库水位变化和降雨作用下三门洞滑坡流固耦合分析

Fluid-solid coupling analysis for Sanmendong landslide under the co-action of rainfall and water level fluctuation

目前对三门洞滑坡的已有研究都重点关注稳定系数和变形特征,缺乏对孔隙水压力及应力演化特征的系统性研究。采用Abaqus建立滑坡的三维计算模型,推导库水位变化和降雨入渗的耦合边界条件,提出基于莫尔-库伦和最大拉应力准则相结合的复合准则,模拟滑坡在库水位变化和降雨共同作用下的变形演化过程。系统探讨了滑坡的孔隙水压力分布、位移场、应力场和塑性区分布特征,并综合数值模拟结果分析了库水位变化和降雨入渗条件下的边坡稳定性问题。结果表明:在强降雨和库水位缓慢下降综合作用下,三门洞滑坡在滑坡中后部和前缘分别出现局部的张拉和剪切破坏,滑体内渗流场发生较大变化,导致滑体内孔隙水压力、应力、位移和等效塑性应变整体增大,但并未出现塑性破坏区,边坡整体处于稳定状态。

At present,the researches on Sanmendong landslide mainly focus on its stability factor and deformation characteristics,lacking systematic research on the characteristics of pore water pressure and stress.A three dimensional computational model of the landslide based on Abaqus,the coupled boundary conditions of water level fluctuation and rainfall infiltration and the combined criteria of Mohr-Coulomb and Maximum Tensile Stress criteria are established.Then,the deformation process of landslide under the co-action of water level fluctuation and rainfall is simulated by using Abaqus,and the pore water pressure distribution,displacement field,stress field and plastic zone in the slope are obtained as well.Finally,the slope stability under the co-action of water level fluctuation and rainfall is derived by the numerical simulation results.The results show that under the co-action of slowly water-level drawn down and intensive rainfall,local tension failure occurs in the middle-rear part of the slope and local shear failure in the leading edge of the landslide.The seepage field in the landslide changes greatly,resulting in the increase of the pore water pressure,stress,displacement and equivalent plastic strain,but without plastic failure zone is found,which indicates that the slope is stable.