基于非线性破坏准则的挡土墙被动土压力上限分析

传统的挡土墙土压力计算基于Mohr-Coulomb线性破坏准则,但大量试验数据表明,土体破坏时最大主应力和最小主应力的关系是非线性的。为此,基于Mohr-Coulomb非线性破坏准则,将挡土墙后填土划分为多个刚性滑块组成的破坏机构,根据极限分析中的上限理论建立容许的速度场。根据岩土实际应力情况,不同边界采用不同的切线强度计算参数,提出一种"多切线法",推导得出挡土墙被动土压力的解析表达式,通过大型数学规划理论优化得到最优上限解。计算结果表明:当非线性破坏准则变为线性破坏准则时,结果与前人成果一致;非线性参数m、超载q、初始黏结力C0对被动土压力有重要影响;与单切线法相比,采用多切线法理论上更加严密,计算结果更接近真实值,具有较高的实用价值。

Upper Bound Solutions for Passive Earth Pressure of Retaining Wall Basedon Nonlinear Failure Criterion

Conventional calculations of earth pressure for retaining walls are made in terms of the linearMohr-Coulomb(MC) failure criterion.However,a substantial amount of experimental data shows that the relationship between the first principal stress and the third principal stress is nonlinear when soil is broken.Therefore,based on the Mohr-Coulomb nonlinear failure criterion and the multi-wedge translation failure mechanism,considering the effect of normal stress distribution on the cohesion and the internal friction angle,giving different boundary surfaces to different cohesion and internal friction angle,by the optimization theory,the multi-tangential technique is used to deduce the passive earth pressures of retaining walls.The minimum solution is obtained by optimization.From the calculation results,it can be seen that if the nonlinear Mohr-Coulomb yield criterion turns into the linear Mohr-Coulomb yield criterion,then the solutions presented in this paper agree well with the chen and soubra research conclusions,and the nonlinear parameter,overloading and initial cohesion have significant effects on the passive earth pressures.Compared with the single-tangential technique method,the multi-tangential technique method is more rigorous in theory and is closer to real values in practice;so it is of high practical applicability.