关键词: 饱水冻结, 裂隙倾角, 三轴压缩, 力学性质, 破坏模式

Abstract: In order to explore the mechanical properties and failure mechanism of fractured rock mass in cold region, conventional triaxial compression tests were carried out on saturated sandstone with different fracture dip angles under -10℃ freezing environment. The results show that the geometric characteristics of fractures have a great influence on the development of stress-strain curves of sandstone during loading. The initial section of the stress-strain curve is "convex", which is due to the fact that the load is mainly borne by the ice body in the pores and fissures of the rock mass. The peak strength, elastic modulus and shear strength parameters of sandstone are linearly positively correlated with fracture dip angle, while Poisson's ratio and volume strain are negatively correlated with fracture dip angle, but the variation range is not obvious. The low temperature freezing environment enhances the degree of cementation and friction between sandstone particles to a certain extent, so that different fractured sandstones show the characteristics of monooblique shear failure, and there are no obvious wing cracks and secondary cracks except the oblique cracks in the main shear plane. By establishing the damage evolution equation considering the strength and deformation of fractured sandstone, it is found that with the increase of fracture dip angle, The stress levels of initiation and dilatancy of sandstone increase gradually, and the drop state of post-peak stress-strain curve is more obvious. it shows that the elastic stage of the stress-strain curve becomes longer, the plastic stage becomes shorter, the brittleness of sandstone increases and the ability to resist plastic deformation decreases