Upper bound solution for active thrust of nonhomogeneous cohesive soil considering effects of intermediate principal stress

考虑中主应力影响的非均质土体主动土压力上限解

Considering the variation of cohesion along the depth,the upper bound solution of active earth pressure for a rough inclined wall with sloped backfill is formulated based on a log-spiral failure mechanism.For a more accurate prediction,the influence of intermediate principal stress is taken into consideration using the unified strength theory.Converting the search for the active pressure to an optimization problem,the most critical failure surface can be located by a natural selection-based gravitational search algorithm(GSA).The proposed method is validated compared with existing methods for noncohesive and cohesive cases and proved to be more accordance with the limit equilibrium solution.The influences of the variation of soil cohesion and intermediate principal stress on active earth pressure coefficient are then fully studied.It can be concluded that both the variations of soil cohesion and intermediate principal stress have a significant influence on the active earth pressure coefficient.

本文基于对数螺旋线破坏机构,同时考虑黏聚力随深度变化,推导了墙背倾斜及粗糙情况下的挡土墙主动土压力计算公式。为了更贴近实际情况,考虑了基于统一强度理论土体中主应力对土压力的影响。为了准确计算土压力,把主动土压力计算转化为优化问题进行求解,并引入万有引力算法搜索最危险滑裂面。通过与已有的均质和非均质土层中土压力研究结果对比,发现本文提出的方法更接近传统极限平衡解。最后,深入探讨了土层非均匀性及中主应力对主动土压力的影响,发现土层非均匀性及中主应力对主动土压力有显著影响。