地震和降雨作用下的填土边坡室内模型试验研究

Indoor Model Test Study on Fill Slope under Earthquake and Rainfull

为了研究地震和降雨共同作用对边坡稳定性影响,进行了先地震后降雨的物理模型试验,并借助模型试验的结果分析了地震和降雨作用下边坡的动态响应和变形破坏机制。试验结果表明,通过PGA放大系数可知,不同类型的地震波作用下,监测点的加速度响应呈现放大现象,且都是坡顶最强,坡中次之,坡脚最弱。而X-土压力则表现为坡底的响应最弱,随着高度的增大逐渐增大,在坡中某位置达到最大值后开始减小。其沿水平向的响应趋势为:由坡内向坡外水平移动响应呈现逐渐减小的趋势。在震后降雨工况下,对边坡的降雨入渗速率和破坏模式进行了分析。通过监测数据可知,坡顶和坡面的入渗速率总体上呈现减小的趋势,32 min之前坡顶下方的平均入渗速率要大于坡面,32 min之后则是坡面下方的平均入渗速率大于坡顶。此次模型试验的破坏模式为浅层流滑型破坏,破坏过程由片蚀向沟蚀发展,最终形成了贯穿坡面的冲蚀沟。

In order to study the effect of earthquake and rainfall on the slope stability, the physical model test of rainfall after earthquake is carried out, and the dynamic response and deformation mechanism of the slope under the action of earthquake and rainfall are analyzed with the help of the model test. The test results show that the acceleration response of monitoring points is magnified under the action of different types of seismic waves by PGA magnification factor, and all of them are the strongest at the top of the slope, second in the middle of the slope, and the weakest at the foot of the slope. The X-dynamic soil pressure shows the weakest response at the bottom of the slope, which increases with the increase of height, and then decreases after reaching the maximum value at a certain position in the slope. The response trend along the horizontal direction is that the horizontal movement response decreases gradually from the interior of the slope to the outside of the slope. Under the condition of rainfall after earthquake, the rainfall infiltration rate and failure mode of slope are analyzed. From the monitoring data, the infiltration rate of the top and surface of the slope shows a decreasing trend on the whole. Before 32 min, the average infiltration rate under slope top is larger than that under slope surface. After 32 min , the average infiltration rate under slope surface is larger than that under slope top. The failure mode of the model test is shallow fluid-slip failure, the failure process develops from sheet erosion to trench erosion, and finally the erosion trench is formed through the slope surface.