基于PL-Finn模型的饱和砂土液化数值分析

Numerical analysis of saturated sand liquefaction based on PL-Finn model

为研究地震作用下沉箱式码头的砂土液化特征,基于包含动孔压上升的PL-Finn模型,结合现场实测和大型有限差分软件FLAC^(3D),采用完全非线性的动力分析方法,同时考虑地震动载荷与渗流的耦合作用,对置换砂和回填砂土的超孔压比进行了分析,并将现场实测结果与有限差分模拟结果进行对比分析.结果表明:码头最大水平残余位移为3.47 m,最大残余沉降为1.86 m;回填砂土在地震动载荷施加第6~9 s时已经发生了液化,且超孔压比接近1;置换砂土基本没有发生液化现象,残余超孔压比稳定在0.25~0.30;模拟计算所得的沉箱沉降量比现场实测值低7%,即有限差分模拟结果与实测数据基本吻合,认为采用FLAC^(3D)有限差分方法可以很好地模拟地震砂土液化过程.

In order to study soil liquefaction characteristics of caisson wharf on seismic load condition, based on PL - Finn model containing dynamic pore pressure increase, this paper combined with the field measurement and large finite difference software FLAC3D, and analyzed pore pressure ratio of the replaced sand and land sand by means of the fully nonlinear dynamic analysis method, simultaneously in consideration of coupling effect of seismic load and seepage, and the measured results and the finite difference simulation results are comparatively analyzed. Results show that the terminal peak residual displacement of wharf is 3.47 m and that the maximum residual subsidence is 1.86 m; liquefaction of land sand have taken place 6-9 seconds after the seismic load is applied and super pore pressure ratio is close to 1; liquefaction of few sandy soil occurs and the residual super pore pressure ratio is around 0.25-0.30; The difference between settlement of in-situ test and that of simulation calculation is about 7%, which contributes to drawing a conclusion that the result of finite difference method is basically equivalent to the in-situ data and that finite difference software FLAC3D can be a good simulation of sand liquefaction process.