降雨对路堤边坡渗流规律及稳定性影响分析

Influence of Rainfall on Seepage and Stability of Embankment Slopes

基于ABAQUS有限元软件模拟分析了降雨条件下某高速公路路堤边坡的基质吸力变化规律,并用强度折减法分析其稳定性。结果表明:在降雨总量相同时,降雨持续时间越长,边坡的渗透深度也就大。在降雨总量相同时,降雨强度越大,越容易在边坡表层形成暂态饱和区,这与土壤的渗透系数等也有关系;降雨对边坡位移的发展具有促进作用,与降雨强度、降雨从持续时间和边坡坡度等有关。当降雨结束后,由于雨水下渗,边坡的竖向位移会有回弹,而水平位移将继续发展;降雨对边坡的稳定性有不利作用,降雨越剧烈越容易造成边坡安全系数的降低。当降雨到达一定程度时,坡脚区域将会首先进入塑性区,而后向上发展出滑移面,最终造成边坡失稳。

The settlement and stability evaluation of the expressway embankment slope have become more and more mature. This paper analyzes the variation of the matrix suction of an expressway embankment slope under the rainfall conditions. The stability of the slope is evaluated by the strength reduction method using ABAQUS finite element software. The results show that: when the total amount of rainfall is the same, the longer the rainfall duration, the greater the infiltration depth of the slope. The longer the rainfall duration is, the deeper the infiltration depth is. When the total rainfall remains the same, the greater the rainfall intensity is, the easier it is to form a transient saturation zone on the surface of the slope. Because the seepage will be hindered by the slope soil, when the rainfall intensity is strong enough, the rainwater has no time to flow down, so it will accumulate in the surface soil, thus forming a transient saturation zone. It is also related to the permeability coefficient of soil. The rainfall can promote the development of slope displacement, which is related to rainfall intensity, rainfall duration and slope gradient. When the rainfall is over, the vertical displacement of the slope will rebound and the horizontal displacement will continue to develop due to the rainfall infiltration;the rainfall has an adverse effect on the stability of the slope, and the more severe the rainfall is, the easier it is to reduce the safety factor of the slope. When the rainfall reaches a certain degree, the slope toe area will first enter the plastic zone, and then develop the sliding surface upward, resulting in the slope instability.