Multidisciplinary Approach for Disaster Resilience and Sustainable Technologies

This article presents the author’s speculation on the desirable sustainable disaster mitigation for the era when the magnitude of natural disasters is getting greater. Nevertheless, disaster mitigation is not simple and still unclear because disaster mitigation is a preparedness against future problems and does not bring benefit immediately to people. It is difficult, therefore, for disaster mitigation project to be financially manageable under the current situations where many other issues, such as pandemics, environmental pollutions, support of higher educations, and many others require financial supports as well. Therefore, it is useful to combine the mitigation viewpoint with other points and make the disaster mitigation facilities be multi-purpose so that the overall income and expenditures may be in good balance. The use of inexpensive materials for which maintenance is easy is recommendable as well. Combination of public budgets with private funds is another good way so that disasters are mitigated by multiple barriers. This article picks up several examples of disaster mitigation in the past and today, and discusses their good points and lessons for future improvement.

Every year, heavy monsoon rains cause numerous slope failures, especially in developing countries in Asia. The authors have previously developed a simple method for predicting groundwater rise and rainfall infiltration processes on natural slopes with relatively shallow depths, based on parametric studies using the finite element method assuming a semi-infinite homogeneous slope. The vertical infiltration and lateral seepage flow were numerically modeled. In the present study, an analytical method that considers the surface flow and the subsurface flow is proposed. A recent disaster in Japan is used to validate the proposed method. The proposed method has four modules: (1) infiltration process, (2) groundwater flow in vertical and lateral directions, (3) surface water flow, and (4) slope stability assessment. The proposed model allows rainfall-induced slope failures to be simply predicted for broad areas based on an infinite homogeneous slope assumption and a simplified hydrological process. The results confirm that the proposed method can simulate actual phenomena with high accuracy.

This study aims to investigate the landslide susceptibility and resilience of the study area located in Central Taiwan, including the mountain highway and the villages in this area. The landslide susceptibility values were calculated by Logistic Regression model. By considering the core concept of resilience, the control factors were adopted and the data was collected for the study area. In order to explore the temporal behavior of landslide resilience, the population density, electricity consumption per household, and the cost of reconstruction were adopted as the indicators to establish the landslide disaster resilience model. Based on the data layers, the comprehensive linear regression model was established and used for the resilience interpretations, with suggestions on the village human mobility and the rehabilitation budget for resilience enhancement. This study can help for landslide disaster mitigation, especially for the enhancement of landslide resilience of the villages in mountain areas.

With global warming, extreme precipitation anomalies have obviously intensified during the recent 56 years in the Loess Plateau of China, which may cause water content of loess deposit increasing sometimes. The risk of seismic landslides and large-scale mudflows in the region has been increased predominantly due to the climate change. In this paper, field investigation and exploration, in-situ rainfall tests, shaking-table tests, laboratory tests and numerical analysis were carried out to study the mechanism, characteristics, and risk assessment of rainfall related seismic landslides of loess deposit. The results shown that: (1) Extreme rainfall may saturate or wet the top layer of loess slopes within 2–3 m deep so that the shear strength of the top loess decreases dramatically. Liquefaction may trigger a mudflow in the saturated loess layer and subsidence or shallow landslides may develop in the wetting loess layer under a strong earthquake. (2) If there are vertical fissures or cracks in loess deposit of slopes, rainfall water may permeate deeper soil layer to saturate the bottom layer of a slope. The saturated bottom layer may liquefy to develop a sliding surface under the effect of strong earthquakes, along which the overburden unsaturated soil deposit would slide down for a long distance. (3) The areas with high and moderate risks of climate change related seismic landslides for the Loess Plateau under the effect of earthquakes with an exceedance probability of 10% and 2% in 50 years respectively exist in the western and southeastern plateau.

Due to the trend of climate change, the extreme rainfall event could last for a long duration with a high intensity. Such extreme rainfall event is likely to trigger severe landslides and debris flows. Typhoon Kalmaegi with a high rainfall intensity and an accumulated rainfall of more than 1000 mm caused severe landslides and debris flow hazard in southern Taiwan in 2008. Typhoon Morakot with different rainfall pattern also caused extensive landslides and debris flow hazard in southern Taiwan in 2009 with an accumulated rainfall of more than 3000 mm. The study area includes five debris flow torrent basins in southern Taiwan with debris flow triggered in both events. Field investigation and numerical simulations of the debris flow were conducted on the five basins of the two typhoon events. The analysis results show that the higher accumulated rainfall leads to larger debris deposition volume, inundated area, and deposition depth, which consists with the field investigation results, and suggests a higher impact to debris flow basin. The effect of high accumulated rainfall is more significant for small basin, and no correlation was found for rainfall intensity. A linear relation can be found for deposition volume versus basin area caused by extreme events, and the data were higher compared to worldwide dataset by Marchi et al. (2018). It is suggested that the extreme events might not fit the general trend, and properly estimating debris volume related hazard would require more comprehensive consideration of the precipitation characteristics. The high accumulated rainfall induced by climate changes would cause more severe hazard and should be taken into account for mitigation strategy.

There are several possible causes of a chain of natural disasters. In this study, chain disasters based on physical causal relationships and time-series chaining are classified. Subsequently, specific chain disaster examples that occurred in the Great East Japan Earthquake Disaster were introduced. Typical examples include the destruction of reservoirs and subsequent floods, liquefaction of tailings dams and subsequent mudflow disasters, environmental pollution, land subsidence, storm surge disasters, slope disasters, and river channel blockage. To what extent should such chain disasters be considered in the design? Following the earthquake, it served as an excuse to claim that the damage was unexpected. This excuse, however, cannot be used in future if such damage is identifiable. However, it is impractical to deal with all potential hazards, an amelioration strategy is required. An anti-catastrophic perspective is essential for the design of infrastructure and hardware.

Rainfall-induced debris flows are characterised by high velocity, can be triggered by a slide and occur on established paths, usually first- or second-order drainage channels. During flow path, these phenomena entrain a strong quantity of material and water. Debris flow risk assessment and risk mitigation measure design involve forecasting spatial (susceptibility) and temporal (hazard) landslide distribution. The landslide susceptibility analysis provides the most susceptible areas to landslides and suggests where disaster protection measures are necessary to reduce the exposure of elements at risk and increase the community resilience. In this context, the paper proposes a methodology for debris flow susceptibility and hazard analysis. The methodology examines both debris flow triggering and propagation stages through two physically based models. The “Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability” (TRIGRS) model provided information about the location and initial volume of potential landslides. The “Smoothed Particle Hydrodynamics” (SPH) model, using the triggering volumes as input data, allowed for back analysis of the propagation in terms of both main pathway and depositional area. The models can be easily implemented over large areas for fast landslide risk analysis and are able to provide interesting information for the design of disaster mitigation structures.

Recently, natural disasters caused by linear precipitation zones in Japan have recurred in the same region shortly after the initial disaster. During recovery from disasters, many local governments are overwhelmed by the restoration of infrastructure in the public sector. However, since we do not know when the next disaster will occur, community outreach through soft-type measures needs to be considered and developed from the recovery stage based on the lessons learned from the initial disaster. This study explored the relationship between local government measures for community outreach and their agility, using the case of Takeo City, Saga Prefecture. The study also examines the local government’s adaptive governance in policy-making and implementing countermeasures immediately after the initial disaster.

Sand-rubber mixtures (SRMs) and gravel-rubber mixtures (GRMs) can be designed to have outstanding engineering characteristics. However, in comparison with the extensive investigations carried out on SRMs, comprehensive studies characterizing GRMs are very limited, making the index, physical, and mechanical properties of such synthetic materials mostly unknown. To facilitate the use of GRMs as fill materials in geotechnical applications, this paper provides a summary of the engineering properties of GRMs obtained from detailed laboratory tests (macro-scale response) and discrete element method (DEM) numerical investigations (micro-scale response) conducted at the University of Canterbury, New Zealand, over the past five years. The experimental investigations indicate that GRMs have adequate strength and compressibility properties for use as structural fills. Moreover, GRMs can be utilized also as filters for dampening vibrations and seismic waves, as the addition of rubber aggregates enhanced their energy absorption and dynamic properties. The DEM numerical study provides important insights into the fabric and force anisotropy, load-transfer mechanism, and strong-force network at the particle-to-particle scale, confirming the existence of three distinct behavioral zones for GRMs: rigid gravel-like, intermediate/dual, and soft rubber-like. Dual-behavior GRMs have high ductility that prevents abrupt failure and allows the mixtures to withstand larger plastic deformation before failure; they are suitable energy-absorbing structural fills for foundations and embankments as well as backfill materials for retaining structures.

Mangalore International Airport is one of the few airports in India with a tabletop runway. A tabletop runway is basically a runway located on the top of a hill with ends adjacent to steep slopes. Such airports are challenging not only from the take-off and landing points of view but also from the structural perspective. There is a need for massive cutting and filling operations to construct the runway on mountainous terrain. Stabilization of the valley slope requires slope stabilization measures in the form of retaining structures with a greater height. However, the selection of a suitable retention system for the runway expansion was quite challenging due to the vast stretches of laterite-capped hillocks which have an excellent geotechnical property in dry state and inferior properties in wet conditions. Moreover, the proposed retention system should act as a firm foundation and be able to carry the loads of aircraft, other vehicles, and seismic loading. The total height of the retention system on the runway valley side ranged between 40 and 50 m. The fill material consists of a reinforced soil structure at the top (of max. 17 m high) and bottom (of max. 13 m high) and filled slope in between. The filled slope was protected with berms, erosion control measures, and reinforced with geogrids. Special attention was given to the drainage system so as to reduce the pore water pressure behind the reinforced soil structure and to channelize runoff from the slope through appropriate drains. This paper comprises the system details of a steep reinforced soil structure along with drainage measures and erosion control measures adopted for slope stabilization for runway expansion, the design considerations, and corresponding stability checks for safety with respect to the reinforced soil structure and drainage, post-movement observations, forensic analysis of the reinforced soil structure, and redesign proposal for rehabilitation, current status of the project, and conclusions.

Ground deformation has been measured by leveling and GNSS (Global Navigation Satellite System). However, these methods are limited in the number of measurement points, and they may overlook deformation in the area in which no leveling data is available. InSAR (Interferometric Synthetic Aperture Radar) time series analysis can measure ground deformation using SAR (Synthetic Aperture Radar) satellite data, regardless of day and night or weather conditions. Case studies have been reported using this method for analyzing land deformation. However, the applicability of this method to ground deformation monitoring, including accuracy verification, has yet to be sufficiently studied. In addition, satellite observation results cannot be directly compared with leveling survey results because they distort the satellite's line of sight. In this study, we considered the method of deformation observation by performing InSAR time series analysis and selected SBAS (Small Baseline Subset)-InSAR analysis as one of the time series analysis methods to evaluate the large area of ground deformation. The vertical displacement was obtained using 2.5-D analysis, and its accuracy was verified with leveling survey results to study the applicability of SAR satellite in large-area comprehensive land deformation monitoring.

The utilization of a huge amount of waste generated from mining industries is vital for the sustainable and eco-friendly design of construction projects such as roads, embankments, and buildings. The World’s largest marble production, i.e., Rajasthan state of India is producing approximately 95% of the total marble in the country. The unscientific disposal of about 70% of marble waste (i.e., 15–20 lac tons) generated from 4000 marble mines in Rajasthan poses a major environmental threat due to its suspension in the air, increase in alkalinity of soils, water logging due to the reduction in porosity of the topsoil, etc. Marble dust (MD) has several advantageous properties such as coarser-sized particles, high shear strength (friction angle up to 44°), and non-plastic behavior which are alike with sand. Further, depletion of natural sand has forced to find suitable alternative material for its application as a geomaterial. Despite its unique characteristics of marble dust, the proper attempt has not been made to investigate the suitability of marble dust to be used alone or amendment with other additives such as bentonite (B), chemical stabilizers, etc. for geotechnical projects. The preliminary objective of present work is to find out its potential to be used in subgrade soil preparation. Detailed geotechnical investigations such as physical and engineering properties, physicochemical examination (pH and electrical conductivity) and microanalyses (mineralogical and microstructural) have been investigated in order to determine optimize the MD content for soil improvement. The secondary objective of the present work has been aimed to examine the effectiveness of marble dust amended with bentonite to be used as a landfill liner material in the substitution of sand–bentonite (S–B) mix. The geotechnical properties (i.e., swelling percentage and permeability) of MD–B mixes that are required to satisfy landfill liner design and construction are compared with S–B mixes. It is well known that the objective of engineered landfill liners is to control the migration/leakage of hazardous leachate solutions generated from dump wastes into the groundwater. Also, the interaction of liner material with hazardous leachates may lead to the alteration in the desired properties. Hence, the effects of electrolyte solutions (NaOH and NaCl) of various concentrations on the behavior of optimized MD–B mixes are investigated to confirm the efficacy and longevity potential to be used as an alternative to S–B mixes in landfills liner. Mechanisms of alteration in the properties of both mixes subjected to electrolyte concentration are brought out clearly through physicochemical and microanalyses.

In order to analyze the influence of soil anisotropy on slope stability analysis, an anisotropy yield criterion is introduced to evaluate the influence of varying shear strength on slope stability. The anisotropic characteristics of soil can be represented by the parameters n and β, which can be determined through experimental measurements. This paper constructs a complete finite element analysis framework for slope stability to accurately obtain the safety factor of slope (F_s). It is found that neglecting the anisotropy of soil will overestimate the stability of slope, especially when the slope angle (α) is small. The smaller the value of anisotropic parameter n is, the smaller F_s is. F_s will first decrease with the increase of anisotropic parameter β. When β increases to a critical value, F_s will increase with the increase of β. The greater the α is, the greater the critical value is.