车辆荷载下路基挡土结构失稳机理数值模拟

随着公路交通流量增加及超载车辆增多，路基挡土结构变形或失稳现象时有发生。结合山东省荷泽市人民路公铁立交桥加筋土挡土墙失稳问题，在分析车辆动载效应的基础上采用FLAC有限差分方法对车辆动荷载下路基挡土结构失稳机理和变形破坏过程进行详细分析，认为路面动载荷对墙体的作用过程与时间及空间位置有关，筋体变形叠加及破坏导致墙体失稳，挡土结构变形破坏内在机理包括墙体上部的劈裂张开和中下部的共轭剪切体水平方向挤出。同时，对不同高度挡土结构失稳形式、非对称动载荷条件下挡土结构的失稳特点进行了全面分析。基于动载荷的特点及挡土墙墙体和筋体的缺陷，认为失稳加筋土挡土墙的加固必须同时考虑控制变形破坏和增加土体强度的措施，实现内外结合、点面兼顾的综合治理。所得结论为类似失稳路基挡土结构加固方案和综合治理措施的确立奠定科学基础。

Numerical simulation of failure mechanism of subgrade retaining structure under vehicle load

With the increase of the traffic and the over-load vehicles,the failure of the subgrade retaining structure is always being reported.For a failure earth retaining wall of the Renminglu grade separation bridge in Hezhe City of Shangdong Province,the dynamic effect of the vehicles has been firstly analyzed.Based on the finite difference method of FLAC,the failure mechanism and the failure development under the dynamic vehicles load have been researched.It is concluded that the effect of vehicles dynamic load is a time-spatial process,and the displacement of the strip net induces the wall failure.The failure mechanism of the retaining structure can be shown as the tensile failure in the upper part and the shear failure in the lower and medium parts.At the same time,a comparing study on the height of the retaining wall and non-symmetric dynamic load has been done.The result indicates that in the reinforcement of the failure retaining wall both controlling the deformation and increasing the soil strength are important for a comprehensive engineering project.The conclusion of this paper will be a useful reference for the analogous failure of earth retaining structures.