Abstract:
To study the mechanical characteristics of composite rock mass under static loading, static loading tests of composite rock mass with different joint angles were conducted using a servo pressure testing machine, and the compressive strength and crack propagation of the composite rock mass were compared and analyzed. Taking into account the inhomogeneity of rock materials, an elastic damage constitutive model was established to reproduce the progressive damage evolution process, and the energy dissipation characteristic was presented during loading. The results show that: With the increase of joint inclination angle, the compressive strength of the composite rock mass gradually decreases, reaching a minimum of 18.0 MPa at 45°. Then the compressive strength begins to increase significantly, reaching a maximum of 43.0 MPa at 90°. The strength of the composite rock mass shows a significant inverted U-shape change with the increase of joint inclination angle. An elastic damage constitutive model was established based on Weibull distribution. The constitutive model was verified by comparing the results of uniaxial compression and Brazilian splitting tests with the simulation results. For composite rock masses with different joint angles, the damage zone starts to originate on the coal side and expands along the joints until it fails. The simulation results are in good agreement with the test results, realizing the characterization of the rock damage process under static loading. Strain energy density begins to concentrate on the coal side and expands along the joints, showing the spatio-temporal distribution characteristics of energy concentration.