Abstract: The structural effect of fractured rock mass on equivalent mechanical parameters is studied by introducing a new synthetic rock mass technique based on the discrete element method (DEM). Through the controllable change of structural parameters in the three-dimensional (3D) rock mass structure network, the corresponding synthetic rock specimens are produced, and numerical simulations are carried out. The results indicate that equivalent mechanical parameters decrease with the increase of fracture density. Particularly, the equivalent elastic modulus is the most sensitive to the change of fracture density. With increasing the fracture dip angle, the equivalent elastic modulus increases and its standard deviation decreases. While strength parameters decrease first and then increase to form a U shape with increasing the dip angle. The equivalent mechanical parameters decrease with the increase of fracture size. Meanwhile, their standard deviations increase with the increase of the fracture diameter, and especially the uniaxial compressive strength is the most sensitive index. Moreover, the dispersions of the fracture size and dip angle have little influence on the equivalent mechanical parameters. This study can provide certain references for studying the structural effect of the fractured rock mass on equivalent mechanical parameters.

Key words: fractured rock mass, computer simulation, synthetic rock mass technique, structural effect, equivalent mechanical parameters