Excavation damage mechanism of deep buried layered fractured rock mass based on three-dimensional bonded block damage model

Abstract

Under complex mineralization, the geological environment of deep mining projects is often accompanied by fractured rock masses. The existence of structural planes and cracks control the mechanical behavior of fractured rock masses. To describe the mechanical response mechanism of deep buried fractured rock mass, a three-dimensional bonded block damage constitutive model (BBDM) is proposed in this paper. Based on the damage characteristics of rock mass, the model will degrade the tensile strength, cohesion, dilation angle, normal and shear stiffness parameters of the joint based on the fracture energy value when the joint is in tension and shear yield state, and make the model eventually degenerate into a pure friction Mohr-Coulomb model under zero cohesion. Meanwhile, taking a deep buried roadway excavation project as the research background, the 610 m main slope excavation process is simulated by using the BBDM. Combined with the field test results, the stress, displacement and joint damage law of the surrounding rock excavation process are analyzed. The results show that in the closer position to the side wall, the potential interlayer fracture damage is larger, and the damage mechanism is mainly tensile damage. With the increase of the distance from the side wall, the damage degree gradually decreases, and the damage mechanism becomes mainly compressive shear damage, and eventually transitions to the state of no damage to the cracks. The research results reveal the damage process and failure mechanism of interlayer fracture in fractured rock bodies, which deepens the understanding of the mechanical response of deeply buried fractured rock masses and is significant for ensuring the stability of surrounding rocks and the safe and efficient production of the mining area.