In order to study the damage and fracture process between particles meso-contact

the tensile damage variable and shear damage variable were introduced into parallel bond model to characterize the deformation

strength and energy evolution characteristics of particle bonding contact based on the Particle Flow Code(PFC3D). According to the maximum stress criterion

the bond damage initiation criterion was determined

and the contact model was redeveloped by C++ language. The results of tensile

shear

bending and torsion tests of single contact were compared with the theoretical results

and the accuracy of the parallel bond contact model considering damage was verified. A three-dimensional meso discrete element model was established to simulate the uniaxial compression test of sandstone and triaxial compression test of granite

showing the applicability and accuracy of the model. Based on this study

the results show that the damage evolution coefficient has a noticeable effect on the elastic range

peak stress and softening rate of the whole stress-strain curve; the evolution process of bond damage

crack germination

propagation and coalescence in different stages of the stress-strain curve was comparatively studied; the evolution law of elastic strain energy and dissipative energy was further studied

and dissipated energy was introduced. It was explained that the larger the damage evolution coefficient is

the faster the decreasing of stress-strain curve is after reaching the peak stress.