考虑孔隙水压力作用的岩土体弹塑性模型及其有限元实现

岩土工程中孔隙水的作用一直是工程安全稳定分析中不容忽视的问题。基于Viesca提出的考虑饱和孔隙水压力作用的孔隙弹塑性模型，推导其在满足D-P准则的理想弹塑性情况下的具体形式。对于不排水条件，饱水状态下材料强度参数被等效化，使得屈服面的形状发生改变，同时根据最近点投影法确定其在弹塑性计算中的本构积分策略。不排水孔隙水压力对岩土体的塑性响应的影响得以表达，而对结构的稳定性的影响通过基于过应力概念的不平衡力反映出来。基于该模型开发非线性有限元程序PoreTfine，选取非均质边坡降雨入渗下的稳定问题作为算例验证其实用性，边坡随降雨作用的非平衡演化过程得到研究。Skempton系数的增大对连续降雨条件下边坡有弱化作用，对其稳定性不利。

Elastoplastic model for geomaterial considering effect of pore water pressure and its finite elements implementation

The effect of pore water pressure plays an essential role in the analysis of stability and safety of geotechnical engineering. Formulation of a perfect elastoplastic model satisfying D-P criterion is presented based on Viesca’s poroelastoplastic model considering saturated pore pressure. Under the undrained condition, the equivalent strength parameters of geomaterial shall be used, which brings out the change of yield surface shape; and the expression of exact integration algorithms is modified based on the closest point projection method. The effect of undrained pore pressure is thus considered on the elastoplastic response of pore geomaterial; and the evaluation of geotechnical structure is implied by using the unbalanced force inheriting the concept of overstress. A heterogeneous slope suffering rainfall infiltration is simulated by using nonlinear finite element method code, which proved the practicability of the model. The nonequilibrium evaluation of slope stability can be quantified by combining our procedure with the unbalanced force. It is also found that the increment of Skempton’s coefficient weakens the layer of slope suffering sustained rainfall infiltration and threatens its safety.