Research on surrounding rock control technology of deep roadway based on butterfly failure theory

At present, roadway surrounding rock control is still one of the major problems in deep mining of coal resources. The formation and development of the plastic zone of the surrounding rock is the main cause of large deformation and failure of roadway. In this paper, the formation and development of plastic zone and its influence on the stability of roadway are studied by numerical simulation. Through theoretical analysis and laboratory experiments, the mechanism of bolt support is studied and the internal relationship between support and surrounding rock deformation is expounded. Based on butterfly failure theory, the control principle of surrounding rock in deep roadway is discussed, and the control technology of surrounding rock in deep roadway is put forward and applied in engineering. The results show that: ① Bolt support can effectively reduce the deformation of surrounding rock, but cannot control the deformation of roadway. Under the existing support level, there is some uncontrollable deformation of surrounding rock in roadway, namely ‘given deformation’. And the ‘given deformation’ increases with the increase of roadway buried depth. ② The control effect of bolt support for roadway surrounding rock dilatancy, slip and other non-continuous deformation is obvious, but for the continuous deformation of intact rock is very limited. Therefore, bolt support mainly controls the total deformation of roadway by controlling the discontinuous deformation of rock mass in plastic zone of roadway. ③ The total deformation of roadway mainly includes ‘given deformation’ and ‘residual deformation after supporting’. The main way of roadway surrounding rock control is to reduce ‘ residual deformation after supporting’. ④ The mechanism of bolt support requires that the anchor foundation must always be located in the complete rock mass. Therefore, the shape of plastic zone after roadway excavation and the development law of plastic zone in the service period are very important for the design of bolt support. The difference of roadway plastic zone shape and its mechanical response determines that the roadway support must be designed differently.