天水黄土结构性变化诱发滑坡敏感性分析

The study on sensitivity of landslide induced by changes in loess structure

黄土高原地区黄土滑坡频频发生,尤其是近年来极端气候条件增多,集中强降雨导致甘肃天水地区黄土滑坡群发.2013年8月,在经历一周持续降雨之后,天水地区产生了大量的黄土滑坡以及黄土-泥岩接触面滑坡.黄土地区滑坡发生后一些滑坡的复活往往与黄土的结构性存在紧密联系.选取天水花南村滑坡后壁黄土为研究对象,利用GDS三轴仪对滑坡区黄土原状样和重塑样进行了固结不排水三轴压缩试验.试验结果表明,原状黄土表现出明显的应变软化特征,而重塑黄土的应变软化现象急剧减小,二者的孔隙水压力变化特征也有差异.同时基于三轴试验结果,绘制了原状黄土和重塑黄土的应力路径图,应力路径图再次证实了重塑样应变软化减小的现象.孔隙水压力随轴向应变变化图中可见,剪切初始阶段,重塑样的孔隙水压力增加较原状样更为迅速,对于滑坡的诱发更加敏感.

The loess landslide occurred frequently in the region of loess plateau in recent years. The extreme weather conditions and the heavy rainfall made the loess landslide become more than before in Tianshui,Gansu Province. A mass of loess landslide and loess-mudstone interface landslide triggered in Tianshui after a weekly continuous rainfall in August 2013. The resurrection of the loess landslide is often closely linked with the structure of loess. The undisturbed loess and remolded loess samples were chosen in the scarp of Huanancun landslide to operate consolidated undrained triaxial test by GDS triaxial apparatus. The results showobviously that the strain of undisturbed samples were strain softening,and the strain softening in remolded samples were weakened sharply. The result of strain softening was also undertaken by the stress path. The changes of pore water pressure in undisturbed and remolded samples were different from each other. At the beginning of shearing,the pore water pressure in the undisturbed samples increased slower than in the remolded samples. So the remolded loess was more sensitivity to the landslide than the undisturbed loess.