汶川地震岩质边坡崩塌机理分析

Analysis of Collapsing Mechanism of Rock Slope in Wenchuan Earthquake

为研究岩质边坡的地震崩塌机理,对汶川地震广岳铁路沿线岩质边坡进行震害调查,发现与拟静力分析的滑移假设不同,地震作用下块体崩塌具有抛射特征。通过对楔形块体岩质边坡模型进行有限差分动力数值计算,发现水平地震动作用下块体顶部会产生0.9倍水平向峰值加速度的垂直向峰值加速度,块体内部的水平向峰值加速度约为相同高度完好岩体水平向峰值加速度的2倍;块体在强地震作用下产生的是斜向下抛射运动而非平抛运动,初始速度矢量与水平面的夹角约为41.6°。研究初步揭示了岩质边坡在地震作用下的崩塌机理,为深入揭示块体的地震动响应规律奠定了基础。

To research the collapsing mechanism of rock slope under earthquake,field investigation on damages of rock slopes of Guanghan to Yuejiashan Railway in Wenchuan seismic area is made,and it is found that different from sliding hypothesis,it is characerized by throwing of rock blocks collapsed under earthquake.Finite-difference dynamic numerical calculation is made to wedged rock mass,and it is found that vertical peak ground acceleration（PGA） at top of rock block is 0.9 times as large as that of horizontal peak ground acceleration,and PGA in rock block is about 1 times larger than that in wholesome rock mass.Rock block is ejected with a downward included throwing angle about 41.6° under strong earthquake,but not threw horizontally.Collapsing mechanism of rock slope under earthquake is discovered prelimilarily,and substantial basis is made for further research on seismic response of rock mass.