RJM BASED NUMERICAL STUDY OF STRENGTH AND FAILURE MODES OF ROCKMASS WITH DISCONTINUOUS JOINTS

The Roughness Joint Model(RJM)considering JRC is established in Matlab program. Simplified sinusoidal curves are used to represent roughness joints. Then it is introduced into the Particle Flow Code to conduct the uniaxial compression test. We compare the stress-strain curves of intact rock mass, linear fractured rock mass and RJM rock mass, and change the fracture inclination(angle with horizontal direction)α, rock bridge angle β, fracture density γ. Then numerical models of fractured rock mass with different fracture distributions are established to conduct a series of numerical simulation tests. By monitoring the initiation and propagation of secondary fractures, the damage process of jointed rock is analyzed. Findings can be drawn as follows. (1)The presence of fractures significantly reduces the strength of rock mass. The peak strength and peak strain of RJM model are higher than those of linear cracks. (2)The compression strength of rock mass increases with the increase of joint inclination and decreases with the increase of fracture density, but changes in a nonlinear law with the fracture bridge angle. The peak strength at rock bridge inclination angle of 45°is the lowest, peak strain is the minimum. (3)The distribution of fractures has influence on failure mode, The expansion of the micro-fissures reflects the anisotropy of the mechanical properties of the rock mass. (4)Increasing the fracture density at different dip angles can reduce the strength of the rock mass in different level. When the dip angle is 75°, the density has the least influence on the strength, but at 30° and 60° the influence is the greatest.