Numerical simulation study on the evolution law of mine pressure in deep mining

The evolution law of surrounding rock pressure in deep mining is explored in this paper by analyzing the stress, displacement, and failure progress of surrounding rock in the deep mining of Beiminghe Iron Mine by in situ monitoring and FLAC(3D) numerical simulation. The evolution characteristics of surrounding rock deformation of different layer roadways during the entire excavation and mining process are observed, with results showing that movable support pressure exists in the excavation and mining process of the roadways. In the process of roadway excavation, vertical stress increases at the pillars, while horizontal stress increases at the roof and floor of the roadway. When the roadways are mined, the stress relaxed area is 0-4 m from the mining face, the stress increase area is 4-60 m from the mining face, and the original rock stress area is 60 m from the mining face. During the mining period, the horizontal convergence displacement of two sides of the roadway is lateral expansion caused by vertical stress, while vertical deformation of the roof and floor of the roadway is predominately caused by horizontal stress extrusion. The mining of upper layer roadways has a certain influence on lower layer roadways, and the mining of the same layer roadways only has a significant impact on adjacent roadways. With the increase of mining depth, the stress concentration becomes more obvious, and the convergence of vertical displacement and horizontal displacement of rock strata increases. In addition, shear failure occurs in overburden strata and shear tension failure occurs in the floor of the roadway.