The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Kenji Harada - One of the best experts on this subject based on the ideXlab platform.
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effect of scp improvement geometry on mitigation of liquefaction induced embankment settlement
2020Co-Authors: Yang Li, Masaki Kitazume, Akihiro Takahashi, Kenji HaradaAbstract:Liquefaction of foundation soil attributes significant damage to infrastructures. The Sand Compaction Pile (SCP) method is one of the countermeasures against liquefaction to densify the ground by installing dense Sand Piles. Recently, an innovative method which can install the Sand Piles at various geometric form into the ground has been developed. However, the effects of the geometric form on the response and deformation behaviour of the improved ground are not well understood. The authors have studied the effects of SCP improvement geometric form on seismic behaviour of ground and embankment by centrifuge tests and numerical analyses. In this manuscript, the results of numerical analyses are presented, where it indicates that the SCP geometric form influences the deformation mode and related settlement of ground. Additionally, it is suggested that it has an optimum improvement geometric form for mitigating embankment settlement in certain ground conditions.
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characteristics of liquefaction in tokyo bay area by the 2011 great east japan earthquake
Soils and Foundations, 2012Co-Authors: Susumu Yasuda, Kenji Harada, Keisuke Ishikawa, Yoshiki KanemaruAbstract:Abstract The 2011 Great East Japan Earthquake caused the severe liquefaction of reclaimed lands in the Tokyo Bay area, from Shinkiba in Tokyo through Urayasu, Ichikawa and Narashino Cities to Chiba City. However, the reclaimed lands that had been improved by the Sand Compaction Pile method, the gravel drain method or other methods did not liquefy. The reclaimed lands that did liquefy had been constructed after around 1966 with soil dredged from the bottom of the bay. The dredged and filled soils were estimated to have been liquefied by the earthquake. Seismic intensities in the liquefied zones were not high, although the liquefied grounds were covered with boiled Sand. Most likely it was the very long duration of the main shock, along with the large aftershock that hit 29 min later, which induced the severe liquefaction. Sidewalks and alleys buckled at several sites, probably due to a kind of sloshing around of the liquefied ground. Moreover, much Sand boiled from the ground and the ground subsided significantly because the liquefied soil was very fine. Many houses settled notably and tilted. In Urayasu City, 3680 houses were more than partially destroyed. Sewage pipes meandered or were broken, their joints were extruded from the ground, and many manholes were horizontally sheared. This remarkable damage may also have occurred due to the sloshing around of the liquefied ground.
Toni M. Weber - One of the best experts on this subject based on the ideXlab platform.
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Development of a Sand Compaction Pile installation tool for the geotechnical drum centrifuge
2015Co-Authors: Toni M. WeberAbstract:Sand Compaction Piles are used in practice for ground improvement of weak subsoil. These columnar inclusions improve the consolidation behaviour as well as reduce the compressibility of the soft ground. The current design procedure of these Sand Piles is based on simple empirical calculations, which do not take account fully of the Sand Pile behaviour. In order to gain a deeper understanding of the behaviour of Sand Compaction Piles, physical investigations are being conducted at ETH in Zurich. The basic system behaviour of soft soil and column is simulated physically by centrifuge modelling. Therefore a Sand Compaction Pile installation tool was developed and applied successfully in an initial test series. This allowed the stress paths encountered by the soil during the construction process of a displacement Sand Pile to be modelled realistically, because the stress situation in the soil changes significantly due to installation. The results of these first tests are presented in this paper. 1
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Centrifuge modelling of Sand Compaction Piles in soft clay under embankment load
2006Co-Authors: Toni M. Weber, Jan Laue, Sarah M. SpringmanAbstract:Sand Compaction Piles are used in practice for ground improvement of soft subsoil in order to accelerate consolidation, reduce compressibility, and increase strength. The current design procedure of Sand Compaction Piles is based on simple empirical calculations, which does not take full account of the Sand Pile behaviour. This research project investigates the behaviour of a base reinforced embankment constructed on a soft clay layer, which is improved with Sand Compaction Piles. In order to gain a better understanding of in-teractions within the structure, physical investigations are being conducted by means of centrifuge modelling. Tests were performed under plane strain conditions in a strong box, using a newly developed Sand compac-tion Pile installation tool for in-flight Pile construction. Initial analysis of test data shows the change in stress state due to Sand Compaction Pile installation and the influence on clay behaviour.
Yasuda Susumu - One of the best experts on this subject based on the ideXlab platform.
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Effective Stress Analysis for Evaluating the Effect of the Sand Compaction Pile Method During the 1995 Hyogoken-Nambu Earthquake
Scholars\u27 Mine, 2001Co-Authors: Miwa Shigeru, Nozu Mitsuo, Ozutsumi Osamu, Iai Susumu, Yashima Atsushi, Yasuda SusumuAbstract:The effect of the Sand Compaction Pile method as a countermeasure for liquefaction mainly consists of three factors: increase in the density, increase in the horizontal effective stress and stabilization of microstructure. Proper evaluation of the effect of improvement is important for estimating the seismic behavior of the ground improved by the Sand Compaction Pile method. How to incorporate the effect and its factors into an analytical model was investigated by simulating the seismic behavior of the ground at two sites during the 1995 Hyogoken-Nambu earthquake with the effective stress analysis method “FLIP.” It was found that not only the increase in the density but also increase in the horizontal effective stress were important in explaining the effect of the Sand Compaction Pile method. Moreover, a model taking account of both Sand Piles and the improved ground between them suggested a possibility of reproducing the behavior of improved ground under large ground motions more properly
Taehyung Kim - One of the best experts on this subject based on the ideXlab platform.
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stress sharing behavior and its mechanism during consolidation process in composite ground improved by Sand Compaction Piles with low replacement area ratio
Marine Georesources & Geotechnology, 2006Co-Authors: S K You, Kazuhiro Oda, Taehyung KimAbstract:In order to accurately design a Sand Compaction Pile (SCP) with low replacement area ratio, it is important to understand the mechanical interaction between the Sand Pile and clay ground and its mechanism during consolidation process in composite ground. In this article, therefore, a series of numerical analyses on composite ground improved by SCP with low replacement area ratio were carried out. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, were confirmed by comparing the results obtained from a series of laboratory model tests with the composite ground improved by SCP. Through the results of the numerical analyses, mechanical behavior of the Sand Pile and clay in composite ground during consolidation is elucidated, together with a stress sharing mechanism between Sand Pile and clay.
Hyun Young Shin - One of the best experts on this subject based on the ideXlab platform.
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analysis on the drain shear behavior of composite ground improved by Sand Compaction Pile with low area replacement ratio
Journal of The Korean Society of Civil Engineers, 2005Co-Authors: Hyun Young ShinAbstract:This study performed a series of consolidated drained triaxial tests to present the shear behavior of composite ground improved by Sand Compaction Pile with low area replacement ratio. Test samples were prepared with area replacement of 0, 9.59, 23.58, 38.7 and 100%. Tests were performed under the confined pressure of 98.1, 196.2 and 294.3kPa. Rate of strain s were controlled by 0.05, 0.2 and 1.0mm/min respectively. It was found that composite ground show peak and ultimate stress in stress-strain behavior. From test results, effect of confined pressure and rate of strain on the stress-strain behavior were investigated. Peak and ultimate stress could be quantified to the maximum stress of untreated clay ground. In addition, effective internal friction angles of the composite ground were found to have a nonlinear increase according to the area replacement ratio. Effective cohesions of composite ground, however, showed sharp drop after specific area replacement ratio.
