Study On Stress Field Structure Of Roadway Surrounding Rock And Its Stability

Stress analysis is an important part of research on the control of roadway surrounding rock in coal mines.At present,there is a lack of effective means for visualizing and describing the stress field structure.To solve this problem,the principal stress trajectories are used to visualize the stress field,and the structure of the stress field is characterized by the location and type of degenerate point in the principal stress trajectories diagram and the distribution pattern of the principal stress trajectories coil.In this paper,the characterization and stability relationship of the stress field structure of roadway surrounding rock are in depth studied by means of theoretical analysis,numerical simulation and field verification.The stress field is the tensor field,and the structural characteristics of the stress field can be described with the help of related theories and methods of tensor topology.However,in tensor topology,the structure of the tensor field is usually described by means of super streamline(main stress traces),and the structure of the super streamline is mainly controlled by the location and type of degenerate point in the field.Therefore,in this paper,the principal stress trajectories and related concepts are described in detail and the precise definition of the topological structure of the roadway surrounding rock stress field is given.In order to find the relationship between the stability of the roadway surrounding rock and the structure of stress field,a numerical simulation method was used to numerically analyze a series of typical roadways,and then the general rule of the shape distribution of the principal stress trajectories and relationship between the stress field structure and roadway instability failure were revealed in the roadway surrounding rock.Combining the obtained rules and the ideas of nonlinear dynamics to analyze the stability of the surrounding rock,several stability criteria based on the topological structure of the surrounding rock stress field are concluded.Finally,the accuracy is verified in actual engineering cases.The study found that a relatively clear relationship between roadway surrounding rock failure and stress field structure.The principal stress trajectories can be used to characterize the stress field structure of roadway surrounding rock,which is mainly reflected by the shape of the principal stress trajectories and the location of the degraded point.Factors such as lateral pressure coefficient,rock material strength,roadway cross-section area and other factors all affect the shape of the principal stress trajectories,which is mainly reflected in the curvature of the principal stress trajectories coil and location form of the degraded point.The roadway surrounding rock easily undergoes severe plastic deformation in two situations:the topological structure of the stress field changes(the bifurcation phenomenon at the degraded point)and the position where the principal stress trajectories has a larger curvature.The more the principal stress trajectories coil tends to be round,the more stable the roadway is,on the contrary,it will be prone to instability.Therefore,from the perspective of the principal stress trajectories,as far as possible to make the principal stress trajectories coil round and away from the roadway,the stability of the roadway can be ensured.The stability analysis method of the principal stress trajectories can explain some surrounding rock control theories and methods at the present stage well,and has been verified in engineering examples.This method can provide a new idea for the study of roadway surrounding rock control theory in the future.