Experimental Study of the Plastic Zone and Stress Asymmetric Distribution in Roadway Layered Surrounding Rocks

Featured Application The research in this paper is of great significance for grasping the development pattern of the plastic zone and the stress distribution of the roadway (tunnel) layered surrounding rock. It has an important reference value for the support problem of a roadway (tunnel) and the design of the surrounding rock support scheme. A three-axis experimental simulation model was established for a roadway with layered surrounding rock by a 20 MPa true triaxial analog simulation equipment, and the corresponding layered surrounding rock numerical simulation model was established by discrete element software. The simulation results showed that the deformation of the roadway layered surrounding rock showed asynchronous deformation with time and asymmetric deformation in space. The measured results of the multipoint displacement meter inside the surrounding rock showed that the order of displacement of surrounding rock from the four corners of the roadway to the center of the roadway were upper right, lower left, upper left, and lower right. Under the influence of the surrounding rock bedding, the shape of the plastic zone of the roadway surrounding rock was irregular. In the area where the rock layer and the surface of the roadway were tangent and in the vertical area between the rock layer and the surface of the roadway, the plastic zone had a large development depth. In other regions, the development depth of the plastic zone was smaller. As a result, the stress values obtained at the monitoring points in the surrounding rock at the same distance from the roadway surface were different, and the stress increase value of the monitoring points in the plastic zone was not large (No. 929). With the expansion of the plastic zone, the monitoring point change from outside the plastic zone to inside the plastic zone, its stress first increased and then decreased (No. 2 and No. 872). The experimental results are of great significance for understanding and controlling the development law of the plastic zone of a layered inclined rock roadway and the deformation control of the roadway layered surrounding rock.