Gob-side entry stability analysis by global-finite andlocal-discrete modeling approach

In geotechnical engineering, the accurate evaluation of large-scale geotechnical engineering schemes before construction is very important. So the reliability of the surrounding rock support of the gob-side entry directly determines the success or failure of the gob-side entry remaining. To accurately evaluate designs of large scale engineering before the implementation, such as the gob-side entry retaining formed by roof cut and pressure releasing, this paper used the 3D finite element global model to obtain the local stress of the roadway surrounding rock. And then the local stress was applied as the boundary condition to the 3D discrete element roadway model to evaluate supporting effects of different support schemes during the gob-side entry retaining. Besides, based on numerical simulation, the coordinated support scheme of "constant resistance and large deformation cable + steel bolt + hydraulic prop + steel beam + U-shaped steel" was further proposed. The field test results shown that the support scheme can effectively control the deformation of the surrounding rock of the gob-side entry. The numerical simulation results were in good agreement with the field test results. So the feasibility and reliability of the numerical simulation evaluation method were verified by the field test results. Therefore, the global-finite and local-discrete modeling approach can be applied to mines that will implement the technology of the gob-side entry retaining formed by roof cut and pressure releasing, providing important references for the evaluation and optimization of its support design, and the determination of the dynamic pressure zone length.