Distribution characteristics of deviatoric stress field and failure law of roadway surrounding rock under non hydrostatic pressure

The distribution law of deviatoric stress field and strain energy density of roadway surrounding rock under the condition of three dimensional stress and non hydrostatic pressure is studied by theoretical analysis,so as to explore the failure law of roadway surrounding rock.The correctness of theoretical results is verified by numerical simulation results of roadway plastic zone and field engineering examples.The results show that (1) under the condition of non hydrostatic pressure,the distribution law of deviatoric stress field of roadway surrounding rock is obviously different in different dominant stress fields.In the σx dominant stress field,the deviatoric stress of roadway roof and floor is greater than that of sidewalls.In the σy dominant stress field,the difference of deviatoric stress between the roof and floor of roadway surrounding rock and that of sidewalls is not significant.In the σz dominant stress field,the deviatoric stress of sidewalls of roadway is greater than that of roof and floor.The change of the dominant stress value will cause the change of the deviatoric stress distribution value of the surrounding rock,but will not cause the change of the distribution form of the deviatoric stress.(2) Under the condition of equal p and q,in the σx and σy dominant stress field,the strain energy density of roadway roof and floor is greater than that of sidewalls.While in the σz dominant stress field,the strain energy density of sidewalls of roadway is greater than that of roof and floor.In the case of equal p and unequal q,the strain energy density of roof and floor and sidewalls of roadway increases as the increase of deviator stress ratio M in the three dominant stress fields.In the case of equal q and unequal p,the strain energy density of roadway roof,floor and sidewalls increases as the decrease of deviatoric stress ratio M.(3) Under the state of three dimensional stress,the distribution law of strain energy density of surrounding rock can reflect the shape of plastic zone.When M1,the strain energy density of roadway surrounding rock will appear “8” shape and “X” shape distribution.In the σx dominant stress field,it should pay attention to the support of roof and floor of roadway.In the σy dominant stress field,when the surrounding rock condition is poor,it should pay attention to the full face support.In the σz dominant stress field,the attention should be paid to the “X” shape plastic zone expansion of surrounding rock.(4) The results show that the distribution of deviatoric stress field and strain energy density of surrounding rock of 1021 roadway in Huipodi coal mine is distributed in an oblique “8” shape,the distribution of deviatoric stress field and strain energy density of surrounding rock and the engineering site verify each other.