Study on stress distribution characteristics of roadway surrounding rock damaged zone under non-hydrostatic pressure

The stress state of surrounding rock is closely related to the stability of the surrounding rock of the roadway,which is an important subject for studying the safe mining of deep coal resources,and also an important theoretical basis for studying the optimal design of roadway support.In engineering practice,the surrounding rock of the roadway has the characteristics of non uniformity.Therefore the research on the stress distribution characteristics of the surrounding rock under the condition of non hydrostatic pressure has theoretical significance and engineering guidance value.Taking the variation of the surrounding rock stress and displacement in circular roadway as the research object,the theoretical calculation model under the condition of non hydrostatic pressure was established,and the stress and displacement of the surrounding rock damaged zone and plastic zone of circular roadway under non hydrostatic pressure were given.Taking the 902 working face haulage roadway in the north 2nd mining area of Daxing Coal Mine as an example,the characteristics of the stress and displacement of the surrounding rock damaged zone and plastic zone with the buried depth and lateral pressure coefficient were compared and analyzed,and the numerical analysis was applied.The numerical excavation model of circular roadway was established,and the variation of the damaged zone of surrounding rock under roadway excavation under different buried depth conditions was simulated.The numerical results were compared with theoretical calculations to evaluate the stability of surrounding rock.The results show that the change of surrounding rock normal stress is more severe than radial normal stress after tunnel excavation,which shows that the main form of surrounding rock failure is along the longitudinal crack.Due to the different deformation characteristics of surrounding rock in different areas,the values of the physical and mechanical parameters such as cohesion and internal friction angle are different,which lead to the discontinuity of the surrounding rock boundary stress.When the roadway is buried,the radius of the damaged zone and the plastic zone increases linearly with the increase of the buried depth in a certain depth.When the depth is small,the surrounding rock crushing area of the roadway is small,and the roadway is in a relatively stable state.When the buried depth is large,the left and right gangs of the roadway are more susceptible to instability and damage than the top and bottom of the roadway.The ratio of the radius of the plastic zone and the damaged zone decreases with the increase of buried depth and lateral pressure coefficient,and with the depth of buried increasing,the influence of the lateral pressure coefficient on the plastic zone and the damaged zone of the surrounding rock gradually decreases.When the buried depth increases to a certain extent,the stress state of the surrounding rock tends to a hydrostatic pressure state;the surrounding rock reaches the limit equilibrium state when the buried depth reaches 1 500 m.