Study On Topological Evolution Law And Stability Of Stress Field Of Roadway Surrounding Rock During Creep Process

The deformation,damage and even instability of roadway are closely related to the distribution and change of surrounding rock stress of roadway.At present,two traditional visualization diagrams of principal stress component contour diagram and principal stress vector diagram are needed to study the change law of stress field.The principal stress s component contour diagram needs three diagrams to fully describe the stress distribution information.The principal stress vector diagram is difficult to read because of its complex lines and can’t reflect the stress relationship at different positions.To solve this problem,based on the tensor field visualization method,this paper proposes to characterize the stress field of surrounding rock by the topology of principal stress trajectories.In this method,the distribution characteristics of the principal stress trajectories and the location and type of degenerate points are taken as research objects to analyze stress field,and then the stability of surrounding rock is analyzed by summarizing the topological evolution laws of principal stress trajectories.Firstly,the stress field can be regarded as a tensor field,and tensor topology is a method of tensor field visualization,so tensor topology can be used to visualize the surrounding rock stress field.Then the relevant theory of tensor topology is used to illustrate the scientificity and feasibility of the representation of stress field topology by principal stress trajectories,and discusses the relationship between the stability types of degenerate points,topological bifurcation,and the stability of surrounding rock from the mathematical point of view.To find out the topological evolution laws of stress field,this paper takes different lateral pressure coefficients,different roadway cross-section shapes and whether the roadway is supported or not as independent variables,and through numerical simulation,obtains the principal stress trajectories diagram and plastic zone diagram of surrounding rock in the process of creep.Then,a series of diagrams are compared and analyzed,and the distribution characteristics of principal stress trajectories in roadway creep process are summarized,and then the relationship between the topological evolution laws of stress field,stress field structure and roadway instability are revealed.Secondly,based on the relationship between the topological evolution laws of stress field and the instability of roadway,suggestions are put forward to maintain the stability of roadway surrounding rock based on controlling the topological shape of principal stress trajectories.Finally,the correctness of the visualization method and the suggestion to maintain the stability of the roadway are verified by the numerical simulation of the actual roadway rock mass structure and stress conditions in the industrial experiment.The results show that the principal stress trajectories and degenerate points can effectively topologically characterize the stress field of surrounding rock,and the summarized topological evolution law of stress field accords with the failure law of surrounding rock during creep,and the relevant suggestions for maintaining the stability of surrounding rock of roadway also meet the actual support requirements.Therefore,it is scientific and feasible to use the principal stress trajectories and degenerate points topology to characterize the stress field.This visualization method provides a new idea for stress analysis of surrounding rock.