挡土墙主动土压力塑性临界深度的解析解

墙后塑性区的临界深度问题一直没有得到很好解决，传统计算公式仅适用于一些特殊情况。基于极限平衡理论，视墙后填土为服从Mohr-Coulomb屈服准则的理想弹塑性材料，假定塑性区的一族滑移线为直线即平面滑裂面，提出弹性覆盖层取代传统的张拉裂缝，建立了较为完善的滑楔分析模型，采用极限平衡法推导了在一般情况下的塑性临界压力、临界深度以及塑性区可能最大深度的解析解。计算结果表明，塑性临界深度的解析解与目前文献采用迭代计算的结果完全一致，传统计算公式是该解析解的一个特例。

Analytical solution of plastic critical depth for active earth pressure on retaining wall

The problem of critical depth for plastic zone behind the retaining wall has not yet been solved well. The conventional calculation formula is only applicable for some special cases. This paper is based on the limit equilibrium theory, in which the backfill is treated as a perfectly elastoplastic material following the Mohr-Coulomb yield criterion; and it is assumed that a family of slip lines in the plastic zone are straight lines, i.e. the plane slip surfaces. The elastic overburden is put forward to replace the conventional tension crack; and a more reasonable slip wedge analysis model is established. The analytical solutions of the plastic critical pressure and critical depth and the possible maximum depth in plastic zone for active earth pressure on retaining wall in general case are deduced using limit equilibrium method. The calculation results show that the analytical solution of the plastic critical depth is identical with the result by iterative calculation in existing literatures and the conventional calculation formula is a special case of this analytical solution.