饱和状态下岩体抗剪切特性试验研究

Experiment study on shear characteristics of saturated rock mass

采用自制的试验装置对饱和状态下的岩体试件进行剪切试验,绘制出相应的变形和强度曲线,得出饱和状态下岩体的抗剪性能参数,并将其与天然状态时的结果进行对比,以便定量地分析各参数的下降幅度。试验结果表明:岩体抗剪强度不仅与岩体所受法向应力有关,而且与岩体含水量有关;饱和状态下岩体的抗剪强度比天然状态时的抗剪强度平均减小11.17%;与天然状态相比,粘聚力c、内摩擦角φ的变化也比较明显,c平均下降16.09%,φ平均下降10.02%。这充分说明在降雨条件下,尤其是大降雨发生时,岩体失稳的可能性会大大增加,这也正是地质灾害经常在降雨后发生的主要原因。

By using homemade experiment equipment, the shear test of saturated rock masses was carried out, the deformation and intensity curves of different samples were drawn, and the values of shear parameters in saturation were obtained. Compared with the results in natural state, the decline extent of shear parameters was analyzed quantitatively. The test results show that the shear strength of rock mass is relevant to not only positive stress but also to water content of the rock mass. The shear strength of rock mass in saturation decreases by 11.17% averagely compared with that in the natural state, and the decreased extents of cohesive force and internal frictional angle are also obvious in saturation： The average decreasing rate of cohesive force and the internal frictional angle are 16.09% and 10.02%, respectively. It is demonstrated that the possibility of destabilization of rock mass will greatly increase under rainfall conditions, in particular the large rainfall occurs, and this is also the main reason why geologic hazards often occur after rainfall.