强降雨作用下花岗岩全风化土坡致灾现场模型试验研究

Field Model Test of Disaster Caused by Granite Completely Weathered Soil Slope under Heavy Rainfall

花岗岩全风化边坡崩塌或滑坡是赣南地区最为频发的地质灾害,强降雨及人工切坡是其主要诱发因素。选取该地区一处花岗岩全风化人工切坡,开展人工降雨模拟边坡破坏现场试验。通过分析强降雨作用下坡体含水率、孔隙水压力、变形位移的变化规律及边坡破坏过程,探究花岗岩风化土坡的失稳机制。结果表明:含水率和孔隙水压力对降雨过程有着较为明显的响应;花岗岩全风化土坡变形破坏的主要判断依据是含水率和孔隙水压力的波动陡增;降雨入渗导致土体基质吸力减小,从而强度降低是花岗岩全风化土坡变形的主要原因;强降雨作用下花岗岩风化土质边坡的破坏模式为:先局部坡面滑塌,随后出现裂缝,最后整体大范围垮塌。

The collapse or landslide of granite fully weathered slope is the most frequent geological disaster in southern Jiangxi,and the heavy rainfall and artificial slope cutting are the main inducing factors.The field test of artificial rainfall simulating slope failure was carried out on a fully weathered artificial cut slope of granite in this area.The instability mechanism of granite weathered soil slope was explored by analyzing the variation law of slope water content,pore water pressure,deformation and displacement and slope failure process under heavy rainfall.The results show that water content and pore water pressure have obvious response to rainfall process.The main basis for judging the deformation failure of granite slope is the fluctuation of water content and pore water pressure.The main reason for the deformation of the weathered granite slope is that the soil matric suction decreases due to rainfall infiltration.Under the action of heavy rainfall,the failure mode of granite weathered soil slope is as follows:first partial slope slide,then cracks appear,and finally the whole large-scale collapse.