考虑卸荷及变形影响的基坑挡墙土压力

基于现行基坑支护结构设计采用的弹性支点法对墙后主动区土压力采用经典的朗肯土压力理论,没有考虑墙体变形对墙后土压力的影响,墙前被动区也只考虑了位移的线性影响,根据基坑挡墙前后土体的应变状态模式假定,采用不同卸荷应力路径试验得到土体应力应变关系,建立考虑卸荷及变形影响的非极限主动、被动土压力计算公式.然后,对公式参数的取值进行讨论.研究结果表明:该计算公式不仅考虑了卸荷应力路径,而且能够反映变形对土压力的非线性影响.

Earth pressure applied in retaining wall of deep foundation pit considering influence of unloading and deformation

There are some inadequacies in the current elastic fulcrum method about the design of retaining wall of deep foundation pit,and the classical earth pressure theory is adopted,but the influence of the deformation of retaining wall on earth pressure is neglected and linear infuence is assumed in front of retaining wall,based on the assumption for stain state mode of soil in both sides of retaining wall,the calculation formula for non-limit state active earth pressure and passive earth pressure considering unloading and deformation of retaining wall was presented,in which the stress strain relationship obtained from different unloading stress path laboratory tests was adopted.And the methods for obtaining parameters were discussed.The results show that the different unloading stress paths are considered in this formula,and it can well reflect the nonlinear influence of deformation to lateral earth pressure,which can be confirmed by a simple example.