基于FEM的面板堆石坝坝坡稳定及可靠度分析

Reliability Method Applied to Slope Support Design

针对刚体极限平衡法不能考虑材料本构关系和复杂荷载条件的问题,提出了一种基于FEM的面板堆石坝坝坡稳定及可靠度分析方法,该方法根据平面非线性有限元法计算得到的滑面应力分量建立坝坡稳定安全系数计算公式,进一步根据安全系数的均值和标准差计算坝坡稳定的可靠度。对某面板堆石坝进行了分析,基于FEM的安全系数与可靠度计算结果规律一致;坝坡及深层稳定的安全系数接近,但可靠度相差较大;相同工况下基于FEM计算的安全系数均大于简化毕肖普法。研究表明,刚体极限平衡法不能反映面板堆石坝上游水压力对提高下游坝坡稳定性的影响,计算结果偏保守;当不同土料强度参数的变异性差异较大时,尽管安全系数接近,可靠性却并不对等。

Limit equilibrium method can not consider the material constitutive relations and complex loading conditions, a FEM-based slope stability and reliability analysis method for concrete faced rock-fill dams was proposed, the safety factor of slope stability is es- tablished based on the stresses at the slip surface gained by plane nonlinear finite element method, and the slope reliability is calculated based on the mean and standard deviation of the safety factors. A real dam was analyzed, the tendency of safety factors and reliability indices of dam slope from the FEM-based method was similar, the safety factor affecting the dam slope and foundation was close to each other, but reliability indices were quite different, the safety factors calculated by the FEM-based method were greater than the simplified Bishop＇s method. It can be concluded that limit equilibrium method does not involve the effect of upstream hydraulic pressure upon the stability of downstream slope, so the results are conservative, because of the randomness of soil strength parameters, the safety factor is close, but not on the reliability.