降雨条件下双层土斜坡稳定性的简化分析方法
Simplied Method for Stability Analysis of Two-layered Slope Under Rainfall Infiltration
-
摘要:
Green-Ampt模型原理简单、使用方便，在浅层滑坡的降雨入渗分析中有很大的应用潜力。推导了适用于双层土斜坡的Green-Ampt降雨入渗分析模型，并给出了降雨入渗量随降雨时间变化的解析表达式。提出的模型预测的孔隙水压力分布与Richards模型预测结果类似。在此基础上，基于极限平衡法提出了双层土斜坡的安全系数计算方法。研究表明，随着降雨时间的增加，湿润锋位置逐渐下移，安全系数随着也慢慢减小。当下层土强度较高时，最危险滑动面位于第一层土体的底部，在一段时间内安全系数将不随时间发生变化。但当雨水入渗深度足够大时，最危险滑动面重新位于湿润锋位置处，此时安全系数将随着入渗深度的增加再次增加。斜坡安全系数降低的速率随着降雨强度和斜坡坡度的增加而增加，因而在相同条件下高强降雨及坡度较陡斜坡更为危险。方法计算简便，可以更方便的应用于工程实践，并且具有继续研究的价值。 Abstract:Due to its ease to use, the Green-Ampt model is potentially very useful for infiltration analysis for predicting of slope failure. In this study, the governing equation for infiltration analysis on sloping surfaces in layered soils is derived. The depth of wetting front predicted from the modified Green-Ampt model is close to that predicted based on Richards' function. Based on the limit equilibrium method, the safety factor calculation.in layered slope is proposed. Research shows that along with the increase of the rainfall, the wetting front position down gradually and the safety factor decreases.When the lower soil's strength is higher, the most dangerous sliding surface will be at the bottom of the first layer of soil, the safety factor will not change with time. However, when the infiltration depth is large enough, the most dangerous sliding surface will locate at the wetting front again, the safety factor will change.And, the safety factor is influenced by the rainfall intensity and slope angle, thus the slope will be more instability under the condition of high rainfall strength and steep slopes. In this paper, the modified method is simple, can be more easily applied to the engineering practice, and has value to further study.
下载:
