考虑地震动地形效应的边坡破坏概率--以金沙江下游新市镇附近边坡为例

Seismic slope failure probability considering the topography effects——Case of slopes near Xinshi town alongside the lower Jinsha river

边坡在地震作用下的破坏概率是地震边坡危险性评价的参数之一。在区域范围内计算地震边坡破坏概率一般采用实际地震滑坡和Newmark永久位移拟合得到的破坏概率公式进行计算。计算中所需的地震动峰值加速度数值大小受不规则地形的影响较大。为了较准确计算出区域地震边坡的破坏概率,本文利用公式分别计算了地震动峰值加速度地形效应系数和地震边坡滑坡概率,实现了地震动峰值加速度及滑坡概率的连续分布。在计算地表30 m平均剪切波速时,利用回归分析方法得出了Vs30与地形梯度G的连续性关系。这些方法充分考虑了地形在地震动峰值加速度中所起的作用,能够实现地震边坡破坏概率计算结果的连续性,如实反映了地震边坡破坏概率的实际状况,为更准确评价地震边坡滑坡危险性提供了新的思路。

The failure probability of slope under earthquake is one of the parameters of seismic slope risk assessment. The failure probability formulas obtained by combining the actual seismic landslide and the Newmark permanent displacement are selected to calculated the failure probability generally. The peak ground acceleration required in the calculation is greatly influenced by the irregular topography. In order to calculate the failure probability of regional seismic slope more accurately, this study calculates the topography effect coefficients and the failure probability separately using formulas and achieves the continuous topography effect coefficients and failure probability. Continuous relations between V30 and topography gradient G are acquired by regression analysis for calculating the average shear wave 30 m below the earth surface. These methods take full account of the role of the terrain played in the peak acceleration of ground motion and the continuity of the calculated results of the seismic slope failure probability is realized. By means of this method, the actual condition of the slope failure probability is reflected, which provides a new idea for more accurate seismic slope risk assessment.