Abstract
This article focuses on the energy density alteration during non-pillar mining method of goaf-side entry retaining by roof cutting (GERRC) and adjacent working face mining. We also studied the support control strategy of goaf-side roadway. Numerical calculation model is established, and the parameters of the model are verified by the measured advance abutment pressure and numerical solution. Based on the numerical model, the energy density during mining is studied. It is found that the whole energy evolution pattern of the goaf side entry during the two adjacent working face mining includes: the original rock energy, the advance energy of the current working face, the dynamic lateral abutment energy caused by strata movement, the lateral abutment energy of the adjacent working face. The support body failure and surrounding rock large deformation phenomenon often occur in goaf side roadway, which is influenced by multiple energy disturbances. Research shows that strong stress disturbance of surrounding rock generates in front of the working face 23 m and behind of working face 60 m in GERRC method. In the second goaf-side entry retaining, the range is in front of the working face 47 m. The evolution law of energy field puts forward the strategy of using the high constant resistance and large deformation (CRLD) anchor cable and procured preferable effect.
Highlights
The goaf-side entry retaining by roof cutting (GERRC) technology can avoid the waste of coal resources and save the cost of tunnel driving [1]
Compared with the traditional coal mining method, no pillar mining has significant technical and economic advantages, such as: (1) the existence of the traditional coal pillar is eliminated, and the recovery rate of resources is improved; (2) it solves the problems of stress concentration caused by coal pillars; (3) the driving cost can be reduced and eliminate the existence of isolated island working face
Their research obtained the following conclusions: goaf-side entry retaining is in the area of stress decreasing zone; the impact scope and range to the rock becomes more wide with the increase of mining height of working face; the optimal cross-height ratio and the high pre-stress supporting system could be helpful to control the deformation of surrounding rock
Summary
The goaf-side entry retaining by roof cutting (GERRC) technology can avoid the waste of coal resources and save the cost of tunnel driving [1]. This method is expected to be better applied and improved in China [2]. Their research obtained the following conclusions: goaf-side entry retaining is in the area of stress decreasing zone; the impact scope and range to the rock becomes more wide with the increase of mining height of working face; the optimal cross-height ratio and the high pre-stress supporting system could be helpful to control the deformation of surrounding rock. In the area of strong stress disturbance, the deformation of surrounding rock is controlled by the joint action of single hydraulic prop and anchor cable
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