基于静动力有限元的边坡抗震稳定分析方法

Slope aseismic stability analysis method based on static and dynamic finite elements

由人工截断边界输入地震波,通过时程积分法确定地震荷载作用下边坡的应力和变形,在人工截断边界上采用黏-弹性人工边界条件模拟地基辐射阻尼的影响。采用有限元强度折减法求解边坡稳定安全系数,以塑性区贯通时刻特征点的位移突变作为边坡失稳的评判标准。非线性有限元和黏-弹性人工边界条件结合运用,建立了基于静动力有限元的边坡抗震稳定分析方法。该方法在稳定安全系数的定义上和传统的刚体极限平衡法是一致的。以十里铺水电站为工程实例,分析了库区边坡的抗震稳定性,得出了边坡动力位移时程和动力稳定安全系数,计算结果合理评价了实际工程在地震荷载下的稳定性。

The seismic wave is input through artificial truncated boundaries, and the stress and deformation of the slope induced by seismic loading are determined by time-integration method. The effect of foundation radiation damping is simulated by adopting viscoelastic artificial boundaries condition on artificial truncated boundaries. Safety factor of slope stability is solved by finite elements strength reduction method. The displacement saltation of feature points when the connection of plastic zone occurs is considered as an instability criterion of the slope. The slope aseismic stability analysis method based on static and dynamic finite elements is put forward through combining the dynamic finite element method with the viscoelastic artificial boundaries conditions. On the definition of safety factor, the method is consistent with the traditional grid limit equilibrium method. Finally, taking Shilipu Hydropower Station for example, the slope dynamic stability of the reservoir slope is analyzed; and the time history of the slope dynamic displacements and the safety factor of dynamic stability are obtained. The calculation results agree very well with geological survey and are close to the actual situation, so as to indicate that the method can be used to evaluate dynamic stability of the practical engineering.