Study On Surrounding Rock Deformation Mechanism And Reinforcement Technique Of Lower Coal Seam Roadway In Zhaiyadi Coal Mine

Coal mining causes stress redistribution of surrounding rock around the stope. Increased stress zone emerges in front and back side of mining area, coal body of both sides and pillars. Reduced stress zone emerges in the edge. Make full use of the distribution law of surrounding rock stress caused by mining, the roadway in Lower coal seam is arranged in reduced stress zone below goaf. But the different relationship between position and mining time of roadway causes stress variation and different deformation of surrounding rock. When roadway in Lower coal seam is near to working face in the upper slice, face mined and stress concentration of section pillar lead to a sharp adjustment of stress in the side of pillar goaf.In this paper, based on the problem of stratified roadway instability in Zhaiyadi colliery, theoretical analysis, numerical simulation, field investigation and industrial tests are used to analyze the stability characteristics of lower stratified roadway affected by upper mining action, the reason of roadway destruction is analyzed, a reliable reinforcement technology is proposed. The key elements as follow:(1) Instability mechanism: Theoretical calculation, numerical simulation and field measurement are used to analyze the destruction reason of 3905 tailgate in lower layer. The fundamental reason of gateroad instability in lower layer is that the face mining in upper layer causes the relative change of horizontal stress much bigger than that of vertical stress below goaf around the pillar. The entire gateroad withstands greater horizontal stress, which causes the severe shear failure in roof and floor.(2) Reinforcement technique: a technique of "large-diameter prestressed cable and single prop auxiliary support" is proposed to control roadway shear failure caused by too large horizontal stress in the mining process. Prestressed cable effectively make original roadway roof maintain integrity, play a role in original support system to prevent the bolt and cable breakage chain reaction. Single prop auxiliary support can effectively deal with the sharp stress adjustment of roof in mining process. "Prestressed anchor and single prop auxiliary support" fundamentally control roadway deformation and failure, ensure the safety of roadway roof.(3) Industry practice: a reinforcement technique of lower stratified roadway in Zhaiyadi colliery affected by upper face mining and stress concentration of coal pillar is proposed and successful applied in industrial test.In short, a reinforcement technique of "large-diameter prestressed cable and single prop auxiliary support" is applied in lower stratified roadway of Zhaiyadi colliery. It effectively controls the deformation of surrounding rock and gets good supporting effect.