基于降雨渗流条件下的土质边坡稳定性时间特征研究

Study on Stability Time Characteristics of Soil Slope under Rainfall Seepage Condition

在降雨渗流条件下,边坡的稳定性会受到很大的影响,安全系数通常是在降雨停止后的一段时间出现最低值,安全系数研究对于监测预警和防灾减灾具有重要的意义。为了探究这个问题,从工程地质条件的角度出发,把土质边坡的土体性质和形态特征作为重要的考虑因素,再基于饱和-非饱和渗流理论和采用修改的Mohr-Coulomb破坏准则来计算非饱和边坡的抗剪强度。研究结果表明:①多数情况下,渗流速度快的土体降雨停止后,达到稳定性最低点的时间要早一些,恢复到原来的稳定状态也要更快一些,所以也要充分把握岩土体的性质。②陡坎对于降雨渗流情况下土质边坡稳定性最低点时间滞后起着重要的作用,它主要是影响滑坡前缘渗流截面的宽度。③一般情况下,滑移面越深,降雨渗流情况下土质边坡稳定性最低点的时间滞后越明显,反之则越不明显。

Under the condition of rainfall seepage,the stability of slope is often greatly affected,and the safety coefficient is usually the lowest value after the stop of rainfall,which is of great significance for the detection of early warning and disaster prevention and reduction.To explore this question,so this article from the perspective of the engineering geological conditions,the soil slope soil properties and morphological characteristics as an important consideration,then based on the saturated-unsaturated seepage theory and the modified Mohr-Coulomb failure criterion to calculate the shear strength of unsaturated slope,combining with the instance,the results show that:①The majority of cases,seepage flow speed of the soil after the rain stopped,achieve stability nadir some time earlier,restore to the original steady state also want faster,so also should fully grasp the nature of rock and soil mass.②Steep cantilever plays an important role in the bottom time lag of stability of soil slope under the condition of rainfall seepage.It mainly affects the width of seepage section of the front edge of landslide.③In general,the deeper the slip surface,the more obvious the time lag at the lowest point of stability of soil slope under the condition of rainfall seepage,and the less obvious it is otherwise.