水位上升与荷载耦合作用下土坡稳定极限分析方法研究

边坡失稳产生的灾害不仅会给工农业生产带来巨大损失,也会对人民的生命财产安全造成巨大威胁。目前,滑坡灾害已与地震、火山并列成为全球3大地质灾害之一,其中由水库水位变化诱发的滑坡近来得到重视。因此,建立合理的边坡稳定性分析方法对预测以及防控滑坡灾害十分重要。实际中的边坡失稳过程往往在多种荷载因素的耦合作用下发生,但现有边坡极限分析等稳定性解析方法偏重于考虑单一荷载因素,难以合理考虑多类荷载耦合作用条件,缺乏对边坡稳定性依赖加载过程这一现象的合理解释。本文在极限分析原理的基础上,将水库区边坡所受荷载凝练为水位上升与坡顶加载的耦合作用。将水位荷载简化为水位线以下土体受到浮力以及黏聚力的减小,建立了一个土坡稳定性分析方法,编写了相应的数值计算程序,通过与离心模型试验结果进行对比验证了方法的有效性。该方法计算结果表明,边坡稳定性随坡顶荷载增加单调下降,而随水位上升表现出先降低后增加的非单调变化。因此,坡顶荷载与水位上升耦合加载过程中,边坡稳定性对于加载过程具有显著的依赖性。

STUDY ON SLOPE STABILITY UNDER COUPLING LOADING CONDITION BY LIMIT ANALYSIS METHOD

Slope instability will not only bring huge losses to industrial and agricultural production, but also pose a great threat to the safety of people's lives. At present, landslides have become one of the three major geological disasters in the world, together with earthquakes and volcanoes. Landslides are caused by a variety of factors such as reservoir water level change. The reservoir water level change induced landslides are particularly concerned. Therefore, it is of great importance to establish a reasonable slope stability analysis method for predicting and preventing landslide hazards. The actual slope instability process often occurs under the coupling effect of various loading factors. However, previous analytical methods such as the limit analysis method focus on the influence of single factor on slope stability and are difficult to reasonably consider coupling application of various factors. Accordingly, they cannot capture the path dependence of the slope stability. In this paper, we establish a model of a soil slope under the combination of top loading and water level change on the basis of the limit analysis method. We assume that the soil below the water level is subject to buoyancy and reduction of cohesion. The effectiveness of the model is verified by the centrifuge test results. The model predictions reveal that the slope stability monotonically decreases with increasing top load, and non-monotonically changes with increasing water level. Therefore, the slope stability is significantly dependent on the coupled loading process.