降雨诱发全-强风化岩边坡浅层失稳模型试验研究

以珠江－西江经济带先行试验区典型降雨诱发型滑坡为研究对象,引入流体力学相似原理以韦伯准则作为降雨相似标准,开展了3组降雨诱发滑坡全过程物理模型试验。分析了边坡对降雨入渗的响应规律、入渗过程对边坡变形的影响、边坡破坏过程与破坏模式,初步获得华南强烈风化地区降雨诱发滑坡形成机理与成灾降雨特征:①浅层岩土体风化强烈造成的高孔隙率是试验区降雨诱发滑坡的物质基础,非饱和岩土基质吸力消散是试验区降雨诱发滑坡的本质原因,降雨入渗后特定的基质势(含水率)分布是降雨诱发滑坡的条件。②降雨诱发全风化花岗岩滑坡灾害所需累积降雨量比强风化碎屑岩小,强风化碎屑岩滑坡滑动影响范围比全风化花岗岩大。③强暴雨诱发滑坡灾害所需累积降雨量比间歇性降雨小,强暴雨更易诱发滑坡,且诱发的滑坡规模更大。

Model Test on Shallow Failure of Fully and Strongly Weathered Rock Slope Induced by Rainfall

Taking the typical rainfall-induced landslides in the pilot test area of the Pearl River-Xijiang Economic Belt as the research object, we carried out three sets of physical model test on the whole process of rainfall-induced landslides by introducing the hydrodynamic similarity principle and taking the Weber number criterion as the rainfall similarity criterion. By analyzing the response law of slope to rainfall infiltration, the influence of infiltration process on slope deformation, the slope failure process and failure modes, we preliminarily obtained the formation mechanism of rainfall-induced landslide and the characteristics of disastrous rainfall in South China. (1) The high porosity caused by strong weathering of shallow rock and soil is the material basis of rainfall-induced landslides in the test area. The dissipation of matric suction of unsaturated rock and soil is the essential cause of rainfall-induced landslides in the test area. The specific matric potential (water content) distribution after rainfall infiltration lays the condition for rainfall-induced landslides. (2) The cumulative rainfall needed for totally weathered granite landslide disaster induced by rainfall is smaller than that of strongly weathered clastic rock landslide, but the sliding influence range of strongly weathered clastic rock landslide is larger than that of fully weathered granite landslide. (3) The cumulative rainfall required for landslide disaster induced by heavy rainfall is smaller than that induced by intermittent rainfall. Heavy rainfall is more likely to induce landslide, and the induced landslides are larger in scale.