Large deformation theory of rheology and structural instability of the surrounding rock in deep mining roadway

Compared with the shallow roadway,the deep roadway,especially the mining roadway in kilometer deep mines,has high in-situ stress and strong mining influence,which leads to the large deformation,long duration and seri- ous damage of the surrounding rock of the roadway. The current theory cannot scientifically explain the deterioration, large deformation and damage mechanism of the surrounding rock of the deep mining roadway. The theory of large de- formation and failure of roadway surrounding rock under the condition of deep mining has become one of the major is- sues facing the deep coal mining. Therefore,the concept of mining coefficient is put forward based on the stress intensi- ty ratio,partial stress and gradient stress,field investigation and experiment,laboratory experiment,numerical simula- tion and theoretical analysis. From the point of view of mechanical essence and engineering application,the concept of strong mining and large deformation of roadway is defined,its scientific connotation is discussed,and the quantitative evaluation method of strong mining and large deformation is preliminarily put forward. On this basis,based on the stress environment and large deformation characteristics of the surrounding rock of the deep mining roadway,the theo- retical framework of the rheology and structural instability of the surrounding rock of the deep mining roadway is pro- posed. Its core idea is the structural movement of the surrounding rock,the deterioration of the surrounding rock,the crack expansion induced by the gradient stress and deviatoric stress,the large deformation caused by the rheology and structural rheology of the soft rock,and the long-term expansion of the fractured rock mass. The basic problems include the stress path of the surrounding rock of the deep mining roadway,the action mechanism of the deviatoric stress and the gradient stress considering the stress path on the surrounding rock of the roadway,and the anchorage bearing struc- ture flow of the surrounding rock of the roadway large deformation,instability of surrounding rock structure and so on. Partial stress and gradient stress lead to the expansion and shear sliding of the surrounding rock in the bearing area, and the shear sliding of the surrounding rock in the bearing area produces thrust to the roadway,and the expansion and thrust lead to the structural slip,rheology and integrity extrusion of the shallow anchorage. The traditional rheology of soft rock upgrades to the rheology of soft rock and the structural rheological deformation of anchor solid. The large de- formation of the surrounding rock structure of the roadway includes the large deformation of the whole movement caused by the large structure instability of the overlying strata and the large deformation of the movement of the frac- tured rock mass in the loosening circle. Based on the interaction of deep environment,deep rock mass and strong con- struction disturbance,the theory of rheology and structural instability of surrounding rock in deep mining roadway is put forward,which reveals the temporal and spatial evolution law of stress field and the mechanism of large deformation and failure of surrounding rock in deep mining roadway.