路堤式加筋土挡墙三维数值模拟

Three dimensional Numerical Simulation of a Reinforced Soil Embankment/Wall

摘要:

采用3维有限元程序Z_Soil对某软土地基上路堤式加筋土挡墙建立考虑流固耦合的3维数值模型，分析其地基沉降、墙面变形、筋材应变分布以及稳定性，并与实测值和2维有限元Plaxis分析结果进行比较.分析结果表明:采用等效竖向渗透系数模拟塑料排水板处理地基是合理的，计算的地基沉降、墙面变形随时间变化历程与实测结果吻合较好；3维有限元在筋、土及其界面单元模拟上要比2维有限元精细，能较好地模拟墙面“鼓肚”现象；3维有限元计算的筋材应变随地基变形而增大，且挡墙底部筋材应变最大，计算结果符合地基变形情况下筋材应变变化规律；3维有限元模拟的挡墙在平面呈弧形扩展的滑裂面形状和位置与现场试验观测结果一致，其较2维有限元在模拟本问题加筋土挡墙上要更加合理.

Abstract:

A three dimensional seepage coupling finite element modeling using Z_Soil3D was performed on a reinforced soil embankment/wall(RSW) on soft clay. The settlement，horizontal displacement，geogrid strain, and stability of the RSW were analyzed and compared with the measurements as well as the calculation results from 2D finite element program Plaxis2D. The results show that it’s reasonable to use the equivalent vertical conductive coefficient to simulate the foundation treated with prefabricated vertical drains. The calculated foundation settlement and RSW deformation varying with time agree well with the measurements. Compared with 2D FEM, 3D FEM can more deliberately simulate the elements of geosynthetics, soil and their interface and consequently well capture the bulging of RSW facing during step loading. The calculated strain of each geogrid increases with an increase of foundation settlement and the strain of base reinforcement reaches the maximum value of those all, which agrees with the finding of variation of geosynthetics strain with foundation settlement. The simulated slip surface which exhibits arc in plan view is in consistence with the observed failure mode of the RSW. Therefore, 3D FEM is more capable to capture the behavior of this RSW on soft clay.