Hierarchical Constant Resistance Large Deformation Anchorage Structure And The Support Characteristics Study

With mining depth increasing, nonlinear large deformation would be prominent under the complicated environment of three “high” one “disturbance”. This would cause large roadway deformation, long deformation time, seriously destroyed surrounding rock and increasing failed supporting, which will make the roadway maintenance difficult. It is not so obvious to prevent large deformation when using the current roadway supporting. The supporting material cannot provide constant supporting resistance to controllably release deformation energy inside the rock mass. Therefore, it cannot be reached for the roadway stability control goal of supporting- surrounding rock interaction, neither meet constant resistance requirement under different surrounding rock environment in terms of deep surrounding rock with nonlinear deformation and long deformation time features. This paper introduce a new hierarchical constant resistance large deformation anchorage structure that can solve the large deformation problem during deep soft rock roadway reinforcement. The anchorage structure performances are studied by laboratory test, theory analysis and numerical simulation. The main conclusions are as follows:(1) According to the control theory of constant resistance large deformation, a new anchorage structure is developed that can reach hierarchical constant resistance by setting different constant resistance. This paper introduces structure character, technical parameter and function principle. The specific function of each structure component is detailed. The specific size of each structure component is calculated. And the joint strength of each structure component is checked.(2) Static tensile test of hierarchical constant resistance large deformation anchorage structure is performed to verify the hierarchical constant resistance mechanical properties under tensile force, determine all levels constant resistance and deformation value. Then the mechanical characteristic is studied through numerical simulation based on ANSYS of which the protection sleeve is under shear force. The shear stress caused by broken surrounding rock sliding deformation at the orifice to verify its protection effect for the cable in real supporting during the supporting process of the roadway.(3) According to the mechanics character of the constant resistance large deformation anchorage structure, the coupling structure model of anchorage structure and surrounding rock is established based on interaction of the cable and surrounding rock. The solution method is put forward to solve the problem of the rock mass reinforced by the anchorage structure on the basis of plastic incremental theory. The equilibrium equation and the displacement compatibility equation of the reinforced rock mass micro-unit are also deducted.(4) Based on the FLAC 3D model of the initial cable element, the hierarchical constant resistance criterion and fracture failure criterion are embedded into the FLAC 3D main program by FISH language programming. A new hierarchical constant resistance cable element model is obtained to effectively simulate the feature of hierarchical constant resistance. The simulation solution process is detailed.(5) By static tensile test, the practicability and accuracy of the element model are verified. It is also simulated the bolt-shotcrete support by using the ordinary cable and the hierarchical constant resistance large deformation anchorage structure under different depth and different side pressure coefficient. It is analyzed the hierarchical constant resistance large deformation, fracture failure and the following influence effect. The simulation results reveal the supporting characteristics of the hierarchical constant resistance.