基于FLAC^(3D)液化场地桩基动力反应振动台试验数值分析方法

Numerical Simulation of Shake Table Test on Dynamic Response of Pile Foundation in Liquefiable Ground Using FLAC^(3D)

液化场地桩基动力响应是岩土地震工程领域重要的研究课题,而研究液化场地桩基动力响应有效的方法包括大型物理模型试验和数值模拟。鉴于此,针对已完成的振动台试验,采用FLAC^(3D)有限差分计算程序,建立了液化场地桩‑土动力相互振动台试验数值模型。在数值模拟中,承台采用实体单元,桩采用桩单元,柱墩采用梁单元,考虑液化效应的饱和砂土采用Finn模型,粘土采用Mohr‑Coulomb模型。模型边界采用自由场边界,采用弹簧‑滑块‑裂缝单元模拟桩‑土界面。通过对比振动台试验结果表明:建立的有限差分数值模型能够再现结构和地基的动力响应,进而验证了数值模型的可靠性。同时,分析了引起数值计算结果与试验结果差异的主要原因。所采用的数值分析方法对类似布置的桩‑土相互作用数值分析提供参考与借鉴。

Dynamic response on pile foundation in the liquefiable ground is an important research topic in the field of geotechnical earthquake engineering.The effective method for exploring dynamic response on pile foundation in liquefiable ground includes large-scale physical model tests and numerical simulations.Based on the finished shake table test,a numerical model of the shake table test on dynamic soil-pile interaction is established using the finite difference program FLAC_(3D) in this study.In the numerical model,the pile cap and the pile are represented by the solid element and the pile element,respectively.The pier is modeled by the beam element.The saturated sand is reproduced by the Finn model to consider the effect of liquefaction and the clay is simulated by the Mohr-Coulomb model.The free field boundary is used as the model boundary condition and the soil-pile interface is characterized by the spring-slider-gap element.The established finite difference numerical model can reproduce the dynamic response of structure and foundation.By comparing with the shake table test results,the simulation results validate the reliability of the numerical model.Meanwhile,the main reasons for the difference between computed and experimental results are presented and analyzed.The analytical method used in this study can provide the general reference for the numerical modeling of similar soil-pile interaction system configurations.