岩石边坡动力稳定安全系数的块体单元法分析

ANALYSIS OF DYNAMIC FACTOR OF SAFETY OF ROCK SLOPE WITH BLOCK ELEMENT METHOD

将动力分析的块体单元法应用于岩石边坡地震稳定时程分析。将黏弹性人工边界条件的思想与块体单元理论相结合,建立块体系统的人工边界条件,用以模拟地基的弹性恢复能力和地基对散射波能量的吸收,从而消除波动在计算区域边界上的反射。黏弹性边界具有稳定性好,易于与计算程序结合的优点。通过动力计算所得的块体加速度计算块体的惯性力,并由此判断块体可能的滑动模式,进而根据滑动模式将惯性力分解为块体滑动力和垂直于滑动方向的作用力,由此作用力计算块体的抗滑力。块体抗滑稳定安全系数即为抗滑力与滑动力之比,从而可以得到地震过程中块体稳定安全系数时程曲线。小湾水电站进水口边坡算例体现了该方法的工程应用能力。

Block element method(BEM) for dynamic analysis is developed and applied to historical analysis of seismic stability of rock slope. Combining the idea of viscoelastic boundary with the theory of BEM,the artificial boundary condition of BEM is formulated,which can eliminate the reflection of the seismic waves on the boundaries of the computational domain. Viscoelastic boundary has the merits of numerical stability and convenience to integrate with computational program. The inertial force of rock block is firstly computed by its acceleration obtained by dynamic analysis,then is decomposed according to supposed sliding mode into sliding force and force perpendicular to the supposed sliding direction,which is used for calculating resistance force. The factor of safety against sliding is defined by the ratio of the resistance force to the sliding force. When the seismic process finishes,the time-history curve of factor of safety against sliding of rock block can be obtained. The application of the intake slope of Xiaowan Hydropower Station demonstrates the capacity of this method.