Abstract: Under deep mining conditions,geological conditions deteriorate,and fractured rock masses are prone to large deformation and failure. The discrete fracture network (DFN) in 3DEC software is applied to establish a synthetic rock mass (SRM) model considering different degrees of fragmentation in deep underground areas. The mechanical properties of highstress fractured rock masses under confining pressure loading conditions are studied,and the relationship between rock integrity coefficient,compressive strength,and elastic modulus is established. The experimental results show that rock masses with a high degree of fragmentation exhibit strong ductile failure characteristics under uniaxial compression tests;As the confining pressure increases,the compressive strength and plastic deformation of the stress-strain curve at the yield stage significantly increase with the same degree of fragmentation,and the amplitude of post-peak stress drop slows down;The micro cracks inside the rock mass first originate at the end of the joint surface and its intersection,and the larger the number of joints,the faster the crack development and connection;When subjected to high confining pressure loading,the failure mode of the specimen changes from tensile failure to shear slip failure. The failure characteristics of fractured rock masses are closely related to their degree of fragmentation and the stress-loading environment,which is an important reference for engineering construction and design.

Key words: deep mining,fractured rock mass,triaxial compression,mechanical properties,discrete fracture network