剪切波作用下桩筏基础的动力响应研究

摘要

A numerical study on the kinematic, responses of pile-raft foundation subjected to vertically propagating S-wave seismic excitation was presented. The dynamic soil-pile-raft interaction was modeled by using the thin layered element method and the finite element method. The effective input motions of pile-raft foundation were expressed with dimensionless horizontal response factor IH and rocking response factor IR, which were the ratios of raft motions to free-field soil surface motion. The horizontal and rocking response factors of pile-raft foundation were compared with those of pile group and raft foundation. The effects of pile lengths, spacings and rigidities on kinematic response factors of pile-raft foundation were also studied. The results have shown that the neglect of the effect of the raft can result in too small an evaluation of the kinematic response factors of pile-raft foundation when the pile spacing is relatively large.%对垂直传播的剪切波作用下桩筏基础的动力响应进行了数值分析.采用薄层元素法和有限单元法建立了土、桩和筏板三者之间的相互作用分析模型,着重分析了桩筏基础的有效输入地动(即反映了筏板响应与自由场地面运动大小关系的水平和摇摆动力响应系数).对桩筏基础和群桩、筏板基础的水平和摇摆动力响应系数进行了比较,并讨论了桩的距径比、桩的长径比以及桩土弹性模量比对桩筏基础的动力响应系数的影响.结果表明,当桩的距径比较大时,忽略筏板的影响会导致对桩筏基础的动力响应系数的过小评价.