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Generalized response displacement methods for seismic analysis of underground structures with complex cross section

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Earthquake Engineering and Engineering Vibration 2023年第4期22卷 979-993页

作者： xu Zigang Ding Linling Du Xiuli xu chengshun Zhuang Haiyang Jiangxi Key Laboratory of Infrastructure Safety Control in Geotechnical Engineering East China Jiaotong UniversityNanchang 330013China Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

The response displacement method(RDM)is recommended for the seismic analysis of underground structures in the transverse direction for many codes,including bases for design of structures-seismic actions for designing geotechnical works(ISO 23469)and code for seismic design of urban rail transit structures(GB 50909-2014).However,there are some obvious limitations in the application of *** and the shear stress of the soil could be approximately evaluated for the structures having a simple cross section,such as rectangular and circular *** is necessary to propose simplified seismic analysis methods for structures with complex cross *** paper refers to the idea of RDM and proposes three generalized response displacement methods(GRDM).In GRDM1,a part of the soil surrounding a structure is selected to generate a generalized underground structure with a rectangular cross section,and the same analysis model as RDM is applied to analyze the responses of the *** GRDM2,a hollow soil model without a generalized structure is used to compute the equivalent load caused by the relative displacement of the soil,and the soil-structure interaction model is applied to calculate the responses of the *** GRDM3,a continuous soil model is applied to compute the equivalent load caused by the relative displacement and shear stress of the soil,and the soil-structure interaction model is applied to analyze the responses of the structure,which is the same as the model used in *** time-history analysis method(THAM)is used to evaluate the accuracy of the proposed simplified *** show that the error of GRDM1 is about 20%,while the error is only 5%for GRDM2 and *** the three proposed methods,GRDM3 has obvious advantages regarding calculation efficiency and ***,it is recommended to use GRDM3 for the seismic response analysis of underground structures that have conventional simple or complex cross sections.

关键词： underground structures seismic analysis response displacement method equivalent seismic load complex cross section

Experimental study on cyclic deformation properties of saturated Fujian sand at different loading frequencies

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Underground Space 2023年第6期13卷 150-165页

作者： Chong Yue Ke Liang chengshun xu Xiuli Du Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilative(ISD)period)and post-liquefaction(late shearing dilative(LSD)period)deformation properties of saturated Fujian *** secant shear modulus G and damping ratioλin the entire cyclic loading process,and the unloading tangent shear modulus G_(L1)and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude *** test results show that the effect of f on G of saturated Fujian sand in the SC period is not ***,all the G-γ_(a),G_(L1)-γ_(a),and GL2-ca curves in the ISD and LSD periods showed a downward trend with an increase in *** study also proposes a modified method for calculatingλto compensate for the analytical error caused by the non-closure of hysteresis *** with the classical curves that mainly applied in geotechnical engineering,theλfirst increases and then decreases with the increase ofγ***,theλevaluated by the modified method is approximately 10%–15%more than theλevaluated by the traditional method when theλreaches its peak value.

关键词： Sand liquefaction Cyclic loading frequency Hysteresis loop shape Shear modulus Damping ratio

Property estimation of free-field sand in 1-g shaking table tests

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Earthquake Engineering and Engineering Vibration 2022年第3期21卷 591-604页

作者： xu chengshun Jiang Zhiwei Du Xiuli Deng Lijun Li Zheng College of Architecture and Civil Engineering Beijing University of TechnologyBeijing 100124China National Engineering Research Center of Green&Safe Construction Technology in Urban Rail Transit Beijing Urban Construction Design and Development Group Co.Ltd.Beijing 100037China Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Civil and Environmental Engineering University of AlbertaEdmonton T6G2R3Canada UniversitéGustave Eiffel Département GERSLaboratoire Centrifugeuses Géotechniques(CG)Bouguenais 44341France

Experimental data taken from free-field soil in 1-g shaking table tests are valuable for seismic studies on soil-structure *** the available data from medium-to large-scale shaking table tests were not abundant enough to cover a large variety of types and conditions of the *** the study,1-g shaking table tests of a 3-m-height sand column were conducted to provide seismic experimental data about *** sand was directly collected in-situ,with the largest grain diameter being 2 cm and containing a water content of 6.3%.Properties of the sand were estimated under the influence of white noise plus pulse and earthquake motions,including the settlement,the dynamic properties of the sand column,and the three soil layers′shear modulus degradation *** estimated properties were then indirectly verified by means of finite element *** show that the estimated parameters were effective and could be used in numerical modeling to reproduce approximate seismic responses of the sand column.

关键词： 1-g shaking table test seismic sand response dynamic soil properties free-field sand

Seismic stability of jointed rock slopes under obliquely incident earthquake waves

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 527-539页

作者： Huang Jingqi Zhao Mi xu chengshun Du Xiuli Jin Liu Zhao xu School of Civil and Environmental Engineering University of Science and Technology Beijing Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of Technology

Seismic stability of slopes has been traditionally analyzed with vertically propagated earthquake ***,for rock slopes,the earthquake waves might approach the outcrop still with a evidently oblique *** investigate the impact of obliquely incident earthquake excitations,the input method for SV and P waves with arbitrary incident angles is conducted,respectively,by adopting the equivalent nodal force method together with a viscous-spring ***,the input method is introduced within the framework of ABAQUS software and verified by a numerical *** SV and P waves input are considered herein for a 2 D jointed rock *** the jointed rock mass,the jointed material model in ABAQUS software is employed to simulate its behavior as a *** of the study show that the earthquake incident angles have significance on the seismic stability of jointed rock *** larger the incident angle,the greater the risk of slope ***,the stability of the jointed rock slopes also is affected by wave types of earthquakes heavily.P waves induce weaker responses and SV waves are shown to be more critical.

关键词： jointed rock slope seismic stability obliquely incident waves P and SV waves

Critical state uniqueness of dense granular materials using discrete element method in conjunction with flexible membrane boundary

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Particuology 2024年第12期95卷 124-144页

作者： Chenglong Jiang Yajing Liu Lingling Zeng chengshun xu Peng Cao College of Civil Engineering Zhejiang University of TechnologyZhejiang310023China The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing100124China

An explanation of the meso-mechanism of sand granular materials for the uniqueness of critical state is presented by means of the discrete element method(DEM)under flexible boundary loading conditions.A series triaxial drainage shear test(DEM simulations),in conjunction with the flexible boundary technique,of were performed for sand samples subjected to various physical states and with different particle size *** carefully investigating the critical status of the results of the numerical calculation,the macroscopic failure modes and shear band evolution of sand,as well as the velocity vector field due to different initial states,were explored and ***,the evaluation rules and discrepancies between overall void ratios of the specimen and local void ratios within the shear band under the critical state were recorded and *** results proved that a sample with a small void tends to form a shear band,and the rotation of the particles in the non-shear zone is ***,sandy soil with large initial void ratios exhibited limited development of significant shear bands,and the change in void ratios within the shear region and the non-shear area are not ***,the particle-size distribution exerts minimal influence on the evolution rule which the void ratio converges within the shear band and diverges outside the shear region for both multi-stage and single-stage *** void ratio within the shear band and deviator stress ratio tend to exhibit consistently for the same specimen with different initial physical states,thereby distinguishing the critical *** is a significantly higher change in void ratio within the shear band compared to outside of it,yet it remains stable within a relatively similar ***,the invariant of the fabric tensor used to describe the critical state characteristics also demonstrates a high degree of consistency within the shear *** findings stron

关键词： Critical state Flexible membrane boundary Evolution of the void ratio Shear band Fabric tensor

Numerical analysis on seismic performance of underground structures in liquefiable interlayer sites from centrifuge shaking table test

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Earthquake Engineering and Engineering Vibration 2024年第4期23卷 781-798页

作者： Yan Guanyu xu chengshun Zhang Zihong Du Xiuli Wang xuelai Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China China Academy of Railway Sciences Corporation Limited Urban Rail Transit Center of CARSBeijing 100081China

When an underground structure passes through a liquefiable soil layer,the soil liquefaction may pose a significant threat to the structure.A centrifuge shaking table test was performed to research the seismic response of underground structures in liquefiable interlayer sites,and a valid numerical model was obtained through simulation model ***,the calibrated numerical model was used to perform further research on the influence of various distribution characteristics of liquefiable interlayers on the seismic reaction of underground *** key findings are as *** structure faces the most unfavorable condition once a liquefiable layer is located in the middle of the underground *** a liquefiable layer exists in the middle of the structure,the seismic reactions of both the underground structure and model site will increase with the rise of the thickness of the liquefiable *** inter-story drift of the structure in the non-liquefiable site is much smaller than that in the liquefiable interlayer *** inter-story drift of the structure is not only associated with the site displacement and the soil-structure stiffness ratio but also closely associated with the slippage of the soil-structure contact interface under the condition of large deformation of the site.

关键词： centrifuge shaking table test underground structure liquefiable interlayer sites seismic response validation of numerical model

Analysis on kinematic and inertial interaction in liquefiable soil-pile-structure dynamic system

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 601-612页

作者： xu chengshun Liu Hao Dou Pengfei Wang Jinting Chen Su Du Xiuli Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China

The dynamic pile-soil interaction in a liquefied site was investigated by means of numerical simulation and shaking table tests in this *** on the results from the shaking table experiment,the cross-correlation analysis of the soil displacement-pile bending moment and superstructure acceleration-pile bending moment was performed to study the influence of kinematic interaction and inertial interaction on the seismic response of piles.A relatively reasonable and accurate finite difference numerical analysis model of liquefiable soil-pile group-superstructure dynamic system was *** numerical simulation,the understanding of kinematic interaction and inertial interaction in the shaking table test was *** mass,damping and period of the superstructure were selected as variables to carry out parameter analysis to further study the influence of inertial interaction on the pile-structure failure *** results show that the influence of kinematic interaction on the pile was much greater than that of inertial *** mass of the superstructure was the most important parameter of inertial interaction,and dynamic characteristics of the superstructure also had an effect on inertial *** effect of inertial interaction on the part near the pile tip was more significant,indicating that the failure near the pile tip is closely related to inertial interaction.

关键词： shaking table experiments pile-supported structures dynamic response liquefaction lateral constraint instability

Numerical analysis on seismic response and failure mechanism of articulated pile−structure system in a liquefiable site from shaking-table experiments

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1117-1133页

作者： Pengfei DOU Hao LIU chengshun xu Jinting WANG Yilong SUN Xiuli DU Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

This study investigates the seismic response and failure mode of a pile-structure system in a liquefiable site by employing a numerical simulation model combined with the shaking-table results of a soil-pile-structure dynamic *** pile and soil responses obtained from the numerical simulations agreed well with the experimental *** slopes of the dynamic shear-stress-shear-strain hysteretic curves at different positions also exhibited a decreasing trend,indicating that the shear strength of the soil in all parts of the foundation *** peak acceleration of the soil and pile was not clearly amplified in the saturated sand layer but appeared to be amplified in the top *** maximum bending moments appeared in the middle and lower parts of the pile shaft;however,the shear forces at the corresponding positions were not *** can be observed from the deformation mode of the pile-group foundation that a typical bending failure is caused by an excessive bending moment in the middle of the pile shaft if the link between the pile top and cap is articulated,and sufficient attention should be paid to the bending failure in the middle of the pile shaft.

关键词： numerical simulation soil liquefaction pile foundation shaking-table experiment seismic responses failure model

Seismic response comparison and sensitivity analysis of pile foundation in liquefiable and non-liquefiable soils

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 87-104页

作者： Jia Kemin xu chengshun Du Xiuli Cui Chunyi Dou Pengfei Song Jia Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of Technology Beijing 100124China Transportation Engineering College Dalian Maritime University Dalian 116026China North China University of Technology School of Civil Engineering Beijing 100144China

Case history investigations have shown that pile foundations are more critically damaged in liquefiable soils than non-liquefiable *** study examines the differences in seismic response of pile foundations in liquefiable and non-liquefiable soils and their sensitivity to numerical model parameters.A two-dimensional finite element(FE)model is developed to simulate the experiment of a single pile foundation centrifuge in liquefiable soil subjected to earthquake motions and is validated against real-world test *** differences in soil-pile seismic response of liquefiable and non-liquefiable soils are ***,the first-order second-moment method(FOSM)is used for sensitivity analysis of the seismic *** results show significant differences in seismic response for a soil-pile system between liquefiable and non-liquefiable *** seismic responses are found to be significantly larger in liquefiable soil than in non-liquefiable ***,the pile bending moment was mainly affected by the kinematic effect in liquefiable soil,while the inertial effect was more significant in non-liquefiable *** controlling parameters of seismic response were PGA,soil density,and friction angle in liquefiable soil,while the pile bending moment was mainly controlled by PGA,the friction angle of soil,and shear modulus of loose sand in non-liquefiable soil.

关键词： liquefiable non-liquefiable finite element analysis pile foundation seismic response sensitivity analysis