Deformation characteristics and layout optimization of roadway in complex jointed rock mass: a case study based on discrete element method

Complex jointed rock masses are common in nature. When a roadway is located in complex jointed rock mass, numerous joints can weaken the strength of surrounding rock, resulting in large deformation of the roadway and impact on mine production. In this paper, a DFN-DEM jointed roadway model was constructed based on discrete element method, with the failure characteristics and layout optimization of roadway analyzed. Also, the mechanical properties of jointed rock masses with different sizes and rotation angles were numerically investigated. And the failure and deformation characteristics of jointed roadway with different layout angles were analyzed. The results demonstrated that the UCS of jointed rock masses under different loading directions are significantly different, with an RVE size of 6 m. UCS of the jointed rock masses reaches maximum value at the rotation angles of 30 degrees and -60 degrees, and the average UCS of rock masses has a positively relationship with the joint density P30. The shear instability of joints results in the macro-failure of rock masses, and brings about the asymmetric failure of jointed roadway. The layout angle of jointed roadway can significantly affect its failure and deformation characteristics. With the roadway axial direction adjusted to -60 degrees relative to the direction of principal stress, the deformation degree of the surrounding rock reached minimum values. In engineering practice, an optimal layout angle and supporting of jointed roadway are effective for avoiding the large deformation of surrounding rock.