situations are limited to a specific type of material, shape and possible rock size, the dimensions proposed to obtain certain percentages of rockfall retention are very large and, in most cases, the costs are unreasonably high. This present research complements previous studies by using a CRSP 3D computer simulation model (Colorado DoT, USA) and analyzing a wider number of slope-ditch arrangements and input parameters: (A) 5 talus heights, 5 slope gradients and V-ditches with 3 foreslopes. The highest slopes (≥18 m) have an intermediate 1 m bench at 12 m height. (B) Different kinds of materials are handled: 4 bedrock lithologies, two of them for the slope (hard rock and soft rock), one for the ditch (concrete) and the other for the road pavement (asphalt). The properties of these materials (density, elasticity, roughness) have been established according to the CRSP 3D methodology and adapted to previous empirical knowledge of each material. (C) A wide array of blocks was studied considering various possible combinations of geometries (cube, cylinder, sphere) and sizes (0.31, 0.62 and 0.94 m). A total number of 270 different cases for hard rock and 180 for soft rock have been evaluated. (D) Rocks are released randomly (along the whole slope) and the initial velocity is zero. As a result of the numerical analysis, a set of practitioner-friendly charts were drawn up, not only for infrastructure planning and design tasks, but also to evaluate existing catchment area effectiveness and to reduce rockfall hazard. The proposed design charts offer an estimation of the dimensions required for the ditch, depending on the relation between the optimal stop distance and the cumulative percentage retained along the trajectory, satisfying specific retention requirements (95%).

Jorge Yepes, Cándida García-González, Miguel Angel Franesqui

High Geogrid-Reinforced Slopes as Flexible Solution for Problematic Steep Terrain: Trieben-Sunk Project, Austria

A large-scale construction project was implemented between June 2006 and September 2008 to reroute the B114 mountainside link road between Trieben and Sunk in Austria. In addition to comprehensive drainage and anchorage measures, the works included the extensive use of extra-steep, geosynthetic-reinforced slope structures to build the route and stabilize critical slip-prone slopes. This paper presents a technically expedient and practically feasible solution for the use of geosynthetic-reinforced retaining structures on projects subject to extremely difficult geotechnical and topographical conditions. Following a description of the geotechnical situation and associated problems, the procedure for dimensioning the geogrid-reinforced structures and practical aspects of the site operations are outlined, explained and discussed.

Oliver Detert, Pierpaolo Fantini

Implementation of a Flexible Wire Net Dam for Controlling Debris Flow in a Small Mountain Torrent

Debris flow is recognized as a major natural hazard in torrent landscape over the world. Various types of control structures have been employed to capture debris flow in mountain torrents of Korea. In this study, flexible wire net dam was newly designed and implemented to retain debris flow on a small, steep mountain torrent. The dam consists of a flexible net panel, wire anchors and supporting rods to dissipate the energy of debris flow. A 500 mm × 500 mm wire panel was designed to endure the impacts of debris sediments, regarding the characteristics of streambed materials on upstream torrents. The plane stresses induced by debris impacts were uniformly distributed over the panel and subjected to the wire anchors installed in river banks. The anchors were specially designed to absorb the kinetic energy of sediment movement. Supporting rods were anchored into streambed and keep the wire panel against the sediment-induced force. Designed dam was implemented in average slope of 35° torrent of Mt. Gwanak in Seoul, Korea. The dam has a 15 m bottom width and 3 m height. Design load was estimated from the size and density of stony debris materials placed in upstream torrents. A 95-percentile diameter of sediment materials (D95) was 0.5 m in size. Maximum force acting on wire net was estimated to be 14.81 kN/m for design purpose. The flexible wire net dam has well-designed and installed in a site for preventing debris flow movement. The dam can be constructed without disturbing the stream environment and with ease, so it has environmental benefit and safety performance by reducing dangerous works for construction.

Sangjun Im, Seungyoub Yi, Song Eu

Flexible Barriers Composed of High-Strength Steel Nets, as a Solution to the Near Surface Slides

On steep slopes, a number of different gravity driven hazards (shallow slide, rockfall, snow slides) threaten the safety of people and infrastructures. Saturated layers of soil can form shallow slides, which can trigger spontaneously and flow at relatively high speeds of up to 10 m/s (35 km/h). If a shallow slide flows into a river channel, this can spark a debris flow. Depending on the flow speed and volume of the displaced material, shallow slides can have a destructive impact, disrupting traffic routes and causing major damage to buildings. The climate as a risk factor with an expected increase in heavy rainfall in lower case alpine regions and more frequent winter storms, coupled with the fact that the snow line is moving ever higher, in the future the environment will contain more water to potentially trigger shallow slides. Meteorologists are predicting that the likelihood of extreme rainfall events will also rise across the world (global climate change). Suitable protective measures are designed to secure roads and rail lines against shallow slides. Exposed buildings must also be protected against these near surface landslips. The conventional protective measures consist in erecting structures to divert the landslide -dams or reinforced mountainside walls- requires a huge amount of constructing work. Particularly in steep terrain alongside roads and rail lines, measures like this can only be taken in certain circumstances. Flexible shallow slide barriers have been proven to retain mixtures of water and solids, such as mudslides and shallow slides, even in the event of multiple impacts. The barriers can be installed with a low outlay of material and man hours, greatly reducing costs and construction time. Combined shallow slide and rockfall hazards are a common situation for unstable slopes: the steep flanks of landslide slopes are often sources of rockfalls. Moreover, the erosive action of a shallow slide can remove soil and vegetation cover down to the underlying bedrock, exposing further potential for rockfall events. In this contribution we also discuss the challenges in designing protection measures that can cope with both shallow slides and rockfalls, each one characterized by different load cases. Shallow slides impact with spreading pressures that load gradually, while rockfalls impact punctually with high velocities. We discuss the findings of number of full scale experiments investigating different load case; a finite element simulation software FARO used in the design of flexible wire protection systems will be presented.

Corinna Wendeler, Volker Leonhardt, Roberto Luis

Synthetic Water Repellent Soils for Slope Stabilization

Water repellent soils, or non-wettable soils, are described as having delayed wetting of the soil surface and water infiltration, and have been studied by soil scientists and agriculturists for decades. Soil water repellency induced by wildfire is believed to be a major trigger of post-fire debris flows, by changing the hydrological characteristics of the slopes, the rainfall infiltration is delayed, leading to the increased surface runoff and eventual soil mass movement. On the other hand, the potential applications of water repellent soils in the field of slope engineering have also been recognized recently. Due to their ability to inhibit water infiltration while remaining gas permeable, water repellent soils are considered to be promising fill materials and impermeable barriers. Soil water repellency is widely observed to occur in nature because of wildfire and organic matter, while in the laboratory, it can be induced by coating the soil particles with low surface energy substances such as silane compounds. An advantage of synthetic water repellent soils is that the level of water repellency is adjustable (from very wettable to extremely water repellent), and therefore the rate of infiltration can be controlled in various scenarios. Since intense rainfall and subsequent infiltration significantly contribute to fill and natural slope failures, water repellent soils have proved to be effective in hindering the infiltration and generation of excess pore pressure and therefore could increase the overall factor of safety during rainstorms. Landfill cover is another potential application of water repellent soils.

Shuang Zheng, Sérgio D. N. Lourenço, Peter J. Cleall, Stuart W. Millis, Angel K. Y. Ng, Ting Fong May Chui

Destructive Influence of Technogenic Factors and Precipitations on Landslide Support Structure

The investigated landslide occurred after mass excavation at the toe of the slope due to construction of an aqua park and heavy rainfall in November 2014. The induced slope instability affected the only road linking the village of Gorni Voden with the town of Asenovgrad. Immediately after the landslide occurrence an engineering-geological site investigation had been carried out. It was followed by proposal for remediation measures. The landslide has an elongated shape with a maximum width of up to 60 m, length 140 m and area of approximately 8000 m2. The volume is above 20,000 m3. The damaged length of the road was 35 m. The investigation established the geological composition of the slope, key elements of the landslide, its mechanism, physical and engineering properties of the soil and the groundwater conditions. The reinforcement design consists of anchored pile retaining wall and drainage system. Due to the delay in construction, during the following warm and rainy winter the landslide increased its area more than two times. Subsequently, after the anchored pile retaining walls were constructed, the builder of the new aqua park made a new deep excavation downslope from the reconstructed road section. This excavation destabilized the landslide once again leading to cracks formation on the slope and increasing the depth of the sliding surface. The landslide body has been saturated through the open cracks by the following rainfall, soil consistency has been changed and the shear strength has decreased. The landslide process has progressed upwards and the new sliding surface reached the anchored pile retaining wall and compromised it locally. This paper discusses the remediation design proposed after the landslide occurrence, its implementation and the factors influencing the consequent structural damages on retaining wall due to loss of overall stability.

Georgi Frangov, Hristina Zayakova, Stefan Frangov

Collapse and Remediation of Vrhole Landslide

The first signs of instability of a 20 m high cut, which was executed during the construction of Ljubljana—Maribor motorway in the nighties, were observed in 2010. On the bottom of the cut, next to the shoulder of the motorway, there was distinguished ground heaving while some 2 m deep cracks appeared on the body of the sliding mass. Approximately 100 m wide landslide was formed endangering the traffic on the motorway. A comprehensive site investigation was carried out in 2011, which included measurement of movements and the installation of the set of piezometers and inclinometers. Based on the contemporaneous state of the landslide and the results of site investigation the design of the remediation was carried out. The design, which comprised a 100 m long pile wall and deep drainage, was never applied in practice. During the night in the spring in 2013 the landslide collapsed and the debris covered all three lanes of the motorway in Ljubljana direction. Fortunately, the maintenance services were quickly informed and the motorway was immediately closed so that there was no material or human loss resulting from the landslide. The new design of the remedial measures, which conformed to the newly developed boundary conditions, was carried out in 2014. The new design comprised deep drainage and the gravity wall, so that the landslide was fully stabilized during the same year. Geological conditions, the ground model, causes of instability and remedial measures are presented in the paper.

Saša Galuf, Vojkan Jovičić

Interaction of Landslide with Critical Infrastructure

The interaction of natural hazards, namely landslides, with critical infrastructure is still very actual problem especially from the new demands on such transport infrastructure. Paper describes very sensitive example of such interaction, as new constructed motorway D8 from Prague to Dresden is passing the area with old tertiary volcanic activity, generally prone to landslides. At the end of excavation for motorway lanes—in two different levels—large landslide occurred immediately after for this area extremely heavy rainfalls at the beginning of June 2013. The evaluation of landslide reasons, proposed remediation measures are therefore described in details, allowing to guarantee full operation of this motorway at the end of 2016.

Daniel Jirásko, Ivan Vaníček, Martin Vaníček

The 10-Mile Slide and Response of a Retaining Wall to Its Continuous Deformation

The 10-mile Slide has a volume of about 750,000 m3 and is sliding on a through-going shear surface at velocities up to 10 mm/day. Its importance is associated with the location of a highway and a railway line within its boundaries. Risks posed to the railway were managed through monitoring and running patrols in front of trains, and a pile retaining wall was installed immediately downslope from the tracks to prevent deformations caused by loosening of materials associated with the slope deformations and delay the retrogression of the landslide. Displacement measurements of the piles have monitored the response of the wall as the landslide retrogressed upslope from the railway track. This paper presents a brief description of the 10-mile Slide geologic context, its kinematics, mechanism, and evolution followed by a presentation of measured response of the retaining wall as the landside retrogressed.

Renato Macciotta, Tommaso Carlà, Michael Hendry, Trevor Evans, Tom Edwards, Paolo Farina, Nicola Casagli

Inadvertent Engineered Activation of Utiku Landslide, New Zealand

New Zealand’s North Island Main Trunk railway and State Highway 1 cross the Utiku landslide in central North Island. When we began a research project on slow-moving blockslides, we assumed that Utiku landslide was typical of over a thousand other blockslides in the Neogene sedimentary rocks. Its relationship with a national transport corridor enabled intensive engineering geological investigation. It became obvious near the close of our study, that the landslide’s activity through the 1960s to the 1970s was an extreme anomaly in the geological record, and coincided with intensive engineering work on both the road and rail. By then, we knew that Utiku landslide was very sensitive to changes in environmental conditions. This led us to examine the sequence of engineering work on the landslide. Utiku landslide initiated prehistorically by erosion by Hautapu River, when incision intercepted a weak clay seam. Further incision in recent decades released the rock mass further down-dip, allowing lateral propagation of the landslide. Hautapu River joins Rangitikei River 100 m downstream of the landslide toe. The bed of Rangitikei River downstream of the junction is a source of gravel for construction and maintenance of the transport corridor. The Rangitikei River bed has been lowered, leading to loss of gravel from the bed of Hautapu River, which is now a bedrock channel. This accounts for the recent landslide propagation, and raised the question of where the gravel was being used. The railway crosses Utiku landslide on an embankment. As the rails move with the landslide, the offsets are realigned and the railway is re-leveled using the gravel. The railway has always crossed Utiku landslide on an embankment, so the head of Utiku landslide has carried some surcharge since before 1904, but the surcharge has increased each time the railway has been re-leveled. A most extensive repair was shortly after 1960. State Highway 1 also crosses Utiku landslide; its realignment in the 1960s involved cuts to the north and south of the landslide and fill was placed on the landslide. The total surcharge may now add about 10% to the landslide mass. Engineering work on Utiku landslide has loaded the head and unloaded the toe of a landslide that is very sensitive to environmental changes; the predictable consequences continue to affect the transport corridor.

Mauri J. McSaveney, Christopher I. Massey

Landslide Remediation Between Kvaternikova and Divoselska Street in Zagreb

On the slope between Kvaternikova and Divoselska street in Zagreb landslides have been activated after heavy snowfall in mid-January 2013 that threaten surrounding residential buildings and water, gas and sewage infrastructure in Kvaternikova Street. According to residents whose houses were threatened by landslides first cracks on slope surface were noticed in the summer of 2012 after a long dry period. Unfavorable weather conditions in 2013, snow melting and rain caused the progression of sliding and on the landslide surface it created loosened soil material with high water content. Accessing the landslide with heavier machinery was not possible and in accordance with such a situation on the site and the available technology emergency measures were implemented that included the drain trenches and driven wooden piles from local wood. Implemented emergency measures prevented the collapse of road, sewage, gas and water supply as well as sliding and launching larger landslide mass. In the next phase detailed design were made in which remediation of the entire landslide was planned. For the purposes of the design for landslide remediation insight into the existing geological maps and earlier investigations was made and geotechnical investigations were conducted. Final landslide remediation measures included the construction of retaining wall with strand anchors and foundation on piles along the road, shifting soil masses on the slope, gabion wall in the lower part of the slope, construction of drain trenches and planting vegetation. In order to control performance of landslide remediation and record side effects that require additional remedial measures, monitoring was carried out. In this article are presented all the phases of the landslide remediation in chronological order from the investigation works, emergency remedial measures, detailed design documents, construction phase and monitoring.

Katarina Ravnjak, Goran Grget, Leo Matešić, Marko Kaić

Rain-Induced Failure of Railway Embankment at Double Track Lane at Bogor and Its Countermeasure

Slope failure occurred in a 100-m railway embankment between Jakarta and Bogor City during a heavy rainfall period in November 2012, causing disconnection of one railway line and damaged several houses below the railway embankment. Sub-surface investigations and numerical analyses were carried out to evaluate hydrological and geotechnical conditions of the embankment for the purpose of an immediate embankment reconstruction and a long-term stabilization. The geotechnical drilling data show that a soft clayey silt layer, acting as the slip zone, exists at the top of a volcanic rock layer. The groundwater monitoring data show that a shallow groundwater table exists in the upper and the middle parts of the embankment slope. Based on the geotechnical data, the embankment was then reconstructed using woven geotextile reinforcement. However, the numerical analysis indicates the safety factor of the reconstructed embankment was still below the required safety factor under a low train load and a slow train speed. Under a time and space constraints, one line of bored piles of 1 m in diameter was selected to increase the embankment stability. The numerical analysis showed that the bored pile reinforcement was effective to increase the safety factor of the embankment slope to more than 1.3 under a train load of 18 tonnes with a maximum speed of 80 km/h. The inclinometer data also suggest the effectiveness of this bored pile for long-term stabilisation of the new embankment.

Adrin Tohari, Arifan Jaya Syahbana

Landslide Stabilization in Building Practice: Methodology and Case Study from Autonomic Republic of Crimea

Within the framework of the IPL Project No 153 “Landslide protection structures and their development in the Autonomous Republic of the Crimea, Ukraine (ARCU)” the information about landslide protection structures and measures, prospects of their development in the ARCU was collected and structured; the target data base was created. In specific Crimean conditions driven piles are not used, as a rule, due to general spread of soils with high content of rock and hard rock inclusions presented by argillites and siltstones with sandstone layers. Bored piles have been widely used since 1968 on the Crimean landslide slopes. They allow successful fixation of landslides with the thickness of 15–20 m. One of the most efficient solutions for landslide protection is the retaining constructions based on the short underground piles (SUP). They are shortened bored piles, immersed below the slide surface on the calculated value and output above it at a distance providing overlapping of slipping soils. In the process of experimental work there appeared the need to choose the optimal testing mode. In summary, the above results of IPL Project No 153 were used for design structure No 1 in Gurzuf town and landslide protection structures No 2 in Koreiz town of landslide protection structures based on SUP’s technology. The seismicity of the construction sites is 8 points due to Medvedev–Sponheuer–Karnik seismic scale (MSK-64). At present all the building structures are commissioned in ARCU.

Oleksander Trofymchuk, Iurii Kaliukh, Viktoriia Berchun

Monitoring and Assessment of Remedial Measures in Closed Open Cast Mine

The excavated open cast mine Chabarovice, particularly the part of it with local name Rabenov, has been investigated and monitored by the Czech Technical University since 1998 because of problems connected with different types of instabilities. Complicated geotechnical conditions, extreme heterogeneity and artesian ground water of the origin site together with the conditions modified by open cast mining were the main reasons of land sliding. Stability analyses made by the Department of Geotechnics were focused on final slopes of the mine together with the supporting waste dump and they were based on analyses of 3-D deformation monitoring in instrumented boreholes and pore water pressure sensing. The Department has contributed to development of several types of remedial measures as drainage works, re-shaping, stabilizing embankment assessment, discontinuous anchored pile wall. The group of experts of the Department was asked to provide risk analysis of the final version of the design of the measures of the last but not stable Rabenov part of the mine. The results of the monitoring with results of analyses will be presented in the paper. Development of displacements on the site demonstrated partly different behavior than expected at the design stage and it approved concerns stated in our risk analysis. These events are described and discussed in the paper. There were successfully tested different applications of fiber optics deformation monitoring developed in before research and development projects, there. Continuous high resolution fiber optic monitoring system was modified for a new research focused on a group of churches in eastern Bohemia.

Jan Zalesky, Kristyna Capova

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