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This book comprises the proceedings of the 1st International Symposium on Construction Resources for Environmentally Sustainable Technologies. The contents of this volume focus on issues related to natural and man-made disasters, and discuss solutions through the use of alternative resources, towards building a sustainable and resilient society from geotechnical perspectives. Some of the themes covered include recycled materials in geotechnical constructions, management and utilization of disaster wastes, climate change independent natural disasters, socio-economic and environmental aspects in sustainable construction, physical and numerical modelling of disaster mitigation techniques, etc. This book will be beneficial to researchers, practitioners, and policy-makers alike.

### A Review of Data on Biodegradable Resin Concrete and Future Tasks

Mariko Suzuki, Kazuya Inoue, Toshinori Kawabata

### California Bearing Ratio of a Cohesive Soil Reinforced with Waste Tyre Fibres

This paper investigates the influence of waste tyre fibres on the geotechnical properties of clayey soil used as a subgrade material. Laboratory California bearing ratio (CBR) tests were conducted for the unsoaked condition as a measurement of pavement performance under the normal rainfall. Three types of tyre fibres as TFA, TFB and TFC used in the present study were mixed in a proportion of 0.25, 0.5, 0.75 and 1% by dry mass of clayey soil. In each test, the specimen was prepared in accordance with the compaction characteristics achieved from the modified compaction energy. The test results reported that the compaction characteristics of cohesive soil were getting increased with an increase in fibre content. In general, regardless of the fibre size, the CBR values get increased with an increase in fibre content. The experimental results showed that clayey soil achieves five times higher CBR value for the addition of 0.75% TFC. From the test results, it can be concluded that the use of waste tyre fibres considerably reduces the pavement thickness and hence reduces the construction cost.

Mohit K. Mistry, Ankit Vasoya, Shruti J. Shukla, Chandresh H. Solanki, Sanjay Kumar Shukla

### Effect of Installed Geotextile/Polyester and Biodegradable Materials for Dewatering Soft Clay

Geotextile, polyester, and biodegradable (paper) materials are prominent in dewatering slurry sludge/sediment and soft clay. This is because of their high permissibility properties. The purpose of this study is to increase the efficiency of the dewatering setup by inserting geotextiles materials and paper into a dewatering setup with woven geotextile on the base before filling with soft clay, respectively. In this study, simple dewatering system by pouring soft clay into a 0.0135 m3 dewatering box and tube with the installation of geotextile material and paper at 100 mm spacing to promote the dewatering setup efficiency is investigated. A soft clay of 200% water content was poured into the boxes and thereafter, geotextiles and paper were installed separately in the 0.0135 m3 dewatering setup. The test results show that string polyester material in a tube dewatering setup can dewater the slurry clay below its liquid limit (142%) within a week, while box setup reduces the slurry clay water content its liquid limit after 14 days. Tube dewatering setup is more effective because it contains small volume of slurry clay. The suction test results show that the dewatering performance of a dewatering setup is subject to the dewatering days and the amount of void that can be reduce by the dewatering setup.

Flemmy Samuel Oye, Kiyoshi Omine, Zicheng Zhang

### Effect of Moisture Content on Particle Breakage of Recycled Concrete Aggregates During Compaction

Construction and rehabilitation of roads demand a large volume of crushed rock which is used in granular layers of the road pavement. If recycled concrete aggregates which are extracted from construction and demolition waste satisfy all the engineering aspects of the material, then their use not only reduces the depletion of natural resources but also effectively helps to utilize the waste. However, the use of recycled concrete aggregate (RCA) as a granular material highly depends upon its performance under field loading conditions. The particle breakage is one of the important factors that affects the performance of recycled concrete aggregate, especially in long-term pavement performance. However, prior to long-term performance evaluation of RCA, the particle breakage during compaction process shall be estimated. In this regard, the present study focuses on the particle breakage of recycled concrete aggregate during compaction. Energy equivalent to modified proctor is used to investigate the particle breakage of recycled concrete aggregates. Moreover, influence of moisture content on the particle breakage during compaction is also studied. Results indicated that particle breakage is affected by variation in moisture content. With increase in moisture content, the particle breakage decreases.

Syed Kamran H. Shah, Taro Uchimura, Ken Kawamoto

### Environmental Implications of the Recycling of End-of-Life Tires in Seismic Isolation Foundation Systems

The extensive generation of end-of-life (ELT) tires worldwide has resulted in adverse environmental effects and threats to public health and safety including tire fires and leaching of contaminants into the soil environment, groundwater, and surface water. It is becoming imperative to investigate more sustainable and large-scale opportunities for the reuse of ELTs. One novel engineering solution is their reuse in structures with enhanced seismic resilience. This is particularly important in countries such as New Zealand and Japan where past earthquakes have caused widespread damage and socioeconomic loss. Research is being carried out to investigate a seismic-resilient engineered foundation-soil system for low-to-medium-density low-rise residential housing composed of a layer of granulated tire rubber (GTR) and gravel, and a flexible rubber–concrete raft foundation. It is essential to ensure that such innovations do not result in long-term negative impacts on the environment as tires contain hazardous compounds used in their manufacturing and the steel fiber within the tires can leach heavy metals (e.g., zinc, manganese, lead, cadmium). Preliminary batch leaching tests undertaken on (1) GTR and (2) GTR: gravel mixtures (20–40% rubber content by volume) indicated leaching of calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K) which was contributed to the gravel and low levels of zinc (Zn), which were attributed to the tires.

Laura Banasiak, Gabriele Chiaro, Alessandro Palermo, Gabriele Granello

### Estimating Landfill Height Considering the Heterogeneous Physical Property of Dredging Soil as Reclamation Material

When pump-dredged clays are discharged into a disposal pond in the sea, soil particles are initially suspending in the water and gradually settles to the sea bottom. According to subsequent discharging, a new sediment is piled on the top surface of the sediment already formed, and the sediment already formed consolidate due to the own weight of new one over a long period of time. To predict the capacity of such disposal pond, it is important to estimate the time-dependent volume change of dredged clays during the reclamation process. In order to estimate the high accuracy the time when the current disposal pond will be full, it is necessary to use the reclamation analysis developed based on a general consolidation theory. In this paper, targeting the S-3 area of Shinmoji-Oki disposal pond project currently underway, we assume that the model of dredged clay deposited in the future on the ground model can be identified by back analysis. Predictive analysis is performed using consolidation parameters assumed from the physical properties of the collected clay, and different filling periods are confirmed due to differences in the physical properties. Furthermore, we also propose a method to improve the prediction accuracy.

Yoshihisa Sugimura, Yasuhiro Sega, Masaaki Katagiri, Katsuhide Nishizono

### Evaluation for Effective Use of Dredged Soil as Containment Dikes of Disposal Pond

An extra fill on revetment was constructed by using mechanically dewatered clay (MDC) lumps made from dredged material in the third area of the Shinmoji-Oki disposal pond (S-3) 9 years ago. Since this sample is an artificial material, its long-term stability has not been confirmed. In order to understand the evolution of the properties of the constructed revetment over time, mechanical tests, such as direct shear tests, have been conducted on block samples taken from two designated areas of the extra fill on revetment over the nine years since its construction. As a result, it was confirmed that the shear strength under certain overburden effective stress was sufficiently satisfied with the value assumed in the original design and the strength properties did not change much after 9 years, although the strength constants varied.

Katsuhide Nishizono, Yasuhiro Sega, Masaaki Katagiri, Yoichi Watabe

### Experimental and Numerical Evaluation of Clay Soils Stabilized with Electric Arc Furnace (EAF) Slag

In this paper, engineering characteristics and settlements of clay soils stabilized with EAF slag were evaluated by laboratory experiments and numerical analyses. The strength parameters obtained from laboratory tests constituted the input parameters of the numerical analyses that displayed the settlements of clay soil layers under shallow foundations. In the experimental part, clay soil was replaced with EAF slag at 30 and 50% ratios, and triaxial compression tests and one-dimensional consolidation tests were conducted at various initial confining stresses to obtain the strength parameters of the clay-EAF slag mixtures. The test results showed that partial replacement of EAF slag with clay soil provided significant improvements on the strength and compressibility parameters of the clay soils. In the numerical analyses, the settlements of clay layers under the shallow foundations were evaluated by replacing the mechanical properties of clay-EAF slag mixed soil instead of clay soil. The findings of the numerical analyses showed that the maximum excess pore pressure development in clay-EAF slag mixtures was 77% (70C-30EAF) and 90% (50C-50EAF) less than the clay soil, and the development area was shifted to the untreated part of the soil. The consolidation duration was two times shorter in 50C-50EAF specimens and the level of settlement decreased by 20% (70C-30EAF) and 36% (50C-50EAF) compared to the untreated soil.

Muhammed Mahmudi, Selim Altun, Tugba Eskisar

### Experimental Study on Engineering Properties of Soft Soil Stabilized by Overboulder Asbuton

Buton Island in Southeast Sulawesi, Indonesia, has a large amount of over 660 million metric tons of asphalt deposit in many forms. One of the types is overboulder which about 30% of the total deposit of asbuton. Overboulder occurred naturally when limestone reacts with bitumen in the topsoil layer of asbuton itself, making it a waste material which could be used as stabilizer material, due to its lime content with low bitumen content at about below 2%. The objective of this research was to analyze the effect of overboulder addition to soft soil as a pozzolanic agent and certain curing time to its unconfined compressive strength and CBR value. The soft soil was compacted according to ASTM D-698 standard method, as well as soft soil with overboulder addition. The UCT and CBR specimen was remolded based on its optimum moisture content and maximum dry density obtained from the compaction test. The unconfined compressive test was conducted according to ASTM D-2166 methods, and CBR test was conducted according to ASTM D-1883 methods. All specimen was treated with 0, 3, 7, 14, and 21 days of curing time in order to maximize its pozzolanic reaction between soil and overboulder asbuton. The overall result of the test shows that overboulder asbuton addition to soft soil increases its mechanical/engineering properties. Overboulder asbuton has potential as a local alternative to cement and/or lime in soil–cement and/or soil–lime stabilization due to its pozzolanic properties.

Noor Dhani, Tri Harianto, A. R. Djamaluddin, Ahmad Gasruddin

### Fundamental Study on the Effect of CO2 Curing on the Strength Development of Alkaline Construction Sludge

Construction sludge is known as waste material generated from construction industry. Since the construction sludge is usually very soft and at a high water content, it is often necessary to treat it with cement or lime to be recycled as construction materials. However, after the treatment, the increased pH sometimes cannot satisfy environmental regulation. By injecting high-pressure CO2 gas into the specimens, neutralization of alkaline construction sludge was accelerated. This research aims to study the effectiveness of using cement, CO2 gas, and paper sludge (PS) ash for not only lowering the pH level but also strengthening the alkaline construction sludge to be re-used in long-term durability. Alkaline simulated sludge having similar pH levels and state with the actual sludge were produced in the laboratory. The observed results showed that pH was decreased from more than 11.5 to around 8.6 after 7 h curing by the injection of CO2, whereas the addition of PS ash shortened the CO2 curing time. The strength of simulated samples was decreased during CO2 curing but then rapidly increased under air curing conditions. Strength of the samples with PS ash was seen significantly improved compared to that of samples without PS ash. After CO2 curing, under air curing conditions, the pH of treated samples tended to rebound to a certain level less than the original value, but then gradually decrease. It can be seen that the maximum value of pH rebound depends on the pH value obtained at the end of the CO2 curing.

Nguyen Duc Trung, Kimitoshi Hayano, Hiromoto Yamauchi

### Fundamental Study on the Mechanical Characteristics of Sand Treated by a PS Ash-Based Improving Material

This paper presents the potential of using paper sludge ash (PS ash) to improve the properties of sand for the usage as a backfill material. So far cement and lime have been used to increase the liquefaction strength of the backfilled sand around underground pipes and manholes. However, the cement- or lime-treated backfilled sand sometimes solidifies too much resulting in the problem of re-excavation ability. In this study, Toyoura sand improved by adding PS ash was investigated to evaluate the ability to be re-excavated by analyzing the unconfined compression strength. Moreover, a comparison of the results with the cement improvement case was conducted. Experimental results show that the qu of treated sand increases with the increase of PS ash addition ratio. However, the curing effect on strength depends on the addition ratio. It is revealed that the PS ash addition ratio 2.5–5.0% is recommended for PS ash-treated specimen since their unconfined compressive strength is moderate over time.

Maliki Otieboame Djandjieme, Kimitoshi Hayano, Yoshitoshi Mochizuki, Hiromoto Yamauchi

### Performance Assessment of Recycled Tire Materials in Marine Landfill Application

In the marine landfill sites, the alluvial clay layer is mainly used as the impermeable layer at the bottom of the site. This paper provides initial findings regarding the utilization of tire-derived geomaterials (TDGM) in the form of a horizontal layer placed between waste and alluvium clay layers in marine landfill sites. The purpose of installing the reinforcement layer is to protect the alluvium clay layer (Impermeable layer) from waste input. On the other hand, the reinforcement layer is also placed underneath the waste to ensure the collection and drainage of leachate during the degradation and the consolidation of waste. The effectiveness of such configuration is investigated numerically with the PLAXIS 2D software. The Sekiguchi-Ohta model (Viscid model) and hardening soil model are used as the material model, so that the settlement behavior was captured. The purpose of this research is to evaluate the effectiveness of horizontal reinforcing inclusion made from TDGM in mitigating settlement and damage of the alluvium clay layer.

Chunrui Hao, Hemanta Hazarika, Yusaku Isobe

### Performance of Rubble Brick Drains in Earthquake-Induced Liquefaction Mitigation Under Existing Buildings

Countermeasure techniques against earthquake-induced liquefaction aim to mitigate damage on infrastructures. Vertical drains performance has been evaluated during the last decades showing effectiveness in the reduction of structural damage. The performance of alternative drain arrangements considering the influence of existing buildings have been recently analyzed showing positive results on foundations settlement reduction. Although geotechnical mitigation measures main objective is to reduce detrimental effects in buildings, it is also important to incorporate economic and environmentally sustainable solutions. In this paper, the use of recycled coarse material inside drains such as high permeable rubble brick obtained from post-earthquake debris or buildings demolition is examined. Dynamic centrifuge test series was carried out to evaluate the performance of rubble brick vertical drains placed around existing foundations with different loads. The study shows the influence of the foundation load variation on the excess pore pressure generation due to earthquakes, the following post-seismic dissipation, and the foundation response.

Samy Garcia-Torres, Gopal Santana Phani Madabhushi

### Performance of Sand–Rubber Mixture Infill Trench for Ground Vibration Screening

Ground vibrations arising from construction and industrial activities and road/rail traffic can induce settlement issues, cracks, and severe damage to adjacent and remote structures. One of the well-established methods to eliminate such unwanted ground-borne vibrations is to incorporate trench barriers between the source of vibration and the structure to be protected. Recently, the use of shredded rubber from recycled tires has gained prominence in various geotechnical applications. The high energy absorption capacity of rubber is well established in the past, making it an ideal material in vibration mitigation studies. In the present study, 2D finite element analysis was carried out to investigate the use of sand–rubber tire mixture (SRM) infill trench barriers for the screening of ground-borne vibration due to vertical ground vibrations. In the present study, the typical soil profile from the Indo-Gangetic plain region is considered. 1 m width open and SRM infill trenches with a depth of 1–3 m are considered. The rubber content in the SRM fill trenches was chosen as 30% and 50%. The hyper elastic material model was adopted for the modeling of the SRM infill trench, while the soil medium was modeled using the hypoelastic constitutive model. The ground excitation was created by applying sinusoidal vertical motion with 2 m/s amplitude and a frequency of 50 Hz at the ground surface away from the trench. During the excitation, the vibration levels were computed at different locations in front of and away from the trenches. It was found that SRM infill trench with 50% rubber content performs similar to the open trenches to reduce the vertical vibration amplitude.

J. S. Dhanya, A. Boominathan, Subhadeep Banerjee

### Potential Application of Bauxite and Iron Mining Residues in Civil Construction in Brazil

Alumina is generated from the processing of an ore known as bauxite; the process generates a highly alkaline red-colored waste containing iron, titanium, and silica that can change any material’s properties that comes into contact with the waste. According to Abal (Aluminio Associação Brasileira de Aluminio: Perfil da indústria Brasileira do. São Paulo 2019 [1]), Brazil is the third-largest producer of alumina in the world and the fourth-largest bauxite producer. On the other hand, iron is one of the most abundant natural elements being obtained from minerals such as hematite, magnetite, limonite, and siderite. Brazil is the second-largest producer of iron ore globally, mainly in the region known as the Quadrilatero Ferrífero QF in the Minas Gerais State. The storage and disposal of waste from iron and aluminum production has become a major environmental problem. South America is a region rich in mineral resources, so the number of tailings dams is very high and, in most cases, built without respecting international standards and good engineering practice. Exploring mineral resources and destroying the native forest, contaminating water resources, and throwing gases and particulate matter into the atmosphere also consume much energy and contribute to global warming. The main methods of disposal of mineral products in Brazil are the cheapest wet path and have a much higher potential for environmental impact than the dry path. In recent years in Brazil, there have been significant tragedies involving tailings dams of iron, such as the failure of the Fundão dam on November 5, 2015, and the Brumadinho dam’s failure on January 25, 2019. Both cases caused the deaths of approximately 270 people and 25 missings. Thus, better mechanisms should be evaluated for the disposal of mining tailings such as dry processing and to reduce the use of dams in Brazil and South America. This work aimed to investigate the potential uses of alumina and iron tailings in civil construction. The waste has reasonable characteristics to be used as embankment fill material in infrastructure works, foundation material of some engineering works, ground improvement, or calcined additives in cement manufacturing and flexible pavements.

Julian Buritica Garcia, Virginie Queiroz Rezende Pinto, Juan Félix Rodríguez Rebolledo

### Reuse of Waste Tires to Develop Eco-rubber Seismic-Isolation Foundation Systems: Preliminary Results

This paper presents preliminary experimental investigations carried out to evaluate the feasibility of using gravel–rubber mixtures as low-cost geotechnical seismic-isolation foundation systems for low-rise buildings in New Zealand. One-dimensional compression and direct shear tests are performed to evaluate the compressibility and strength properties of three types of rigid-soft granular mixtures prepared using a combination of uniformly-graded rounded and angular gravels as well as large and small recycled rubber particles. The mixtures are prepared at volumetric rubber contents (VRC) of 10%, 25%, and 40%. The concept of skeleton material is adopted to establish whenever the gravel or rubber matrix would govern the overall mechanical behavior of the mixtures. It is shown that the compressibility of the mixtures highly depends of the skeleton material. Mixtures with VRC < 10% (gravel skeleton) perform better than those with VRC ≥ 25% (rubber skeleton), i.e., smaller vertical strains are developed under the same applied vertical stress level. Moreover, within the range of VRC tested, the mixtures made of large rubber particles are less compressible than those consisting of small rubber particles. On the other hand, under the testing conditions investigated, all mixtures exhibited high strength (i.e., friction angle > 35°) irrespective of the VRC and rubber particle size.

Gabriele Chiaro, Ali Tasalloti, Alessandro Palermo, Gabriele Granello, Laura Banasiak

### Shear Characteristics of Geomaterials Mixed with Fibrous Wood Chip and Converter Steelmaking Slag

Under-sieve residue is a sediment containing large amounts of wood chips generated by natural disaster. The mechanical properties of this residue have not been well understood, and thus, it has usually been landfilled. The development of a method for effective utilization of under-sieve residue is believed to facilitate quick recovery and reconstruction during disasters. Accordingly, this study aimed to devise an effective approach to convert under-sieve residue into a geological material. Consolidated-drained triaxial compression (CD) tests were performed using mixtures of coconut fiber, which closely resembles under-sieve residue, with steelmaking slag and blast furnace slag fine powder to understand the effect of the mixing ratio of coconut fiber and curing periods. The results indicated that the maximum shear strength of the slag mixed with coconut fiber at 5% (coco5) by volume was higher than that of a “slag only” specimen regardless of curing periods. The maximum shear strength of the slag mixed with coconut fiber at 10% (coco10) or 33% (coco33) by volume was higher than that of “slag only” without curing. However, the maximum shear strength of coco10 or coco33 did not increase with curing.

Tomotaka Yoshikawa, Yoshiaki Kikuchi, Shohei Noda, Akihiro Oshino

### Shear Strength Enhancement of Soil Mixed with Palm Oil Clinker

Amizatulhani Abdullah, Cut Ainul Mardziah Amir, Mohd Yuhyi Mohd Tadza

### Study on Bio-cementation of Ex-coal Mining Soil as a Road Construction Material

Hundreds of thousand hectares of ex-coal mining land are left without good management and use. This abandoned mine soil can be reused. This soil is composed of coal, sand and clay. Microstructural analysis shows that this material contains the chemical elements of quartz, titanium dioxide and clay minerals. This soil has been analyzed to determine its engineering properties and potentials for use in civil engineering construction. In this study, this soil was treated with bio-cementation to improve geomechanical properties by adding 3% and 6% Bacillus subtilis bacteria with bacterial culture for 6 days. Direct shear testing is done to see the increase in CBR and shear strength. The results showed that the CBR and shear strength of the soil increased with the addition of 6% bacteria and a curing time of 28 days then 3% bacteria in the same curing time.

A. M. Indriani, Tri Harianto, A. R. Djamaluddin, A. Arsyad

### Utilization of Coal Gangue for Earthworks: Sustainability Perspective

In recent years, there is a growing trend to utilize industrial residues/wastes with the aim of conserving natural resources. However, the environmental impacts in the form of carbon emission associated with their utilization ought to be predetermined prior to their promotion as a sustainable alternative to natural materials. This study aims to quantify the environmental impacts associated with the application of coal gangue (CG) in earthworks by performing carbon footprint analysis (CFA) and cost analysis (CA). An ongoing project of reinforced earthwork construction undertaken by the Government of Telangana, India, has been considered for the CFA and CA of coal gangue utilization. Prior to the CFA and CA, the feasibility of using CG for reinforced earth wall was ascertained by studying its geotechnical characteristics. Additionally, CFA was also performed to quantify the carbon emission associated with the disposal activity of unused CG. Results revealed that CG exhibited favorable geotechnical properties to enable its applications in earthworks. The CFA results indicate that the procurement and haulage of raw materials accounted for maximum carbon emissions and utilization of CG can eliminate 361 CO2eq (kg) associated with its disposal. Further, the CA revealed that CG utilization in earthworks results in Re 3333/m3 reduction in cost of construction. Furthermore, the results of the study revealed that the utilization of CG can lead to a significant decrease in the carbon footprints by eliminating the carbon emission associated with disposal of CG, thus creating a positive impact on the environment.

Mohammed Ashfaq, M. Heera Lal, Arif Ali Baig Moghal

### A Consideration on Numerical Model for the Relationship Between Evaporation Efficiency and Volumetric Water Content

It is important to obtain the amount of evaporation from the slope surface to analyze slope stability after rainfall. The bulk method is one of the evaporation estimation methods. Using this method, the amount of evaporated water from bare ground surfaces can be estimated from the general meteorological data. The evaporation efficiency, β, is an important parameter of the bulk method and is influenced by the volumetric water content in unsaturated soil. The molecular diffusion distance, F(Wv), is also an important parameter to calculate β. F(Wv) is influenced by the type of surface soil, the void ratio, and the volumetric water content, etc. The functional form of F(Wv) was obtained from experiments, and the experimental relationships between the volumetric water content and F(Wv) for loam and sand were explained by Kondo et al. In this paper, a numerical model for the molecular diffusion distance, F(Wv), derived from soil parameters such as grain size and void ratio is proposed, and β obtained from our proposed numerical model is compared with the results of laboratory tests by Sako et al. As a result, the applicable scope of the numerical model and the necessity of improvement of the numerical model are discussed.

Yuta Jikuya, Kazunari Sako, Shinichi Ito

### A Finite Difference Scheme for the Richards Equation Under Variable-Flux Boundary

The Richards equation is a degenerate nonlinear partial differential equation which serves as a model for describing a flow of water through saturated/unsaturated porous medium under the action of gravity. This paper develops a numerical method, with a mathematical support, for the one-dimensional Richards equation. Implicit schemes based on a backward Euler format have been widely used, but have a difficulty in insuring the stability, because of the strong nonlinearity and degeneracy. A linearized semi-implicit finite difference scheme that is faster than the backward Euler implicit schemes is established, the stability of this scheme is proved by adding a small perturbation to the coefficient function, and an error estimate is made. It is found that there is a linear relationship between the discretization error in a certain norm and the perturbation strength.

Yasuhide Fukumoto, Fengnan Liu, Xiaopeng Zhao

### Centrifuge Modelling Influence of Various Integration Schemes of Retaining Walls on Seismic Behaviour Using Tilting Table Test

More than 4000 retaining walls were damaged during the Kumamoto earthquake in 2016. Among them, approximately 60% were masonry retaining walls. There are mainly two types of masonry retaining walls in Japan. One is an air masonry retaining wall, which is unfilled with mortar, and the other is an integrated stone masonry retaining wall, which is filled with mortar. In addition, there is another type of retaining wall which is filled with mortar only on its surface so that the entire masonry retaining walls are not integrated and many of this type of retaining walls were damaged during the Kumamoto earthquake. The purpose of this study is examining how the integration of retaining walls affects their earthquake resistance. In this report, in order to confirm it from the deformation behaviour during an earthquake, we modelled the different types of retaining walls and conducted centrifuge tilting experiments. A series of centrifuge model tests were carried out under 20G, where a model retaining wall ground was tilted using a tilting table, a horizontal seismic force during an earthquake was reproduced, and the deformation behaviours of different types of model retaining walls during an earthquake were confirmed. Three types of model retaining walls made of plaster were reproduced including an air masonry retaining wall which is not integrated, a simple reinforced air masonry retaining wall which is integrated only on its surface, and a gravity retaining wall.

Kazuya Sano, Kazuya Itoh, Tsuyoshi Tanaka, Naoaki Suemasa, Takeharu Konami

### Effect of Bearing Pressure on Liquefaction-Induced Settlement in Layered Soils

Earthquake-induced liquefaction causes extensive damage to infrastructure. Soil liquefaction-induced effects can account for a significant proportion of damage such as the settlement of existing buildings on liquefiable soils. The influence of structures on the behavior of liquefiable soil is complex. In this paper, the effect of bearing pressure on liquefaction-induced settlement in layered soils was studied. Two 1 g shaking table tests, with different model buildings and bearing pressures, were conducted to establish the ultimate settlement of different structures in liquefiable layered soils. The results showed that as expected the settlement of the heavier building was larger than that of the lighter one. However, the settlement ratio of two buildings was smaller than the bearing pressure ratio. This study will be used as a benchmark for further testing on improving performance through the use of soil reinforcement methods.

Yutao Hu, Hemanta Hazarika, Siavash Manafi Khajeh Pasha, Stuart Kenneth Haigh, Gopal Santana Phani Madabhushi

### Evaluation of Ground Anchor Residual Tension by Vibration Method

A new method of non-destructive evaluation for residual tensile load of ground anchor has been developed. If the tendon tension part of a ground anchor is approximated by a “string” or “beam”, the frequency of its free vibration is determined by line density and tendon length of the PC steel and the operating tension. Although the free vibration of tendon tension part cannot be directly excited because it is in the ground, it is confirmed by a physical model experiment that the free vibration can be excited by applying a power at the extra length of anchor head. A series of field experiments was conducted by using a small vibrator and an accelerometer. A swept-frequency vibration was applied to the extra length of anchor head, and the vibration waveform was measured at the same position. The observed waveform was analyzed by running spectrum analysis in order to find a resonance frequency which is used to calculate the residual tension load.

Kazuki Nawa, Atsushi Yashima, Yoshinobu Murata, Keizo Kariya, Hideki Saito, Kunio Aoike, Yoshinori Sone, Mitsuru Yamazaki

### Jet Grouted Columns with Horizontal Slab as Ground Improvement Towards Liquefaction Mitigation

A new countermeasure method of jet grout columns with horizontal slab in liquefaction mitigation is introduced in this study. In order to investigate the effectiveness of the proposed mitigation method, numerical studies on unimproved and improved ground were separately performed. Additionally, the validations of the numerical model geometry with boundary conditions and parameters used in UBC3D liquefaction model were conducted prior to the analyses to confirm the reliability of the numerical results. The effectiveness of the soil improvement method was assessed by comparing the changes in excess pore water pressure ratio, acceleration as well as distribution of shear stress and shear strain in the liquefiable soil before and after ground improvement. The results show that the new liquefaction mitigation method offers optimistic effect on control of shear deformation and excess pore water pressure.

Myat Myat Phyo Phyo, Hemanta Hazarika, Hiroaki Kaneko, Tadashi Akagawa

### Mechanical Behaviors of Assembled Multi-step Cantilever-Retaining Walls for High Embankments by Numerical Simulation Method

Assembled multi-step cantilever-retaining walls are a new type of light-retaining structure with low carbon, which can be suitable for high fill earthworks and quickly installed in situ. In order to fully support practical design of the novel-retaining structure, mechanical behaviors of the structure under strip surcharge on the top surface of the backfill in a high embankment example are determined using numerical simulation method via Flac3D program. Analysis results show that the profile of the lateral earth pressure on the vertically assembled walls exhibits multi-segment polyline mode. Apart from the highest step wall member, there is obvious reduction effect of the earth pressure at the top of each wall member. The increases of width of heel plate of wall member, internal friction angle and unit weight of the backfill are helpful to improve the overall stability of the wall-slope system and reducing lateral displacement of the whole wall. Moreover, considering easy construction of the structure in practice, relatively more steps under allowable conditions are also commonly recommended for the retaining structure.

Zhaoying Li, Shiguo Xiao

### Microscopic Analysis of the Influence of Pore Size Distribution on SWCC Using Extended DDA

Soil–water characteristic curve (SWCC) is one of the most important properties of unsaturated soil, and pore size distribution (PSD) curve is commonly used to predict SWCC. In this study, an extended discontinuous deformation analysis (DDA) method is used to reveal the influence of PSD on SWCC from the micromechanism. First, the performance of the extended DDA method is validated by the experimental SWCC. And DDA microsimulation result is in good agreement with the experimental result. Then, the relationship between PSD curve and SWCC is analyzed based on the DDA simulation results. The microsimulation results show that PSD influences SWCC by changing the capillary radius in soil. Air-entry value decreases with the percentage of large pore increase. However, the effect of PSD on SWCC tends to diminish at the residual zone because the micropores do not show much difference between two models. This study extends DDA in unsaturated soil analysis and provides support for PSD-based SWCC prediction from the micromechanism.

Longxiao Guo, Guangqi Chen

### Physical Model Tests for Newly Developed Breakwater Foundation Subjected to Earthquake and Tsunami

Many breakwaters damaged due to earthquake and tsunami in the past. For example, several breakwaters collapsed by the 2011 off the Pacific Coast of Tohoku Earthquake and subsequent tsunami. It was found that these breakwaters damaged mainly due to the failure of their foundations. Therefore, countermeasures are urgently needed to be developed for breakwater foundation in order to make the breakwater safe against earthquake and tsunami. Recently, new countermeasures were developed by the authors for breakwater foundation in order to make it resilient against an earthquake and tsunami. This paper deals with evaluation of effectiveness of the developed foundation model by conducting shaking table tests and tsunami overflow tests. As reinforcing countermeasures, steel sheet piles and gabions are provided in the breakwater foundation. To see the performance of the developed model, comparisons are made between the developed foundation model and conventional foundation. Through the tests, it was found that the reinforced foundation performed well in reducing damage of the breakwater caused by the earthquake and tsunami.

Babloo Chaudhary, Hemanta Hazarika, Akira Murakami, Kazunori Fujisawa

### Simulation of Crack Initiation and Propagation Using the Improved DDA

This paper analyses the rock fracture problem of Brazil disc split tests by using an improved DDA method. By incorporating a new rock fracture law and the discretization approach, the improved DDA can be used to simulate crack propagation during the rock fracture process in a two-dimensional plane stress state, such as the crack propagation in Brazil disc split tests. A numerical example of simulating the Brazil disc split tests for verification has been computed using the proposed DDA method. The simulated result agrees well with those obtained from the experiment, which proves the effectiveness and accuracy of the proposed DDA method. Meanwhile, the Brazil disc split test under different loading rates is performed systematically to investigate the external influences on rock fracturing. The result shows that the improved DDA can be well used for simulating the two-dimensional dynamic rock fracture problems in engineering.

Mingyao Xia, Guangqi Chen

### Stability Assessment on Expressway Embankment by Automatic Survey System

Collapses of expressway embankments due to large earthquakes and heavy rainfalls have been reported. Those collapses often closed important transportation routes and resulted in serious damages in communities. Inappropriate groundwater treatment and slaking/weathering of embankment materials contribute to these collapses. In order to diagnose road embankment soundness, we have to visualize the inside the embankment. The automatic technology for surveys and evaluations of embankments by using surface wave logging and electric resistivity logging has been proposed. We performed initial diagnostics before the opening of the expressways to evaluate embankment materials and stability of the embankment, especially in the vicinity of the stiff structures, such as box culverts and around the boundary between embankment and cut section. The desired target inspection speed, 500 m per h (mean speed), was achieved. The stiffness of embankment was continuously obtained for many sections with different fill materials as the initial reference data for future inspection. Based on the comparison between initial reference data and those obtained in the future, it is possible to select the optimal countermeasures to ensure the continuous stability of the road embankment.

Kosuke Nakashima, Atsushi Yashima, Yoshinobu Murata, Keizo Kariya

### Stability of Reinforced Soil Quay Wall Subjected to Combined Action of Earthquake and Tsunami

Reinforced soil quay walls are used as shore protection systems. Generally, horizontal layers of geogrids are provided as reinforcement in the backfill soil of the quay wall. These structures are internally stabilized by mobilized tensile strength of reinforcements. A quay wall can be subjected to tsunami load and earthquake load simultaneously. This condition occurs when an earthquake aftershock reaches the quay wall structure at the same time of a tsunami impact. Therefore, a combined analysis of quay walls subjected to earthquake and tsunami at the same time is necessary. In this study, horizontal slice method is used to evaluate the stability of the reinforced soil quay wall subjected to earthquake and tsunami. The failure surface is generated by optimizing the angle of failure plane of each slice, so that the mobilized tensile force on the reinforcement is maximum. Thus, the generated failure surface could justify the actual failure surface. It was observed that normalized force acting on the reinforcement is considerably increased under the combined effect of earthquake and tsunami. Stability of the wall is evaluated by varying several parameters, such as acceleration coefficient of earthquake motion, internal friction angle of soil, inclination and height of the quay wall, height of seawater level and height of tsunami waves, to find out the effect of these parameters on normalized reinforcement strength.

Manu K. Sajan, Babloo Chaudhary

### The Influence of Coupled Horizontal and Vertical Components of Strong Ground Motions on the Ground Response Analysis: Experimental and Numerical Approaches

The large vertical ground motion during the 2008 Iwate-Miyagi Nairiku earthquake showed the importance of not only the horizontal ground motion but also the vertical motion in strong ground motion prediction and response analysis. In this study, considerations about the interaction behavior between the horizontal motion and the vertical motion during a strong earthquake were carried out by one-dimensional elasto-plastic earthquake analyses and cyclic shear box tests. It could be concluded from the results that the change of confining pressure caused by vertical motion affects the horizontal behavior, and strong horizontal motion produced vertical motion in the soil layer above the groundwater level.

Tsubasa Maeda, Hazarika Hemanta, Yoshinori Kato

### Verification of Seismic Deformation of Road Embankment Laying on the Coast Using Numerical Analysis

Following the 2011 Off-Pacific Coast of Tohoku Earthquake, embankments have again attracted much attention as a tsunami restraining measure. Because of alluvial deposit widely distributed along the coast, liquefaction of the ground often obstructed the traffic function. In this paper, the characteristics of the sedimentary layer of the coast are sorted out from the viewpoints of landform division and grain size analysis results for a local coast in Kochi Prefecture. Furthermore, effective stress analysis is conducted at various liquefaction ground condition represented in the coastal area. Using the results of this analysis, the relationship between the characteristics of the ground and embankment deformation is established. Finally, a simple evaluation method for road embankment settlement is suggested using the results of the effective stress dynamic analysis which is often conducted for the design of road embankments with a large-scale earthquake in mind.

Kentaro Kuribayashi, Tadashi Hara, Shuichi Kuroda

### Behavior of Unsaturated Silty Soil Due to Change in Water Content and Suction

To reduce and mitigate rainfall-induced problems, there is a need to improve understanding of the failure mechanism of unsaturated soil due to changes in water content in the soil body. Natural slopes, man-made slopes and embankments are generally made of unsaturated soils. In this regard, the objective of this study is to investigate the behavior of unsaturated silty soil due to change in water content and suction. The change in the water content of the sample represents the effect of rainfall. Moreover, this study aimed at understanding the effect of the degree of compaction on the strength and deformation characteristics of unsaturated silty soil. In the experiments, two series of laboratory element tests on double-cell triaxial machine carried out on DL clay (silty soil) in which water content varied from dry to wet of optimum moisture content, and the degree of compaction varied to study the effect at diverse overburden pressures. The test series is conducted in constant water content condition, and the measurements are closely monitored throughout the test course (initial suction to shear) to observe the changes in effective stress. The observed changes in the parameters are also presented in three dimensions to show the behavior of soil under the influence of more than two parameters. From this research, it is examined that with the increase in degree of compaction, volume change behavior transformed from compressive to dilative. Moreover, the strength of the silty soil increased with the increase in suction, i.e., due to decrease in water content, and vice versa.

Ibrar Ahmed, Jiro Kuwano, Adnan Anwar Malik, Dipak Raj Shrestha

### Cyclic Strength and Deformation Characteristics of Sand Containing Fines with Plasticity

The strength and deformation characteristics of sandy soil with fines have not been sufficiently clarified, when the fine content ratio is high, but the plastic index is low, or the plastic index is high, but the void ratio is also high. The “ALID” program has been used to simulate the deformation of river levees during earthquakes. In some cases, the results of deformation obtained by analysis and determined in situ in the ground during earthquakes do not coincide entirely, because the properties of such soil with fines are unclear. In the present study, several series of cyclic loading tests and monotonic loading tests after cyclic loading were performed, in order to investigate the strength and deformation characteristics of sandy soil with several plasticity indexes, fine content ratios and void ratios. Consequently, the effects of the properties on the strength and deformation characteristics are clarified using the liquefaction strength and the shear modulus after liquefaction.

Hideo Nagase, Akihiko Hirooka, Keigo Fukumoto, Keiichiro Miyaji, Naoya Kawano

### Effect of Mineral Additives on the Strength Characteristics of a Laterite Soil

The road access opening, frequently through several soil conditions, do not comply with the construction requirements. Thus, it needed materials that could protect the low bearing capacity of subgrade and strengthen the pavement layers from a load of the vehicle’s wheel. This study aimed is to analyze the performance of the subbase layer, which consists of zeolite-stabilized laterite soil using water glass as an activator. The mechanical characteristics of the unconfined compressive strength (UCS) and California Bearing Ratio (CBR) value were investigated in this study. The soil sample was prepared with a zeolite percentage of 4, 8, 12, 16, 20%, and combining with 2% of water glass. Prior to the test, the soil samples set to the maximum dry density (MDD) and optimum moisture content (OMC) condition. The result of the mechanical characteristics of the stabilized soil showed that the higher UCS and CBR value was observed compared to untreated soil. The mechanism of the improvement of stabilized soil is also discussed.

Tri Harianto, Widya Dwi Utami

### Effect of Spatial–Temporal Discretization Order on the Selection of Lattice Boltzmann Forcing Strategy in Convective Flow Simulation Within Internal Geometrical Arrangement of Concrete Structure

This article reports on comprehensive assessment regarding conjoined effect of discretization order of the continuous Boltzmann equation and discrete forcing scenario in the feasibility of lattice Boltzmann method (LBM) as an interlinked hydrothermodynamics solver. A two-dimensional natural convection phenomena within the geometrical pore arrangement of the concrete structure was modeled as a synergetic embodiment of the discrete lattice fluid and thermal counterparts. Four different combination strategies of LBM implementation were carefully examined, elucidating theoretical and numerical segments, in order to expose any plausible discrepancy in the retrieved steady-state solutions. It was found that the numerical outcomes from distinct LBM strategies return equivalent results upon few selected key physical properties, despite incisive difference that emerges in the theoretical aspect. Excellent agreement with classical computational techniques was observed for all considered treatment options, underlining validity of our strategies. This study represents a further step toward clarification of the convoluted issue regarding proper selection of discretization order and forcing scheme in LBM simulation.

Aditya Dewanto Hartono, Kyuro Sasaki, Ronald Nguele

### Effects of Water Absorption and Retention Performance of Paper Sludge Ash in Combination with Cement to Stabilize Dredged Soil

Due to its ability to absorb and retain water, paper sludge ash, a cinder generated from the incineration process of paper sludge, is high potential in used as complement to cement in stabilizing dredged clay soil. In this study, an attempt is made to bring out the effectiveness of combining paper sludge ash (PS ash) and cement in stabilizing dredged clay through a series of unconfined compression tests. Based on the investigated water absorption and retention performance of PS ash, a new parameter, unabsorbed water/cement ratio, W*/C, which is the ratio by weight of the clay–water content that was unabsorbed and unretained by PS ash to cement content, was used to assess the strength development of PS ash–cement-treated clay. It is revealed that the strength of the stabilized clay is governed by the parameter W*/C. The combination of cement and PS ash gives a treatment effect comparable to that of cement and even better for high water content clay. Experimental results show that it is high potential for PS ash–cement-treated clay to be used in soft soil stabilization.

Phan Nguyen Binh, Kimitoshi Hayano, Mochizuki Yoshitoshi, Hiromoto Yamauchi

### Fundamental Study of Adsorption Thin Layers for Safe Storage of Heavy Metal Contaminated Soil

Osamu Otsuka, Ryo Nishizato, Minoru Okuno, Naoto Watanabe, Tsutomu Matsuo, Tomomichi Obuchi, Takashi Mizobuchi, Yoichi Kitamura, Eriko Kikawa, Ken Sato, Hidekazu Shimohara

### Influence of Sand on the Behavior of Buffer Material Used for the Nuclear Waste Disposal

Clay–sand mixtures are being planned for use as buffer materials for high-level nuclear waste disposal. These mixtures are attracting greater attention as buffer materials because they offer properties of low volumetric shrinkage and high swelling. The influence of sand on the behavior of clay–sand mixtures was investigated by many researchers through a series of laboratory experiments. The study illustrates the role of coarser fraction in controlling swelling and shrinkage of clay–sand mixtures. In the present study, experiments were conducted using oedometer tests to investigate swelling and shrinkage properties at different sand contents by experimentation. The clay–sand mixtures were prepared with sand contents of 0%, 10%, 30%, and 50% by weight of clayey soil. The study showed a decrease in swelling potential and volumetric shrinkage with increase in the amount of sand. An increase in dry unit weight and a decrease in respective moisture content by an increase in the amount of sand were observed in the compaction tests. In addition, attempts were also made to find the influence of varying proportions of coarse sand and fine sand mixtures on swelling and shrinkage properties of these mixtures.

### Swell-Compressibility Behavior of Geopolymer Blended Expansive Clays

This paper presents the influence of GGBS-based geopolymer on swell-compressibility characteristics of oven-dry, expansive clay passing 4.75 mm sieve. One-dimensional swell-consolidation tests were conducted on the expansive clay passing through 4.75 mm sieve to which GGBS was added at 0, 5, 10, 15, and 20% by dry weight of the clay. Rate of heave, swell potential, swelling pressure, and linear shrinkage were evaluated. Rate of heave and swell potential decreased significantly with increase in GGBS content. The paper also explores the microstructure behavior and surface texture of the GGBS-based geopolymer–clay blends using the scanning electron microscopy (SEM). The SEM results revealed that the higher Si/Al compounds increase the dense phase of geopolymer products. Moreover, geopolymer synthesis can contribute to the bulk utilization of industrial by-products.

T. V. Nagaraju, B. M. Sunil, Babloo Chaudhary

### Swelling Behavior and Permeability of Polymerized Bentonite with Due Monomers

To improve the anti-cationic solution capability of geosynthetic clay liners (GCLs), new polymerized bentonites (PBs) were produced for potential use as cores of GCLs. PBs were produced using free radical polymerization method with due monomers, acrylic acid (M1) and acrylamide (M2), and potassium persulfate as initiator (I). The natural bentonite (UB) used was a sodium type one. The adopted pH was 6, I/(M1 + M2) ratio of 0.005, and (M1 + M2)/UB ratio of 0.05 (0.05 PB) and 0.1 (0.1 PB). The results of the X-ray diffraction (XRD) indicate that PBs produced in this study can be classified as micro-composite. The swelling capacity of the PBs was investigated by free swelling index (FSI) tests. In deionized water, 0.1 M to 0.6 M NaCl and 0.03 to 0.06 M CaCl2 solutions, the values of FSI of PBs are higher than that of UB. For PBs, FSI increased with increase of polymer/bentonite ratio. In deionized water, FSI of 0.1 PB was more than 5 times that of the UB. The values of permeability of the PBs and UB with 0.6 M NaCl solution were deduced from oedometer test results. At the same void ratio, the permeability of 0.1 PB was more than one order lower than that of the UB. For the 0.1 PB, for void ratio up to 7.5, the value of k was less than 10–10 m/s. Therefore, 0.1 PB can be used as core material of GCLs to be used under higher concentration of Na+ environment.

Nie Jixiang, Chai Jinchun

### Suitability of Mechanically Biologically Treated Waste for Landfill Covers

Landfills are one of the major sources of atmospheric methane (CH4), which causes global warming. The microbial oxidation of methane in engineered covers is considered a potent option for the mitigation of methane emissions from landfills or sites containing wastes of low methane generation rates. Studies have shown that microbial oxidation of CH4 in landfill cover soil is enhanced in the presence of organic matter-rich substrates. Hence, in this study, the methane oxidation potential for a mechanically separated, biologically treated, and anaerobically digested waste (MBT waste) is being investigated. Column experiments were devised for the study; the results of which indicate that the oxidation potential of the material is far above the reported average values. This suggests that the material could be satisfactorily used as a cover material in landfills. The gas concentration profiles obtained from the experiments were validated with the numerical model which gave matching results. This suggests that the methodology adopted to model the methane oxidation in the numerical model is satisfactory and could be used for future investigations.

T. G. Parameswaran, N. Anusree, P. Sughosh, G. L. SivakumarBabu, T. K. K. Chamindu Deepagoda

### Synergy Between Poly Vinyl Alcohol and Bentonite in Drilling Fluid Formulation: An Experimental Study

The formulation of a drilling fluid is mostly defined by the type of formation to drill. Ensuring drilling mud's effectiveness before throughout a drilling process implies monitoring its physico–chemical properties, including cake filtration. Cake filtration of a drilling mud can be either good or poor (loss filtration or fluid drag effect) depending on the mud swelling efficiency. A drilling mud made of bentonite (or Barite) still needs the assistance of appropriate additives to carry it to its optimum performance. The present study aims at monitoring the cake filtration of a water-based drilling mud using polyvinyl alcohol (PVA), which is known and used for its swelling abilities. The mud samples were formulated by blending two different types of PVAs (standard & synthetic PVAs) with deionized water at various concentrations (0.0%–0.3%) and 7% of bentonite. pH and density of muds were measured before filtration tests. The cake filtration was evaluated by injecting 10 mL of mud samples at constant pressure into a stainless steel Millipore sigma filter holder 90 mm at a constant pressure of 1.2 MPa. Results show that the addition of PVA increases the mud's acidity with the concentration of polyvinyl alcohol. The observed higher reliable content of the samples with standard PVA was confirmed by their higher density values, leading to lower filtrate productions than the muds samples with synthetic PVA.

Danielle Poungui, Kyuro Sasaki, Yuichi Sugai, Ronald Nguele

### Bearing Capacity Determination of Jointed-Timber Piles in the Saga Lowland

The pile load tests were conducted in the soft clay with high compressibility and lower shear strength with depths until 10–30 m in the Saga lowland, Japan. Generally, single-timber piles (STP) were used as the pile foundation of the small-scale buildings in this area. However, differential settlements were experienced in these buildings. To overcome the problems, the tip of the timber piles was required to reach supporting stratum at greater depth. In order to reach the stratum, the timber piles were connected with several joints. Until then, there were methods to calculate the bearing capacity of STP. However, there was no detailed study to describe the bearing capacity and its mechanism of the jointed-timber piles (JTP). Based on the several pile load test results, the bearing capacity evaluation method has been proposed for the JTP in terms of bearing capacity coefficients α and β. It was confirmed that the second limit resistance forces were higher than the bearing capacity evaluated with the proposed method, including the reduction effect of joints, length/diameter ratio.

Sailesh Shrestha, Yuki Matsumoto, Shunsuke Moriyama, Norihiko Miura

### Experiment of a Hard Rock Excavator by Using an Edge Excavation

Blasting method is a conventional method for hard rock mass excavation. Recently, the use of blasting method is getting difficult due to environmental problems, such as noise pollution and ground vibration. Mechanical excavation method is an alternative for the blasting method; however, the present excavation method has two problems: the low efficiency due to the wear of cutting bits and the high cost to exchange cutting bits. Thus, through this research, we are trying to innovate the edge excavation method in order to solve the two problems. The purpose of this study was to develop a rock excavator attached to backhoe by using multistage edge excavation method. We carried out the experiments by using model excavator to find out its efficiency and force acting on the rock excavator. In this study, we conducted a basic experiment by using a displacement controlling method to determine the load required to control a model excavator. The specimen used was high-strength mortar specimen. In the experiment, a model excavator was attached to the experimental device, and the speed was set to be constant by displacement control. Excavation was performed by rotating the specimen. The vertical force Fz, torque T, excavation depth z, and soil volume m, the excavation time t were measured. As a result, the load required for the model excavator was verified and the capability of the experiment to be performed through load controlling was confirmed.

Yudai Ihara, Takahisa Shigematsu, Shinichi Kawamura, Yoshihiro Ohnishi, Sho Miyanaga, Muhamad Afif Bin Osman

### Full-Scale Testing of a Structure on Improved Soil Replaced with Rubber–Gravel Mixtures

We present the results of an extensive large-scale experimental campaign on the dynamic response of rubber–gravel mixtures as an innovative seismic isolation material. In the first series of experiments, the foundation soil immediately below the prototype structure of EUROPROTEAS was replaced only with gravel to serve as benchmark tests, while in the following tests two rubber–gravel mixtures with increasing rubber content per mixture weight were used. The experimental campaign included free- and forced-vibration tests. A large number of instruments of various types (accelerometers, seismometers, shape-acceleration arrays, and laser sensors) were installed on the structure, in the foundation soil and at the adjacent soil surface in order to obtain a well-instrumented 3D set of recordings to study the response of the structure and wave propagation in soil media. In this study, we seek to investigate the isolation capability of the rubber–gravel mixtures under dynamic loading. Our primary goal is to assess the effect of the rubber content of the improved foundation soil in the stiffness and the damping of the soil-structure system.

Athanasios Vratsikidis, Angelos Tsinaris, Anastasios Kapouniaris, Anastasios Anastasiadis, Dimitris Pitilakis, Kyriazis Pitilakis

### Interdependence and Rationality Between Sustainable Indicators and Criteria—A Fuzzy AHP Approach

The rapid urbanization is likely to impose tremendous pressure on the available natural resources due to their depletion, seriously affecting the Social, Environmental, Economic and Technological (SEET) indicators. The identification of criteria and indicators to achieve Sustainable Construction (SC) is a challenging task in terms of balancing and interrelating them. The present study while investigating the most significant criteria that contribute to SC, establishes inter-relationship between them and SEET indicators by utilizing the Fuzzy Analytical Hierarchy Process (AHP), a Hybrid Multi-Criteria Decision Making (MCDM) method. Based on Delphi Technique (DT) and Relative Importance Index (RII), eight criteria have been identified including Water Efficiency, Materials and Waste Management, Health and Well-being, Energy Efficiency, Sustainable Sites, Social Welfare, Transportation, and Management. The findings of the study reveal that the criteria Materials and waste management and Energy Efficiency have attained the highest relative weights of 13.96 and 12.63 respectively. Similarly, among SEET indicators, the Environmental and Technological indicators have secured 30.15 and 28.52 relative weights respectively. This well-established inter-relation between indicators and criteria will facilitate the decision-makers/stakeholder to understand the degree of performance between sustainable criteria and indicators for achieving sustainable buildings. In addition to this, a computerized building assessment tool which can facilitate the formulation of guidelines by policy-makers was also developed.

Suchith Reddy Arukala, Rathish Kumar Pancharathi

### Introduction of the Recycling and Reusing Method of Screw Steel Pile EAZET

EAZET pile is a type of screw steel pile which consists of a pile shaft and a helical plate attached to the bottom. It is commonly known as an environmentally friendly pile method. It generates no surplus soil nor muddy water during installation by screwing the pile into the ground with its helical plate at pile tip. On the other hand, by rotating reversely, it can be pulled out and retrieved, thus also be recycled and reused if necessary. This article presents the recycling and reusing procedure and criteria of screw steel pile EAZET based on experience. For safe and smooth retrieval, capable machine should be chosen carefully in advance. The capacity of the machine and the torque during retrieval should be constantly noticed, especially when the retrieval is conducted long time after installation. The reason is that the ground disturbed by the pile installation has recovered, where it requires larger torque for pulling out. Retrieved piles will be examined via visual check, dimension check, and bending test of the pile shaft. After that, they will be divided into reusable members and non-reusable members. Reusable members can be repaired for future reuse. On the other hand, non-reusable members are recycled as reproduction materials for components in recycling factory. Recyclable and reusable features of EAZET enable it to be further adopted by temporary structures besides its original market. It can contribute to the transformation from economical society to recycling society where the efficient usage and recycling are emphasized.

### Mechanical Behavior of Cement-Treated Soils with Nanosilica—A Green Binder

This study deals with the mechanical properties of cement-treated soils with the addition of nanosilica particles. Different industries discovered the beneficial uses of nanoparticles; however, the potential use of nanoparticles in geotechnical engineering is a subject that is still unclear and needs some investigation. Nanosilica particles could act as a green binder for geotechnical site works. Therefore, in this study, the effect of nanosilica material in cement-treated clay and cement-treated clayey sand specimens were examined. Index properties, compaction characteristics and unconfined compressive strength of nanosilica added cement-treated soils were assessed. Tests were carried out on specimens with 0%, 5%, and 10% cement by dry weight of soil with 0%, 0.3%, 0.5%, and 0.7% nanosilica content to evaluate the strength properties of the specimens. The curing periods were 7 and 28 days. The results of the preliminary tests showed that, the inclusion of nanosilica resulted in a limited increase in the optimum moisture content of the specimens and the maximum dry density of the specimens had a limited decrease at 0.7% nanosilica content. The performance achieved by the addition of nanosilica particles was very remarkable compared to the specimens that were prepared only with cement. Clayey sand specimens with 5% cement and 0.5% nanosilica had a similar compressive strength with specimens that had 10% cement in 28 days. Consequently, inclusion of nanosilica particles in soils is a promising development to reduce the cement amount in cement-treated soils.

Gizem Aksu, Tugba Eskisar

### Structural Stability Against Earthquake and Tsunami Using Environmentally Sustainable Materials

Tsunami activated by earthquake is known to be one of the most powerful natural disasters. For instance, in March 11, 2011, tsunami activated by earthquake led to several compound disasters in Japan. Many coastal protection structures such as seawalls and breakwaters were found to be damaged seriously. In order to protect coastal structures from such kind of devastating damage in the future, it is essential to take proper countermeasures. A tire retaining wall in Iwate prefecture located just about 150 m away from a completely collapsed sea wall was found to be neither scoured nor damaged by tsunami, which indicates that the flexible tire structure has a great potential to reduce the tsunami impact force as compared to heavy and rigid structures. Therefore, main object of this research was to demonstrate how effectively tire structure will function against the earthquake and tsunami to protect sea wall from scouring on the foundation and resulting damage. A new model for simulation of tsunami impact force has been developed in Geotechnical Engineering Laboratory of Kyushu University. In which absorption of tsunami impact force and the dispersion effect of the tire structure was examined. Field experiments were also performed with various types of plants cultivated inside the soil-filled tires to see how the greening effect could be maintained. Results showed a better performance of the sea wall when protected with tires placed behind the sea wall. Also, field test showed that the greening effect could be maintained by cultivating suitable plants inside the tires.

Kiran Hari Pradhan, Hemanta Hazarika, Yasuhide Fukumoto

### Tip Shape Effect on Screw Pile Installation and Ultimate Resistance

In the field of deep foundations, the screw pile is one of the new ways of construction that can support infrastructure against extreme weather events. Moreover, its eco-friendly installation mechanics that involve quick installation, minimum noise and vibration; no wastage of material and reusability makes it more efficient than conventional piling techniques such as concrete piles which involves noise, consumption of natural resources, and wastage of materials. However, the use of screw pile in the dense ground with large helix is still a concern as higher torque and pushing force is required, which sometimes exceeds the limits of machinery. In this regard, the present study focused on the effect of helix tip shape on the installation torque and force under dense ground conditions. In addition to this, the effect of tip shape on ultimate resistance also studied. To investigate these effects, model-scale pile load tests are conducted. Three kinds of pile tip shapes, i.e., flat, cone, and cutting-edge ends are considered in this study. Toyoura sand is used as a model ground. Ground disturbance due to pile installation also monitored at various distance from the edge of the pile. To check the effectiveness of the screw pile, its results compared with the results of the straight pile having the same shaft diameter under similar ground conditions. The test results indicated that the overall performance of the screw pile with cutting-edge is better than other tip shape piles, and also better than straight shaft pile in terms of installation force, torque, surrounding ground disturbance, and ultimate resistance.

Adnan Anwar Malik, Yahya Ndoye, Jiro Kuwano

### Application of Deep Mixing Method for Mitigation of Potential Seismic and Hurricane-Induced Hazards

This paper describes the application of Deep Mixing Method (DMM) for the mitigation of potential hazards induced by natural disasters such as hurricane-induced ground flooding and seismic ground shaking for two projects in the USA. The two projects completed in 2014 and 2016 are used as case examples to present the design, construction, and quality control of the DMM work for hazard mitigation. DMM was installed in the first project called P-17A primarily to reinforce soft soils within and below a levee to provide resistance against lateral loads that will be induced from high flood generated by hurricane. The second project called Perris Dam included the use of DMM to improve potentially liquefiable soils within the foundation of an earthen dam primarily to limit the deformation of the dam during a seismic event.

Rakshya Shrestha, Nozomu Kotake, David Yang

### Characteristics of Surficial Mass Movements on Cut Slopes of the Prime National Highway 1 (PNH-1) in Bhutan

This article presents characteristics of surficial mass movements after cutting a slope through the Prime National Highway 1 (hereinafter abbreviated as PNH-1) in Bhutan. The surficial mass movement, in the form of slope failures, affects the ability of traffic to move along the PNH-1. The geology in the area of the PNH-1 consists of metamorphic rocks. There are several types of surficial mass movement in slopes, for instance, rock/soil slide, debris flow, and rock falls. Slope failure has occurred due to the geological discontinuities, the boundary of strata, joints, and so on. From the observation of more than 100 slope failures along the PNH-1, we classified the surficial mass movements into three types: “Denudation,” “Erosional flow,” and “Slide.” Among these three types, “Denudation” and “Erosional flow” destabilize the surface layer of the slope after a while after cutting, while “Slide” tends to collapse on the slope within a short time after cutting. According to Varnes’ landslide classification, surficial mass movements such as “Denudation” and “Erosional flow” are categorized as “Flows,” and “Slide” are categorized as “Slides.”

Kiyoharu Hirota, Tomohiro Nishimura, Takeshi Kuwano, Tomoharu Iwasaki

### Estimation of Liquefaction Area Using the Screw Driving Sounding Data in Kumamoto

On April 2016, the Kumamoto earthquake occurred. The earthquake caused serious liquefaction damage in the long and narrow area of about 5 km north and south between the Shirakawa River and the Midori River that flow west through Kumamoto City. In This area is called “Ekijyoka no obi (Liquefaction belt),” and many houses have sunk or tilted. The screw driving sounding test has some advantages including simpler test system and better cost efficiency for penetration in comparison with standard penetration test (SPT) and cone penetration test (CPT). For these reasons, the screw driving sounding test is often used in residential land surveys in Japan, and there is a lot of existing data in this area. In this paper, the spatial information on the Holocene geological situation of this neighborhood was generated made in this area spatial information using the screw driving sounding test data, and the phase change of the liquefied area, and the non-liquefied area was compared. As a conclusion, the spatial extent of the liquefied soil layer was estimated.

Kohei Tsuji, Naoaki Suemasa, Tsuyoshi Tanaka

### Deterministic Seismic Hazard Analysis of Ankleshwar City, Gujarat

Earthquake disaster study as well as mitigation is important for the safe and economic design of structures. Ankleshwar is the major industrial hub of India, situated in Bharuch district, located at south-west coast of Gujarat and lies in seismic zone III as per Indian seismic zonation. In present study, the seismic risk analysis of Ankleshwar city is carried out considering the past earthquake records. Earthquake catalogue consisting of all earthquake events from 1819 to 2019 is prepared within 400 km radius of the Bharuch district. After identifying the seismic sources and declustering of earthquake catalogue, the shortest distances from each seismic source responsible for the tectonic activity have been calculated. For the Ankleshwar city, the peak ground acceleration values at rock level have been determined using predictive relationships. The analysis reported that the PGA values are ranging from 0.18 to 0.38 g with respect to maximum credible earthquake of magnitude (Mw) 5.8 generated from Son Narmada Fault. The basic design parameters arrived from the PGA model can be used for the seismic design of structures in the Ankleshwar city.

Manali Patel, Chandresh Solanki, Tejas Thaker

### Large Strain Torsional Shear Tests on the Mechanism of Long-Distance Flow Slide in Palu, Central Sulawesi, Indonesia

The catastrophic flow slide in Palu city has proven that surface ground could laterally deform in several kilometers due to the earthquake motion even though the ground inclination is very gentle (1–5%). This paper aimed to understand the flow deformation behavior of Toyoura sand and flow sand samples collected from Sibalaya trench No. 3 in the modified hollow cylindrical torsional shear apparatus by using the water-inflow concept. Static liquefaction tests with constant shear stress are employed to identify the possibility of the specimen to flow under small initial static shear in drained conditions. In comparison, using the same field sand sample, an undrained cyclic test followed by monotonic loading is conducted to observe the specimen behavior under the undrained condition. It is observed that continuous flow behavior can be observed under small initial static shear stress with water-inflow concept. The continuous flow behavior of the sand specimen is defined by the initial density, which also affects the volume expansion behavior. The static liquefaction test using flow sand sample shows that this material could flow under the water-inflow mechanism. As a comparison, this material shows non-flow behavior in the typical undrained test, and even the specimen is liquefied.

Risqi Faris Hidayat, Takashi Kiyota, Muhammad Umar, Hasbullah Nawir

### One-Dimensional Soil Column Simulation on Water Film Formation During Earthquake

The 2018 Sulawesi earthquake of magnitude Mw 7.5 triggered large-scale flow slides and ground liquefaction in the Palu Valley at multiple locations on a ground of very gentle gradient. Findings of the post event forensic geotechnical investigation conducted by the authors of this research highlighted the presence of silty clay or sandy clay layers sandwiched between sandy or sandy gravel layers at multiple locations in the flow slide zones. These sandwiched layers tend to have low permeability as compared to overlying and underlying layers sandy strata. To study the contribution of these sandwiched layers on the triggering of flow slides, a preliminary research was conducted using 1D soil column with clay and non-plastic fines sandwiched between sand layers. The findings highlighted that the excess pore water pressure reached its peak value by an instant shock. A thin interlayer water called water film is easily formed below the clay and non-plastic fines seam on impact. The influence of water film on pore pressure dissipation and overall soil settlement was studied. Water film formed beneath the clay and non-plastic seam permits the soil layer above it to float, with continuous deformation in soil due to change in equilibrium condition.

Divyesh Rohit, Hemanta Hazarika, Chengjiong Qin, Tsubasa Maeda, Takaji Kokusho, Yuichi Yahiro

### Risk Assessment of Landslide Disaster for Detecting Isolated Communities in Wakayama Prefecture After Nankai Trough Earthquake

Isolated communities after earthquakes face severe problems, such as rescue delays and a lack of daily necessities due to prolonged times required for these to reach isolated areas. It is crucial, especially in mountainous regions, to take countermeasures for slopes that would cause an isolation problem with high probability. Therefore, we proposed an estimation methodology for detecting the isolated communities in mountain region using the slope failure probabilities during earthquakes. In this process, the slope failure probability was calculated using disaster prevention Karte and stability survey tables recorded by every road administration in Japan as well as the peak ground velocity and slope angles. Subsequently, the interruption probability for each road was estimated according to the calculated slope failures. The validity of the proposed method was verified by comparing it with road regulations that came into effect after the 2004 Niigata-ken Chuetsu earthquake. The proposed method was applied to the emergency route in Wakayama Prefecture during a Nankai Trough mega scenario earthquake, and the road interruption probability was subsequently calculated. Furthermore, we showed a case study of detecting slopes that should be taken countermeasures with priority among the fragile slopes along two major routes and demonstrated the effectiveness of the proposed methodology.

Katsuki Hozumi, Hisakazu Sakai, Yoshio Kajitani

### DCM Columns and PVDs Hybrid Ground Improvement for Embankment Construction

A case history of embankment construction on soft clay deposit improved by a combination of deep cement mixing (DCM) columns and prefabricated vertical drain (PVDs) installation method was simulated and investigated by finite element analysis (FEA). The function of the DCM columns is to control the settlement and lateral displacement under the toe of the embankment, and the function of the PVDs is to accelerate consolidation rate for a zone under the central of the embankment. For this case, only the surface settlements were measured, and the simulations agree with the measured data well, while the results of FEA give relative large lateral displacements under the toe of the embankment with a value of about 370 mm. Further numerical investigation was carried out assuming part of the preloading load was vacuum pressure, with which to result in the similar final surface settlement. The numerical results indicate that with the vacuum pressure, the lateral displacement under the toe of the embankment as well as the maximum compressive stress in the columns can be reduced significantly. These results indicate that combination of DCM columns and PVDs installation with vacuum pressure as part of preloading pressure can be an effective and economic ground improvement method for embankment construction on soft clay deposit.

Junfeng Ni, Jinchun Chai

A 1 g shaking table testing program was conducted to assess the dynamic performance of an innovative cost-effective countermeasure technique for new and existing road embankment on a liquefiable foundation subjected to cyclic sinusoidal loading. The model was shaken with a scaled earthquake motion having peak base acceleration of 0.2 g and 0.3 g in the first and second events which simulate the foreshock and mainshock of the 2016 Kumamoto earthquakes. In a series of four different shaking table model tests, the dynamic response of the embankment was investigated first without, and then considering three countermeasure techniques: pile supported embankment, connected piles-geogrid system supported embankment, and hybrid pile system supported embankment. The mechanism of remediation and performance of each proposed countermeasure techniques are discussed based on dynamic response of embankment. The effectiveness of each technique on preventing the development of pore water pressure and limiting the deformation of embankment was studied in this research. The hybrid pile supported system was found to be effective in maintaining the overall stability of embankment during earthquake loadings.

Chengjiong Qin, Hemanta Hazarika, Siavash Manafi Khajeh Pasha, Hideo Furuichi, Yoshifumi Kochi, Daisuke Matsumoto, Takashi Fujishiro, Shinichiro Ishibashi, Naoto Watanabe, Shigeo Yamamoto

### Evaluation and Short-Term Test on Potential Utilization of Ground Source Heat Pump for Space Cooling in Southeast Asia

The demand for air conditioning in Southeast Asia has increased in recent years owing to rapid economic growth in the region. On the other hand, power generation still relies on fossil fuels. A ground source heat pump (GSHP) is an alternative to reducing the energy required for cooling and heating in many countries. The use of a GSHP in a tropical climate like Southeast Asia is mainly for cooling (i.e., heat rejection), and the temperature differences between soil background and atmosphere are low throughout the year. This paper addresses the potential use of GSHP in Southeast Asia based on short-term performance data. Four GSHP systems have been installed in Thailand and Vietnam. Data gathered from the short-term operations provides important insights on GSHP performance. A comparison with an air source heat pump (ASHP) indicates that a GSHP installed at the Bangkok, using two vertical ground heat exchangers (GHEs), achieves a maximum of 33% electricity reduction. Similarly, GSHPs installed at the Saraburi site using horizontal GHEs achieves a maximum of 18.5% and 40.3% less electricity during highest and lowest temperature seasons, respectively, compared with an ASHP. The results also show that parallel–series arrangement improves the thermal performance than those of series–parallel arrangements. Considering the wide temperature climate range of Hanoi, a GSHP can also be used for heating purposes during a short winter period. While the short-term results discussed in this paper suggest the potential use of GSHP in Southeast Asia, further long-term analysis, cost evaluations and system optimization are required.

Arif Widiatmojo, Yutaro Shimada, Isao Takashima, Youhei Uchida, Srilert Chotpantarat, Punya Charusiri, Juraluk Navephap, Trong Thang Tran

### Experimental Study on Strengthening Near-Surface of Slopes Using Bio-grouting Technique

Near-surface instability due to incessant rainfall events poses challenges to the maintenance of earth structures. Bio-grouting (also be referred to as microbial induced carbonate precipitation (MICP)) is a recently emerged soil improvement technique, revealing high potential for stabilizing near-surface of slopes. The technique promotes the cementation of embedded soil using calcium carbonate that precipitates biochemically. This paper presents a bench-scale experimental program, and the objectives were (i) to understand how the treatment protocols impact the strengthening of near-surface and (ii) to assess the profile of treated slope. For those, a series of slope models was treated by various experimental protocols using surface spraying technique. During the treatment, bacteria culture and cementation resources were sprayed in two subsequent phases. The findings suggest that the bio-grouting responses vary depending on volume of cementation solution supplied. High supply of cementation solution developed a highly nonuniform-treated profile compared with low supplies. Also, 1 mol/L concentration of cementation solution is found to be the optimum for the treatment, providing strong intergranular bridging. The spatial distribution of calcium carbonate showed the treated slope can be considered into three layers: surface-crust layer, cemented soil layer and uncemented soil, suggesting that the application technique may provide erosion protection via the crust formed along the outer surface of the slope and cemented soil material formed on the interior.

Sivakumar Gowthaman, Kazunori Nakashima, Hiromi Nakamura, Satoru Kawasaki

### Sustainable Improvement Technology for Soft Grounds—The Geo Drain SPD Method

We will introduce the effectiveness of Geo Drain SPD method, which is an advanced vacuum consolidation method that reduces usage of the amount of finite natural resource by using biodegradable materials, based on construction example and laboratory tests.

Hironobu Iitsuka, Yoshiki Nara

### Development of a Junior High School ESD Program to Raise the Disaster Prevention Awareness Based on the Experience of Heavy Rainfall in Lowland

In this study, we developed a public junior high school ESD program to increase awareness of disaster prevention from heavy rain experiences. The theme of this program was “What is the phenomenon caused by heavy rain in our town? What are the issues to be improved?”. In this program, we constructed an inquiry learning consisting of production activities and presentation activities. By this program, we taught to increase disaster prevention awareness of students. From the results of the questionnaire survey, awareness of disaster prevention was raised, and motivation to contribute to the community was recognized.

### River Education on Sustainability and Disaster Prevention at Elementary Schools in Island Regions

The participation of elementary school students studying in the area is important for the sustainability of the area. This paper is a practice of an elementary school in Tsushima City, an island region of Japan. Two years ago, elementary schools have been conducting river education through collaborative learning. Through river education, elementary school students were able to understand that the river was clean, the extent of the brackish water area was discovered, the river business was understood, and salt damage was understood. We believe that river education will lead to disaster education as a result. Also, elementary school children want the water they use as drinking water to be clean forever, and they can imagine their future life from the perspective of disaster prevention. It was revealed that such elementary school students’ understanding contributes to regional sustainability.

Hidefumi Hatashima, Satoquo Seino

### Instrumentation for Disaster-Affected Reinforced Slopes in Uttarakhand, India

Landslide at Birahi in Chamoli district of the Lesser Himalayas in India had affected traffic safety along National Highway NH-58. Geotechnical and geophysical investigations were done to evaluate the causes of failures and to develop remedial measures. A slide-zone area of overburden with boulders was identified which matches with the borehole data for analyzing the probable causes of failure. Remedial measures adopted for this unstable stretch including drainage network implementation, erosion control measures, nailing on the hillside with facia, and a very tall unique retaining structure, i.e., 25 m high reinforced soil system with flexible facia on the valley side of slide area are briefed in this paper. However, the focus of the paper is on the illustration of how displacement and pressure distribution behavior of composite reinforced soil system of 25 m high installed is getting monitored through field instrumentation. The maximum displacement values are calculated using the empirical formula suggested by FHWA-NHI-10-024 guidelines. The paper also mentions about the numerical analysis of reinforced soil structure using Plaxis software. The displacement values from the results of Plaxis software analysis are reported and compared with the values obtained from empirical formulas of FHWA-NHI-10-024 guidelines.

Minimol Korulla, K. S. Beena, Pankaj Kr. Mourya

### Proactive Conservation of Main Tower of Bayon, Angkor, Against Global Warming

This paper describes the special characteristics of the ancient temples in Angkor in terms of geotechnical points of view, which have never been mentioned in the past because simply the soils and foundations have never been studied. Japanese Government Team for Safeguarding Angkor (JSA) introduced the study of soil and foundation. The heritage structure of Bayon in Angkor stands upon shallow direct foundation. The high main tower stands upon manmade fill of 14 m in thickness without special supporting such elements as piles. The amazingly strong strength of the manmade fill that had made to support heavy stone structure is the one of the character-defining elements of the authenticity of the foundation of Bayon in Angkor Thom. If the sand fill shows the shear strength of the common sandy, the fill could not keep standing safely under the rainy season in the south Asian region of the squall with heavy rain for the last 700 years since thirteenth century. To preserve the main stone tower, the paper proposes a simple method to cover the surface of the fill of the mound with impermeable layer to prevent the failure of the sand filled mound from the anticipated long and heavy rain in the coming global warming.

Yoshinori Iwasaki, Mitsuharu Fukuda, Mitsumasa Ishizuka, Takeshi Nakagawa

### Groundwater Level Changes in the Coastal Construction Site of Coal-Fired Power Plant, Cilacap, Indonesia; Natural or Construction Effect?

The construction of power plant with the capacity of 1000 MW in the coastal area of Cilacap, Central Java, Indonesia, started from October 2017 until 2019. The construction is started by excavating the area at least 8 m of depth to build the foundation and underground cooling tunnel. During the dry season in 2018, community who live around the construction site reported groundwater level depletion in their wells. The power plant authority argued that groundwater extraction for shrimp ponds along the beach is also responsible for the groundwater level depletion in the region. This study aims to determine whether groundwater level declining in this area caused by natural conditions or due to construction activities. Field observations were carried out both in the rainy and dry seasons in 2019. It consisted of groundwater level measurement, resistivity measurement, and inventorying the utilization of groundwater. Groundwater modelling used to simulate the impact of groundwater extraction and construction of the power plant towards the groundwater flow around the construction site. The results suggested that seasonal difference within a year affects to the declining of groundwater level of 1.06 m by average at the community’s wells and the whole research area, while the dewatering practices by the power plant authority around the construction site of foundation and underground cooling tunnel were responsible to the declining of groundwater level of 1–2 m limited 500–700 m from the construction site.

Doni Prakasa Eka Putra, Rilo Restu Surya Atmaja, Fania An Nisaa, Kurnianto Dwi Setyawan, Pramono Hadi

### Landslide Susceptibility Assessment in Trenggalek, East Java, Indonesia: A Geological Overview

The number of landslide occurrences in Trenggalek tends to increase every year, and it represents a significant constraint on development, causing high levels of economic loss and substantial numbers of fatalities. A complete understanding of geological conditions is essential needed for spatial planning and to reduce the risk of lost lives and infrastructure damage. Surface mapping at regional scale comprised of lithology, geomorphology, geological structures, and land-use conditions was conducted in an area of 1261 km2 to develop a detailed landslide susceptibility map. The surface mapping showed that landslides commonly occurred on steep slopes of the fault-controlled hills that having inclination ranging from 16° to 28°, in the areas covered by residual soils of Mandalika Breccia unit, with high geological structure density in the settlement areas. The high susceptibility zone covered 46,75% of the research area and was characterized by having slope inclination ranging from 8° to 45°, geological units of Mandalika Breccia and Arjosari Sandstone, and land uses of settlement, dry fields, and plantation. Undisturbed soil samples collected from the high susceptibility area exemplify the clay–silt material, and XRD analysis showed the dominant clay mineral composition of halloysite and smectite. Major ion components from precipitation water, seepage, and surface water samples were used to determine hydraulic connectivity in high susceptibility zone. Both seepage and surface water indicate sodium bicarbonate-type water similar to the chemical composition of the precipitation water. The landslide mechanism in the research area is mainly controlled by lithological conditions and triggered by high rainfall.

Wahyu Wilopo, Egy Erzagian, Diyaning Ratri, Teuku Faisal Fathani

### Riverbed Fluctuation Analysis of Small Rivers Equipped with Stream Barb Groins

Streambed degradation significantly affects riverbanks, causing various problems such as unstable flood control. Stream barbs are therefore, used for streambank stabilization; they are low-height masonry groins placed from the riverbank to the upstream side and are intended to mitigate riverbed degradation as a form of river flow control. In this study, the effect of stream barbs installed in 2018 in the Tagawa River in Nagano Prefecture, Japan, was investigated via riverbed fluctuation analysis using International River Interface Cooperative software. A terrain model for simulation was created using a computer-aided design river section view, and a hydrograph for May to December of 2018 was calculated from the stage discharge curve (H-Q curve). The Tagawa River was assumed to have a four-stage peak flow rate (maximum of 160 m3/s), with a design discharge of 410 m3/s. The analysis confirmed that regardless of the peak discharge scale, sedimentation of soil occurs at under 30–20 m3/s corresponding to the gradual decrease curve of discharge. The fluctuation analysis results were compared with drone-captured images from January 2019, whereby the flow meandering conditions of watercourse formation, sedimentation of soil, and scouring sites were determined. Overall, the simulation results were confirmed to agree closely with the images. It was also confirmed that the new side bar generated via the barb construction is effective in maintaining the sediment and preventing the decline of the riverbank against flooding at the scale at which the sidebar was generated, although the scouring becomes deep during flooding.

Mizuki Sakai, Yugo Hashimoto, Eiji Matsushita

### The Mechanism of Riverbank Erosion Caused by Ship-Generated Waves Along Hau River’s Entrance Navigation Channel, Southern Vietnam

From the past, earning living of the people in the lower of Mekong River has been acquainted with the ships and boats in the density river system. Gradually, waterway has become the key factor for area developing, intensity of commercial, and recreational navigation. Inland movement of the cargo ship brings a significant efficient on cargo shipping which impulses the regional economic development. However, impacts from inland movement should be considered seriously. The drawn followed by ship movement put a pressure on the riverbanks which causes turbulence and erosion potentially. This paper carried out several field measurements on bank structures and ship movements to assess the potential impacts of ship-induced wave on Hau River’s entrance navigation. As results, the riverbanks could resist the external shear stress by maximum wave height from 40 to 60 cm.

Son Huu Nguyen, Tin Trung Huynh, Vinh Trong Bui, Ngo Van Dau

### Battery-Less Infrastructure Monitoring Sensor Platform

In Japan, the construction of extensive infrastructure such as roads, railways, airports, energy plants, and so on, became popular from the 1960s when the period of high economic growth began, and high-level investments continued for about 40 years. Recently, infrastructure serious accidents have occurred, which is caused by aging or lack of inspection are of significant social concern. Therefore, as the population declines in the future, infrastructure monitoring using wireless sensor networks (IoT, Internet of things) is an urgent issue. On the other hand, the power supply is indispensable for driving the sensor device and transferring data. In this research, focusing on microwaves (electromagnetic waves) radiated from broadcasting and/or telecommunication that have been rarely reused, a battery-less infrastructure monitoring sensor platform that uses electromagnetic waves as a power source is realized. The proposed system is composed of a circularly polarized wideband planar antenna, rectifier circuit with impedance matching circuit, sensor module and Bluetooth low energy (BLE) module. For the feasibility study, the temperature and humidity sensors are attached on the surface of a concrete block, which is the model of the infrastructure. The 920 MHz RF signal is injected into the receiving antenna as a power source. The data of the temperature and humidity are transmitted to the smartphone or laptop computer at every 2-s interval. We can obtain the battery-less infrastructure monitoring sensor platform.

Haruichi Kanaya, Mohamed M. Mansour, Shunsuke Hatanaka, Ataru Nakashima, Osamu Takiguchi

### Developing a Sustainable System for Early Warning Against Landslides During Rainfall

Landslides have been occurring frequently because of rainfall, which leads to serious consequences, often plugging rivers, disrupting transportation, communication, and other lifeline projects and posing a serious threat to people's life and property. Therefore, effective early warning system for rainfall-induced landslide is particularly important. This research presented the development of early warning system that includes soil moisture sensor, temperature sensor, and data transmission system. Some tests were carried out to evaluate the feasibility of the developed system under different water contents. Test with different sample depths under the same water content was also used to verify the accuracy of this system. The results show that, the sensitivity of the sensor is affected by the initial state, and it takes about 10–20 min to reach the stable measurement state. With the increase of water content in soil samples, the resistance value obtained by the system decreases accordingly, which is consistent with theoretical results. The tests of early warning system also worked well under different depths of the same soil sample. The development of the current warning system is the basis for predicting landslides in the future, and lower development costs and accurate test results make it possible to be widely adopted to both the developed and developing nations.

Yan Liu, Hemanta Hazarika, Osamu Takiguchi, Haruichi Kanaya

### Evaluation of Slope Failure and Driftwood Disaster Susceptibility Zone Using Geo-spatial Information

From July 5 to 6, 2017, the heavy rain in the northern Kyushu causes flooding and landslide. It also severely damages the surrounding forests, farmland, and even urban area after falling trees from hillside flowed into the rivers. Therefore, this paper selected the river area with lots of driftwood in Asakura City and Toho village in Fukuoka as the research area. Slope failure, one of the causes of driftwood, was obtained through analysis. The susceptibility zone was evaluated by using the SVM model, and the characteristics distribution of influencing factors was described using GIS. The aim is to provide useful basic information for the prevention and mitigation of driftwood disasters and forest maintenance in the future.

Lu Tian, Yasuhiro Mitani, Yuki Okajima, Hisatoshi Taniguchi, Taiga Tabuchi

### Change in Shear Wave Velocity During Consolidation and Undrained Cyclic Loading on Cemented Sand

Concerns have been raised that future intense earthquakes in Japan will cause liquefaction in Pleistocene deposits beneath critical infrastructure facilities such as nuclear power plants or highways, which have not been examined by the current liquefaction assessment. In order to assess accurately in-situ liquefaction characteristic of Pleistocene deposits, shear wave velocity, $$V_{s}$$ V s was introduced to quantify the effect of cementation on liquefaction characteristics. In this study, consolidation and undrained cyclic loading was applied to lightly cemented specimens while $$V_{s}$$ V s is continuously measured to verify whether strengthened soil fabric degrades or not. From the results during consolidation, although the specimens with cement addiction rate, C = 1% has a higher value of stress dependency, the ones with C = 3 and 5% have a value lower than that of the non-cemented specimens. After simple nonlinear regression was conducted, the result revealed that higher cemented specimens could become hard to deteriorate soil fabric during undrained cyclic loading, although non-cemented specimens maintained its soil fabric and lower cemented specimens declines it.

Masataka Shiga, Takashi Kiyota

### Contribution of Geotechnical Engineers in Restoration After Large-Scale Earthquake Disaster—Example of Aso Ohashi Bridge Replacement Project

For the plan and design of a bridge crossing an active fault, the design including alignment change or consideration of the fault displacement can be possible by knowing the fault location with a certain accuracy by the soil investigation. This paper presents ① detection of the active fault zone, ② evaluation method for the fault activity based on ground conditions, ③ evaluation method for the excavation stability behind the bridge pier, and shows the technical knowledges obtained by a series of soil investigations for the restoration of Kumamoto Earthquake disaster.

Koji Yamashita, Shingo Tanaka, Takefumi Yamaguchi

### Liquefaction Evaluation of Residential Land Using Geophysical Survey

Damage such as settlement and tilting of detached houses due to ground liquefaction has often been observed during recent earthquakes. In order to achieve the safe and sustainable residential environment, ground surveys are necessary to predict the damage due to ground liquefaction. However, it takes a long time and needs hard work to conduct conventional survey works. Alternative quick and accurate survey techniques are therefore required. In this study, we focused on the surface wave and passive linear array surveys, which are common geophysical survey methods. The surface wave survey can tell us the ground stiffness over the wide range. The latter one can give us the information from the ground surface down to a substantial depth. These survey techniques can give us the ground conditions more extensively and more quickly than conventional ones. From this background, we carried out geophysical explorations in Christchurch, New Zealand, where the earthquake on February 22, 2011 caused a lot of damage to detached houses due to ground liquefaction. The risk of liquefaction was then evaluated based on survey results. The evaluation methods using the FL and PL values were used for judging the liquefaction risk. As a result, the high liquefaction risk in severely damaged areas was reproduced in a short time by the results of surface wave and passive linear array explorations.

Shotaro Higuchi, Atsushi Yashima, Yoshinobu Murata, Keizo Kariya, Hiroshi Yokawa