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centrifuge model tests on pile-reinforced slopes subjected to drawdown

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1290-1300页

作者： Sujia Liu Fangyue Luo Ga Zhang State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing100084China

Piles are generally an effective way to reduce the risk of slope ***,previous approaches for slope stability analysis did not consider the effect of the piles coupled with the decrease of the water level(drawdown).In this study,a series of centrifuge model tests was performed to understand the deformation and failure characteristics of slopes reinforced with various pile *** the centrifuge model tests,the pile-reinforced slopes exhibited two typical failure modes under drawdown conditions:across-pile failure and through-pile *** the through-pile slope failure,a discontinuous slip surface was observed,implying that the assumption of the slip surface in previous stability analysis methods was *** test results showed that drawdown led to instability of the piles in cohesive soil,as the saturated cohesive soil failed to provide sufficient constraint for *** slope exhibited progressive failure,from top to bottom,during *** deformation of the piles was reduced by increasing the embedment depth and row number of *** addition,the deformation of soils outside the piles was influenced by the piles and showed a similar distribution shape as the piles,and the similarity degree weakened as the distance from the piles *** study also found that the failure mechanism of unreinforced and pile-reinforced slopes induced by drawdown could be described by coupling between the deformation localization and local failure,and it revealed that pile-reinforced slopes could reduce slope deformation localization during drawdown.

关键词： Slope Pile Drawdown Failure Reinforcement centrifuge model test

Evaluation of seismic behavior of box culvert buried in the ground through centrifuge model tests and numerical analysis

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Underground Space 2019年第2期4卷 147-167页

作者： Hitoshi Yatsumoto Yasuo Mitsuyoshi Yasuo Sawamura Makoto Kimura Maintenance Division Hanshin Expressway Company LimitedJapan Obayashi Corporation Construction DivisionJapan Department of Civil and Earth Resources Engineering Kyoto UniversityJapan

Japan has yet to establish a seismic design for road box culverts(RBCs)because past major earthquakes did not damage *** recent years,structures with enlarged sectional dimensions(the purpose of which is to optimize the internal space in RBCs)have become ***,the unknown seismic strength of such large RBCs makes RBC seismic designs increasingly *** seismic design methods have been developed for and applied to rectangular underground structures,e.g.,cut-and-cover tunnels,which are structurally similar to *** these methods are applicable to RBCs,it is uncertain whether they can be applied directly because there are currently no evaluation results from model tests on RBCs,which have unique structural features,e.g.,no haunch at the bottom of the ***,we verify a seismic behavior of an RBC and develop a method for evaluating it in order to establish a seismic design for *** conducted centrifuge model tests subjected to seismic force and a numerical analysis using an elastoplastic finite analysis method,in addition,we validated this analysis by comparing the test and analytical *** test results show RBCs will most likely develop rocking rotation when the ground strain exceeds approximately 0.08%.A comparison of the numerical and experimental results shows that this analysis can estimate the shear deformation behavior with approximately 90%accuracy in square cross-section ***,this analysis has tendency to underestimate the axial forces in each case and to overestimate the bending moments of some members in the case of wide cross-sections.

关键词： Box culvert centrifuge model test Numerical analysis Shear deformation Rocking rotation

A modified generalized scaling law for the similitude of dynamic strain in centrifuge modeling

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 589-600页

作者： Ma Qiang Ling Daosheng Meng Di Kyohei Ueda Zhou Yanguo MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Institute of Geotechnical EngineeringCenter for Hypergravity Experiment and Interdisciplinary ResearchZhejiang UniversityHangzhou 310058China Disaster Prevention Research Institute Kyoto UniversityGokashoUjiKyoto 611-0011Japan

Soil strain is the key parameter to control the elasto-plastic deformation and even the failure *** overcome the defect that the strain of the model soil is always smaller than that of the prototype in Iai′s generalized scaling law(GSL),a modified scaling law was proposed based on Iai′s GSL to secure the same dynamic shear strain between the centrifuge model and the prototype by modulating the amplitude and frequency of the input motion at the base.A suite of dynamic centrifuge model tests of dry sand level ground was conducted with the same overall scaling factor(λ=200)under different centrifugal accelerations by using the technique of“modeling of models”to validate the modified *** test results show that the modified GSL could achieve the same dynamic strain in model as that of the prototype,leading to better modeling for geotechnical problems where dynamic strain dominates the response or failure of ***,the applicability of the proposed scaling law and possible constraints on geometry scaling due to the capability limits of existing centrifuge shaking tables are discussed.

关键词： deep deposit seismic response generalized scaling law centrifuge model test

Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

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Frontiers of Structural and Civil Engineering 2020年第6期14卷 1462-1475页

作者： Nabarun DEY Aniruddha SENGUPTA Department of Civil Engineering Indian Institute of Technology KharagpurKharagpur 721302India

Slope failure occurs due to an increase in the saturation level and a subsequent decrease in matric suction in unsaturated *** paper presents the results of a series of centrifuge experiments and numerical analyses on a 55°inclined unsaturated sandy slope with less permeable,stronger silty sand layer inclusion within *** is observed that a less permeable,stronger silty sand layer in an otherwise homogeneous sandy soil slope hinders the infiltration of *** water content of the slope just above the stronger layer increases significantly,compared to *** shear band is found to initiate in a homogeneous sandy soil slope,whereas for a non-homogeneous slope,they initiate just above the less pervious,stronger layer.A discontinuity of the shear zone is also observed for the case of a non-homogeneous soil *** factor of safety of a non-homogeneous,unsaturated soil slope decreases because of the less permeable,stronger *** decreases significantly if this less permeable,stronger soil layer is located near the toe of the slope.

关键词： non-homogeneous slope stronger soil layer factor of safety centrifuge model test unsaturated soils

Simplified method for analyzing soil slope deformation under cyclic loading

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1967-1976页

作者： Ga Zhang Yaliang Wang Fangyue Luo State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing100084China

Reasonable assessment of slope deformation under cyclic loading is of great significance for securing the safety of slopes. The observations of centrifuge model tests are analyzed on the slope deformation behavior under cyclic loading conditions. The potential slip surface is the key for slope failure and follows two rules:(i) the relative horizontal displacement along the potential slip surface is invariable at an elevation, and(ii) the soil along the slip surface exhibits the same degradation pattern. These rules are effective regardless of the location of the potential slip surface throughout the entire deformation process of a homogeneous slope, ranging from the initial deformation stage to the failure process and to the post-failure stage. A new, simplified method is proposed by deriving the displacement compatibility equation and unified degradation equation according to the fundamental rules. The method has few parameters that can be determined through traditional element tests. The predictions from the proposed method agree with the centrifuge test results with vertical loading and shaking table loading. This result confirms that the proposed method is effective in predicting the full deformation process of slopes under different cyclic loading conditions.

关键词： Soil slope Cyclic load Deformation centrifuge model test Slice method

Stability of long trench in soft soils by bentonite-water slurry

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Journal of Central South University 2014年第9期21卷 3674-3681页

作者：卓弘春杨宇友张子新潘春晖段创峰 School of Engineering and Technology China University of Geosciences (Beijing) Department of Geotechnical Engineering School of Civil Engineering Tongji University Shanghai Urban Construction (Group) Corporation

A series of centrifuge model tests exploring the effects of different types of slurry on long-trench stability in soft clay were conducted. The influence of groundwater conditions relative to trench stability was examined by constructing long trenches using different slurries. The soil deformation and surface settlement induced by the excavation of the trench are found to be closely related to slurry type and excavation depth of the long trench. Increasing the bentonite concentration of the slurry has beneficial effects on stability: 1) larger particles can improve local and global stability in cases where filter cakes do not form, and 2) larger viscosity can promote filter cake formation on the walls of long trenches excavated in soft clay and enhance their stability.

关键词： slurry trench soft clay stability centrifuge model test

centrifuge modelling of tunnelling below existing twin tunnels with different types of support

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Underground Space 2022年第6期7卷 1125-1138页

作者： Qian Fang Xiang Liu Kehan Zeng Xuedong Zhang Mozhen Zhou Jianming Du Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China College of Transportation Engineering Dalian Maritime UniversityDalian 116026China Western Investment Co. Ltd.of CCTEBChengdu 610041China China Institute of Water Resources and Hydropower Research Beijing 100038China

Tunnel excavation below existing tunnels produces ultimate and serviceability problems to the existing *** behaviours of induced stresses on the existing tunnels haven’t yet been fully *** this study,a centrifuge model test was adopted to investigate the effects of new tunnelling on two existing overlying *** existing tunnel model simulated a prototype composite lining tunnel and the other simulated a prototype segmental lining *** volume loss produced by new tunnel excavation was modelled by an in-flight actuator *** surface settlements,the existing tunnels settlements,the soil pressures on existing tunnels,the bending movements of existing tunnels,and the joint behaviours of existing tunnels were *** volume of surface settlement trough was much smaller than the soil volume moving into the tunnel,due to the heave of the tunnel bottom and the dilation of sand during *** maximum settlement of the segmental lining model was larger than that of the composite lining model as the equivalent bending stiffness of the composite lining model was larger than that of the *** to new tunnel excavation,the soil pressures on different positions of the existing tunnel behaved differently,and the bending movements of the existing tunnels ***,the joint deformation of existing tunnel caused by new tunnel excavation could be classified into three types:(1)translation,(2)rotation,and(3)combination of both.

关键词： centrifuge model test Tunnelling below existing tunnel Settlement Joint deformation

Comparison between responses of reinforced and unreinforced embankments due to road widening

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Journal of Central South University 2009年第5期16卷 857-864页

作者：黄晓明汪浩 School of Transportation Southeast University Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign

The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite element(FE) model. The measured and calculated responses of the embankment and foundation exposed to road widening include the settlement,horizontal displacement,pore water pressure,and shear stresses. It is found that the road widening changed the transverse slope of the original pavement surface resulting from the nonuniform settlements. The maximum horizontal movement is found to be located at the shoulder of the original embankment. Although the difference is small,it is clearly seen that the geosynthetic reinforcement reduces the nonuniform settlements and horizontal movements due to road widening. Thus the reinforcement reduces the potential of pavement cracking and increases the stability of the embankment on soft ground in road widening.

关键词： reinforcement centrifuge model test finite element model embankment road widening

A new method for the stability analysis of geosynthetic-reinforced slopes

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Journal of Mountain Science 2016年第11期13卷 2069-2078页

作者： SONG Fei CHEN Ru-yi MA Li-qiu CAO Geng-ren Institute of Geotechnical Engineering School of Highway EngineeringChang'an UniversityXi'an 710064China Guizhou Electricity Engineering Construction Supervise Company Guiyang 550005China Merchants Chongqing Communications Research and Design Institute Co. Ltd.Chongqing 400067China

This paper is concerned with the stability analysis of reinforced slopes.A new approach based on the limit equilibrium principle is proposed to evaluate the stability of the reinforced *** effect of reinforcement is modeled as an equivalent restoring force acting the bottom of the slice and added into the general limit equilibrium(GLE) *** equations of force and moment equilibrium of the slice are derived and corresponding iterative solution methods are *** new method can satisfy both the force and the moment equilibrium and be applicable to the critical failure surface of arbitrary ***,the results predicted by the proposed method are compared with the calculation examples of other researchers and the centrifuge model test results to validate its correctness and effectiveness.

关键词： Reinforced slope Stability analysis Limit equilibrium General limit equilibrium method centrifuge model test