附加载荷作用下空区顶板稳定性分析

以齐大山铁矿为工程背景,利用FLAC3D软件和Mohr-Coulomb屈服准则,通过极限分析方法和数值模拟技术相结合,研究了在附加载荷的作用下,不同厚度的空区顶板的稳定性.计算结果表明:当顶板厚度小于5.5 m时,顶板的破坏以受拉伸破坏为主,破坏区呈"拱"形向围岩内发展,此时的安全系数和极限承载能力随顶板厚度的变化并不明显,近似呈线性关系;当厚度大于5.5 m后,顶板的安全系数和极限承载能力随顶板厚度增大而迅速增加,因而建议对于10 m跨度的空区,其顶板安全应不小于5.5 m.对岩体黏聚力、内摩擦角和抗拉强度同步进行折减得到破坏区与增量加载的计算结果相似,得到的安全系数要小于仅折减黏聚力和内摩...

Analysis on Roof Stability of Concealed Gob Area Under Additional Loading

In order to study the gob area roof stability of Qidashan iron mine,the numerical software FLAC3D 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.