基于COMSOL的不同库水位条件下土石坝坝坡稳定性分析

An Analysis of the Different Conditions of Reservoir Water Level on the Stability of Earth-rock Dam Slope Based on COMSOL

由库水位变化引起的渗透破坏是造成土石坝失稳的主要原因之一,坝体滑坡极易诱发地质灾害,严重威胁人类生命财产安全。针对库水位上升对土石坝坝体滑坡的影响,以某均质土坝为研究背景,借助COMSOL Multiphysics数值软件研究坝坡临界失稳状态下的塑性区和水平位移变化,基于有限元强度折减法分析正常蓄水位、设计洪水位和校核洪水位3种工况下的坝坡稳定性。结果表明:随着库水位上升,土石坝内部浸润线位置提高,坝体的最大塑性应变和水平位移呈线性增大趋势,且最大值均出现在坝脚位置。坝脚处塑性区随折减系数SRF的增大逐渐向坝顶贯通,坝坡变形行为以剪切滑移为主。3种工况下稳定安全系数FOS分别为1.894、1.855和1.831,坝体稳定性不断降低,但均高于临界最小安全系数。

The seepage failure caused by the change of reservoir water level is one of the main reasons for the instability of the earth-rock dam.Moreover,the landslide would become geological disasters easily,which poses a great threat to human life and property.Aiming at the influence of reservoir water level rise on the landslide of earth-rock dam,this paper uses a homogeneous earth dam as the research back⁃ground.The plastic zone and horizontal displacement changes of the dam slope under the critical instability state are studied by COMSOL Multiphysics.Based on the FEM strength reduction method,the stability of the dam slope under three conditions of normal water level,de⁃sign flood level and check flood level are analyzed.The results show that the phreatic line of earth-rock dam increases with the rise in reservoir water level.The maximum plastic strain and horizontal displacement increase linearly,and the maximum values of the strength reduction factor(SRF),the deformation behavior is mainly a shear slip.The factor of safety(FOS)under three conditions are 1.894,1.855 and 1.831,respectively.The stability of the dam body decreases continuously,but it is higher than the critical minimum factor of safety.