考虑PSSI的桩柱式桥墩震后残余位移分析  

Analysis on the Residual Displacement of Extended Pile-Shafts Considering Pile-Soil-Structure Interaction(PSSI) After Earthquakes

作　　者：孙治国 张振涛 伍隋文 王东升 SUN Zhiguo;ZHANG Zhentao;WU Suiwen;WANG Dongsheng(School of Civil Engineering,Institute of Disaster Prevention,Beijing 101601,China;Key Laboratory of Building Collapse Mechanism and Disaster Prevention,China Earthquake Administration,Beijing 101601,China;Department of Civil and Environmental Engineering,University of Nevada,Reno 89557,USA;School of Civil and Transportation Engineering,Hebei University of Technology,Tianjin 300401,China)

机构地区：[1]防灾科技学院土木工程学院,北京101601 [2]中国地震局建筑物破坏机理与防御重点实验室,北京101601 [3]内华达大学里诺分校土木与环境工程系,美国里诺89557 [4]河北工业大学土木与交通学院,天津300401

出　　处：《应用基础与工程科学学报》2022年第3期684-694,共11页Journal of Basic Science and Engineering

基　　金：河北省重点研发计划项目(19275417D);国家自然科学基金项目(51678150,51978167);防灾科技学院研究生科技创新基金项目(ZY20190301)。

摘　　要：为研究钢筋混凝土桥墩在强震下的残余变形机理,建立了考虑桩-土-结构相互作用(pile-soil-structure interaction, PSSI)的桩柱式桥墩抗震数值分析模型,考虑了桥墩、桩身以及桩-土相互作用等非线性行为.首先,基于单桩拟静力试验结果验证了建模方法的准确性,然后通过与墩底固结模型的对比,分析了近断层地震动下PSSI对桩柱式桥墩墩顶残余位移的影响.结合结构自振周期,桩身残余位移、曲率延性系数,土体非线性反应等结果,对墩顶残余变形的机理进行了讨论.结果表明:考虑PSSI的桩柱式桥墩自振周期为墩底固结模型的2.0~2.2倍,PSSI显著增加了墩顶的最大位移和残余位移.随着砂土相对密实度减少,结构自振周期、墩顶最大位移和残余位移均呈增大的趋势.桩身的残余变形主要集中于桩顶4倍桩径深度范围内,且随着砂土相对密实度增加,桩身残余变形深度减少.桩身塑性变形集中于地表下1.3~5.3倍桩径范围内,且随着砂土相对密实度增加,桩身塑性区范围减少,桩身截面最大曲率增大.To study the mechanism of residual deformation of reinforced concrete bridge piers under strong earthquakes, a nonlinear numerical model for seismic behavior of extended pile-shaft considering pile-soil-structure interaction(PSSI) was developed.In this model, the nonlinear behavior of the bridge pier, pile and pile-soil interaction were considered.To begin with, the modeling techniques were validated against quasi-static test results for single-pile from other researchers.In addition, the validated model was then employed to study the influence of the PSSI on the residual displacement of extended pile-shaft.Nonlinear response history analysis was performed on the models with and without considering the PSSI under a suite of near-fault ground motions.The mechanism of residual deformation of pier top was discussed in terms of the natural vibration period, the residual displacement and curvature ductility of the pile, and the nonlinear behavior of the soil.It is found that the natural vibration periods of the models for the extended pile-shaft are 2.0~2.2 times of the model for the fix-base pier.The PSSI would substantially increase the maximum and residual displacement of the pier top.In addition, with the decrease of the relative density of sand, the natural vibration period, the maximum and residual displacement of the pier top would increase.Furthermore, the residual deformation of the pile would concentrate at the top region within a depth of about 4 times of the pile diameter, and the depth of this region would decrease with the increase of the relative density of sand.The plastic deformation of the pile would concentrate at a region under the ground with a depth between 1.5~5.3 times of the pile diameter.With the increase of the relative density of sand, the plastic deformation region would decrease but the maximum curvature of the pile would increase.

关 键 词：桥梁抗震 桥墩 残余位移 桩-土-结构相互作用 数值分析 p-y弹簧单元 近断层地震动 

分 类 号：U443.2[建筑科学—桥梁与隧道工程] TU470.3[交通运输工程—道路与铁道工程]