基于PM4Sand塑性模型的土体液化侧移计算分析

Calculation and Analysis of Soil Liquefaction Lateral Displacement Based on PM4Sand Plastic Model

采用PM4Sand塑性模型预测土体因地震而液化引起的侧移量。利用有限差分程序,引入依据临界状态理论、由应力控制的砂土屈服面塑性模型模拟可液化土,对既有液化场地进行分析,预测由地震引起的场地液化侧移。根据既有场地的地质勘察资料和相关地震波,获取场地输入地震波和可液化土的动力触探值,确定可液化土的本构模型参数,再根据摩尔-库伦破坏准则设置非液化土的相关参数。监测场地自由面的液化侧移,记录可液化土的孔隙水压力,并将地表加速度时程与初始输入地震波加以对比。结果表明:在输入地震波作用下,场地发生液化且产生侧移,所得预测值较实测值大;场地对地震输入有一定的放大作用; PM4Sand砂土模型适用于实际工程的液化侧移预测。

PM4Sand plastic model was used to predict the lateral displacement caused by liquefaction due to earthquake.By using finite difference program,the plasticity model of sand yield surface controlled by stress was introduced to simulate liquef iable soil based on critical state theory,the existing liquefaction field was analyzed and the field liquefaction lateral displacement caused by the earthquake was predicted.According to the geological survey data of the existing field and related seismic waves,the field input seismic waves and the dynamic penetration values of liquef iable soil were obtained,the parameters of constitutive model for liquef iable soil were determined,and the relevant parameters of non-liquefiable soil were set according to Mohr-Coulomb failure criterion.The liquefaction lateral displacement of the field free surface was monitored,the pore water pressure of liquefiable soil was recorded,and the time history of ground acceleration was compared with the initial input seismic wave.The results show that under the action of input seismic waves,both the field liquefaction and lateral displacement happen,the predicted value is larger than the measured value,and the field has a certain amplif ication effect on seismic input.PM4Sand plastic model is suitable for prediction of liquefaction lateral displacement in practical engineering.