Earthquake poses significant threat to offshore and marine structure. Many earthquakes in past have shown that local site conditions significantly affect the intensity of earthquake and so to the damages caused by those earthquakes. This study involves the seismic site characterization and ground response analysis of an offshore site in Western Yemen, based on extensive field test results and results of large number of laboratory tests on undisturbed samples. Large number of seismic cone penetration tests (SCPT) were conducted as field test analysis for site characterization and evaluation of low strain soil stiffness. Dynamic properties such as shear modulus and damping ratio of soil samples corresponding to very low to high strain level were established based on laboratory tests. Peak ground acceleration (PGA) was evaluated using the generated synthetic ground motion. This study also gives a site specific design response spectrum based on Eurocode, corresponding to 475 and 2500 year return period.

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Mitigation of natural disasters is one of the most important missions of engineers. While heavy rains and earthquakes are striking to our community, geotechnical engineers can make good contributions to mitigate those disasters. The present paper addresses several difficulties encountered in operation of disaster-mitigative infrastructures. It is important as well to maintain those measures. On the other hand, deeper knowledge on the causative mechanism of disaster is indispensable in order to improve the level of disaster mitigation. Finally engineers should try to foresee the future situations and be prepared for them. The required time is often very long. These issues are discussed in this paper by referring to examples and experiences.

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Design of pile foundations coupled with vertical and lateral loads under earthquake conditions in both liquefied and non-liquefied soils have been addressed in the present study with inclusion of recent advancement in research. Starting with pseudo-static analysis of a pile embedded in non-liquefied and liquefied soil, an analytical procedure based on finite element approach to determine the bending moment and lateral deflection of piles at various depths and normalized moment amplification factor for different l/d ratios have been evaluated. Dynamic analysis of the pile is implemented by using finite difference based FLAC3D program and different ground motions are applied at model base to obtain the complete couple behavior of piles subjected to vertical and lateral loads. Necessary steps for modern design of piles in seismic areas with a case study of pile foundation for oil tanks in Iraq have been presented to highlight the significance of dynamic soil properties, site-specific ground response, liquefaction analysis in addition to behavior of piles as stable foundation system.

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Large-scale liquefaction was caused by the 2011 off the Pacific coast of Tohoku, Japan, earthquake and many pipes in the liquefied ground suffered serious damages. One of the issues pointed out after the earthquake is the dynamic behavior and the mechanism of pipes near a structure in the liquefied ground. This study focuses on evaluating the dynamic behavior through centrifuge model test. Test results show that the uplift of pipes in the liquefied ground occurred during an earthquake and liquefaction happens at that time. After an earthquake, pipes start to sink with increasing effective stress. The characteristic of damage mechanism depends on the depth of pipes and the state of ground (in liquefiable layer, at ground water level, or in the unsaturated layer). The data also shows that the direction of force interacting pipes during liquefaction was only bending direction. So we should reconsider the design criteria for pipes which is widely used in Japan applying to axial force.

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Seismic resilience of retaining wall with different sand – tire chips (STC) mixtures as backfill materials has been investigated. This paper presents the results of 1g-shaking table model tests carried out on retaining wall models of 600 mm height backfilled with different proportions of STC mixtures. The test program used two types of scaled earthquake input motions: Sikkim and South Napa. Model walls behaviours are presented in terms of incremental earth pressures acting on the wall and the associated displacements, as well as the accelerations at various locations of the model wall. Physical model test results revealed that the seismic incremental earth pressures, wall displacements, and accelerations were significantly reduced by using STC mixtures as backfill materials. Based on experimental model results, STC mixture backfills showed higher seismic resilience behavior compared to that of with conventional sand backfill.

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This study proposes to develop a low cost damping scheme using soil and waste tyre crumb mixture for low to moderate rise buildings. The proposed study consists of two parts, first characterizing soil and waste tyre mixtures and finding out the optimal size of tyre crumbs. The second part is to design the isolation system for low to moderate rise buildings and determine optimum dimension of the system. In the first part, a series of Unconsolidated Undrained triaxial test and large scale direct shear test have been carried out to select the optimum size of tyre crumbs from seven different crumb sizes. The Rubber Soil Mixtures (RSM) sample that provides higher shear strength, energy absorption capacity and stiffness is considered as the optimal size and further used in numerical simulations. In the second part, to analyze the damping effect of RSM, extensive numerical simulations have been carried out on the soil-foundation-structure system with varying thickness of RSM around isolated footing, varying percentage of rubber in RSM and input time history. The reduction in shaking level in terms of acceleration and inter storey drift, at different floor level with the use of RSM can be reduced by 40 to 50%.

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This paper presents a study on slope-covering method, which is frequently used in Japan as a reinforcement measure against seepage failure of river embankments. Covering the face of the riverside slope with impervious materials (impervious soil, concrete, impervious sheet, or other artificial materials) prevents the river water from penetrating into the embankment. In this study, a series of model experiments and numerical seepage analyses were performed to clarify the prevention effect of this method. From the results, it is clear that covering the slope is effective not only in delaying the rising speed of local hydraulic gradient at the slope toe, but also in reducing the hydraulic gradient. The numerical analyses showed that this method is more effective when used on steeper slopes. However, the reinforcing effect is drastically reduced when the water level exceeds the area of the slope covered.

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This paper evaluates the significance of nail reinforcement, influence of nail inclination and facing material type on the stability and deformation behaviour of soil-nailed slopes subjected to seepage. Centrifuge model tests were carried out at 30 gravities on model slope (5V:1H) with horizontal back slope having slope height of 7.2 m, soil nails spaced at 2.1 m x 2.1 m. All slope models were instrumented with pore water pressure and displacement transducers and markers were digitized to arrive at displacement vectors with rising ground water table within the slope during centrifuge tests. In addition, the center column of soil nails were instrumented at their mid-length to measure nail forces at the onset of seepage flow during the centrifuge test. An unreinforced slope was observed to fail once the seeping water reaches the toe of the slope. In comparison, soil-nailed slopes were found to stable at the onset of seepage. Soil-nailed slope with soil nails inclined at 10° was observed to perform better than a slope stabilized with soil nails inclined at 25°. A soil-nailed slope with an aluminium facing was found to sustain large settlements as compared to fiber-blended plaster of Paris facing at the onset of seepage. Finally, an attempt has been made to compare results of stability analysis of centrifuge model slopes with and without soil-nails.

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Tsunami waves generated by the 2011 off the Pacific Coast of Tohoku Earthquake caused catastrophic damage to waterfront structures, such as breakwaters and sea walls. Countermeasures of compound disaster by future mega earthquake such us, Nankai megathrust earthquake and subsequent tsunami, are issues that should be resolved urgently. Therefore, the authors developed reinforcing technique of breakwater foundation using steel sheet piles and gabions that can minimize damage subjected to the tsunami higher than the design tsunami level. In this research, hydraulic model tests were performed to evaluate tsunami resistant characteristic of proposed reinforcing technique. Results of this research revealed that the settlement and the inclination of the caissons during tsunami could be significantly reduced by the proposed reinforced reinforcing technique.

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As a crucially important issue that Asia–Pacific region residents are currently confronting, this paper treats the increasing probability of unusual and extreme natural disasters that continue as a consequence of climate change, combined with sea-level rise (SLR). Calculated inundation areas in low-lying regions in Thailand are visualized using a geographical information system (GIS). Results suggest that the effect of SLR on increasing inundation is more remarkable than that of land subsidence. Therefore, appropriate adaptation measures must be undertaken in the respective regions to avoid enormous losses and damage from inundation that are expected to derive from the effects of SLR combined with land subsidence.

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The structure has to be socketed into hard strata to enhance the efficiency of load carrying capacity for a substructure carrying heavy lateral load. In case of non-displacement piles, drilling the hard strata is a time consuming and expensive process. A system of experimental program was conducted on an instrumented model pile to study the behaviour of pile socketing under lateral load by varying its depth of socketing and the free standing height of pile above the ground level. The experimental results showed that increasing the depth of socketing significantly increases the lateral load carrying capacity of pile. At 3D depth socketing with 800 mm (Le/L=33.33%) free standing height, the capacities of 38.1 mm and 50.8 mm diameter piles were increased respectively by 4 and 8.23 times the capacity of 25.4 mm diameter pile. Compared with pile bearing over hard strata, socketing the pile into hard strata reduces the lateral displacements substantially

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Solid waste materials in improper disposal sites or illegal dumping sites contain various types of materials. Mechanical property of solid waste materials has not been clarified sufficiently due to its complex composition. In this study, in-situ direct shear and permeability tests were performed for calculating slope stability of solid waste deposit in Japan, where the large crack was occurred on the ground surface. Strength properties on solid waste material and original ground were obtained from the in-situ direct shear test. Permeability of the ground was also measured by in-situ permeability test. Influence of ground and water conditions on slope stability was discussed based on the calculation results.

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Geosynthetics have long been used for reinforcing unbound base/subbase layers in paved and unpaved roads for improving its performance and carrying more loads. Field applications demonstrated that geosynthetic reinforcement can help reduce various types of distresses and extend the service life of pavement structures. Geogrid, a two dimensional planar geosynthetic is used in unpaved roads to to carry the superimposed load such as traffic load and to well distribute the load safety to the subgrade. In the current paper experimental studies are conducted on geogrid reinforced Granular Sub Base to see the effectiveness of reinforcement in the field by allowing the load for very large number of repetitions. The performance of the reinforcement is monitored by studying the plastic and elastic deformation and then comparing it with the unreinforced cases. The results showed that geogrid reinforces the unbound aggregate thus reducing the deformation along with the reduction in the required thickness of the aggregate layer of unpaved roads. The amount of reduction of permanent deformation was more for reinforced layer with higher thickness.

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The recent increase in the generation and use of coal fly ash by electric power stations and various industries has contributed to Japan developing technology to facilitate the utilization of fly ash as ground material, including the use of fly ash for fills and embankments, pavement and subbase courses, subgrade stabilizations, landfill cover, soil improvement, land reclamation, slurried flowable ash and water pollution control. This paper describes the state of the art related to coal fly ash utilization as geo-material in Japan. In particular, this paper describes the material properties and technology associated with each technique. As coal fly ash contains a very small amount of heavy metal which should be considered for geo-environmental safety, this paper also discusses quality and inspection techniques for coal fly ash materials.

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One of the methods to create a stable working environment around tunnel and seal the tunnel periphery against underground water is artificial ground freezing. The method is economically beneficial at large scale construction sites, and long-term containment. It is also superior method when temporary high strength soil or temporary impermeable barrier is needed. In this study, application of freezing in shield tunneling is investigate. A case study of a comprehensive underground tunneling project in Tokyo suburb is considered. The construction includes a junction of main tunnel with a ramp way that connect underground tunnel route to the ground surface. In this construction site, connection segment of main route and ramp way need to be widen. Because of this enlargement and sequence of works below water table, temporary stable work front and hydraulically water proof zone is demanded. As an effective way of ground improvement, freezing method is used in this case. In this way, a parametric study is conducted and amount of horizontal and vertical freeze-thaw induced displacement and effect of soil stiffness around tunnel is estimated numerically. In addition, the effect of design parameters of intermittent freezing on the thickness of freezing zone is investigated. Results of analyses indicates that based on reliable design scheme, an energy-efficient plan for application of freezing in shield tunneling is possible.

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The present study reveals the effect of interaction of two closely spaced shallow circular plate anchors embedded in a homogeneous medium-dense sand bed subjected to identical loading conditions. The investigation has been carried out in a large scale laboratory testing facility where the size of the anchor plates is deployed in the range analogous to that generally used in the real field situation. It can be deduced that at a closer spacing between the anchor plates the uplift capacity of the anchors decreases as compared to that of an isolated anchor. This phenomenon is due to the intervention and coalescence of the failure plane of an anchor in the presence of the other anchor in its vicinity. The dimensionless uplift capacity factor has been introduced in order to understand the interaction phenomenon of two closely spaced anchor plates and its adverse effect on the design philosophy.

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In the current study, a review on the response of soils subjected to high strain rate loadingis presented. High strain rate loading on soil may be applied through high loading rate uniaxialcompression tests, triaxial tests, split Hopkinson pressure bar (SHPB) tests, and shock tube test.Herein, the results of SHPB tests from the literature have been reviewed and the effect of strainrate on the stress-strain response of soils, elastic modulus, initial inertia, peak and failure stressesof soils have been studied. The effects of strain rate, initial void ratio, confining pressure andsaturation on the high strain rate response of soils are also discussed. The review thus providescomplete understanding of soil behavior under high loading rates.

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Sand compaction pile (SCP) is a method of constructing large diameter sand columns in the ground. The process of SCP installation is known to affect the in-situ soil since it is compressed as the cavity expands to accommodate the sand pile. It is difficult to correctly capture these installation effects in 1g tests on the laboratory floor because of the scale effects. This paper compares the results of frozen pile method of installation at 1g to the in-flight method of SCP installation at high-g using the centrifuge. Pore pressure changes were recorded during the entire installation procedure. No setup of stresses was observed in 1g tests. However, in high-g tests, stress relaxation did not occur during the sand injection stage. The centrifuge test results were then compared to plane strain cavity expansion theory (CET). The findings seem to show that the CET gives a reasonably good estimate at large depth for the entire installation process but not for the residual stress after the casing jack-in during the first stage. Deviation from plane strain CET was also noted at shallow depths. These findings imply that in order to mobilize significant set-up of stress in the improved ground, there must be substantial further cavity expansion during the sand injection stage of SCP.

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Seismic dilatometer test (SDMT) was conducted in the Salt Lake campus of Jadavpur University, Kolkata using Marchetti’s SDMT equipment. Another location in Kolkata was chosen where alluvial deposits were encountered for performing liquefaction analysis by SPT method only. Using the usual correlations as mentioned in the report of the ISSMGE TC 16 on ground property characterization from in-situ testing (2001), oedometer modulus, undrained shear strength, friction angle and shear wave velocity profile were found out. In the same location, standard penetration test (SPT) was also carried out. Based on the field SPT values and visual soil classification, a sub-soil profile was delineated. Engineering properties of the various layers were determined from standard correlations available in the literature. It was observed that both the sub-soil profiles obtained from these two tests were more or less similar. In the present investigation, an attempt has been made to compare the results of these two methods viz., seismic dilatometer test (SDMT) and standard penetration test (SPT). Based on the small strain shear modulus from DMT as well as shear wave velocity profile from SDMT tests, an effort has also been made to determine the liquefaction potential and settlement of post earthquake condition of the sand layers using standard charts given by Ishihara and Yoshimine (1992). Besides, using the correlation between (N1)60 and volumetric strain (εv) as reported by Tokimatsu and Seed (1987), the same were obtained for SPT tests. Subsequently, comparison is made between results of these two methods. Finally, recommendations are made regarding the suitability of these two methods with particular reference to liquefaction potential and post earthquake settlements.

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Vertical hydraulic barrier in a coastal waste reclamation facility takes an important role to separate the waste from the sea environment. Steel companies and marine constructors have developed new technologies to meet the technical standard issued in 1998 as ministry ordinances in Japan. Although performance confirmation for joints of the vertical hydraulic barrier, mostly cutoff sheet pile wall, is important, it is impossible to confirm all of their joints. Therefore, it is useful if the performance can be confirmed through construction management data recorded during sheet pile installation. Objective of this study aims to propose a practical method to assure impervious performance of the joints. Development and proposal of the quality control method to ensure the impervious performance was attempted based on a previous study to find a correlation between performance confirmation for sampled joints and their construction management data. To identify sheet piles overloaded during installation, cross-sectional image of those data drawn along the sheet pile wall is useful in the quality control.

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The 2011 earthquake off the Pacific coast of Tohoku was the source of several geoenvironmental issues in the eastern region of Japan. Among these issues, treatment of disaster debris and utilization of treated materials in geotechnical applications is presented in this manuscript. Use of the treated disaster debris for the recovery of infrastructures has been conducted at the disaster affected areas, in particular at areas that suffered from subsidence. Current status of characterization, standardization, and strategic utilization of the recovered soils obtained from the disaster debris is also presented in this paper. This includes the contributions by the Japanese Geotechnical Society.

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