Sandstone is encountered in many hydropower projects in China, and its permeability evolution characteristics during the deformation process are one of the most important issues in engineering design. In this study, microstructure observation and mineral content analysis of a sandstone are performed, and triaxial flow experiments under different fluid pressures are carried out. The experiment results show that the permeability evolution with volumetric strain is associated with microcrack development in the process of rock deformation and failure. The volumetric strain is closely related to the permeability and fluid pressure, and it plays a role of linking the flow field and the stress field. A conceptual model is suggested to describe the permeability evolution of the rock. Scanning electron microscope analysis results on some failed specimen pieces illustrate that the fluid pressure plays a role in the development of microcracks. A high fluid pressure can accelerate crack propagation and rock f...

Soil-rock mixture is a widely distributed geological material in mountainous regions, where slope stability is an important issue. To investigate the influence of rock on slope stability, firstly, rocks in SRM are generated and then SRM slope models are simulated based on the finite difference method (FDM). The impact of various characteristics of rocks on slope factor of safety (FOS) is studied systematically by using the reduced strength method. The characteristic of rock considered include rock content, number of rock edges, aspect ratio, rock size and inclination of rock. The simulations indicate that increasing the rock content can prevent the development of high strain region and improve slope stability. However, the aspect ratio of rock has negligible impact on the mean value of FOS. For slopes with 45° slope angle, rocks with 45° angle of inclination result in smooth potential sliding surface, whereas rocks with 135° angle of inclination lead to more tortuous potential sliding surfaces. Statistical indices are utilized to analyze the results of numerical modelling.