关键词: 顶板, 极限分析法, 数值模拟, 安全系数, 附加载荷

Abstract: In order to study the gob area roof stability of Qidashan iron mine, the numerical software FLAC^3D and limit analysis method were used to simulate the deformation and failure situation of the roof with different thickness under additional loading. In the simulation, the Mohr-Coulomb criterion was adopted, which can consider both the tensile and the shear failure of materials. The results show that when the roof thickness is less than 5.5 m, the tensile failure is the main mode. It will lead to the great increase of arch plastic zone areas. The strength reduction safety factor and the ultimate bearing capacity with the increasing roof thickness are not significant and have an approximately linear relationship. When the roof thickness is more than 5.5 m, the safety factor and ultimate bearing capacity are increased remarkably. The roof thickness is thus determined to be more than 5.5 m for the gob spacing of 10 m, which can ensure the roof stability under roof rock weight and additional loading. With the reduction of material parameters of cohesion c, internal friction angle φ and tensile strength at the same time, the distribution of the plastic zone is similar with the ultimate bearing capacity. Therefore, it is necessary to consider the effect of the tensile failure of gob area during the calculation of the safety factor and latent failure zone.