242 / 2018-05-06 06:33:10

Surrounding Rock Deformation Characteristics of Retreating Roadways and the Control Technique for Extra-thick Coal Seams under Fully-mechanized Top Caving and Intensive Mining Conditions--- A Case Stu

extra-thick coal seam; retreating roadway; single mechanical props with constant resistance; similar material simulation; deformation characteristics.

矿山动力灾害 > 顶板

For most of retreating roadways in extra-thick coal seams affected by multiple mining activities under fully-mechanized top caving mining conditions, surrounding rock deformation and stress evolution of the roadways are complex under intensive mining due to tonstein occurrence in top thick coal roof, developed fissures and fractures in coal seams, and large cross-section of the roadways; if no appropriate support techniques and optimization measures were taken under such mining conditions, the consequences, including severe bedding separation, large deformation of surrounding rock, and large-area top caving disaster, would frequently result. Therefore, investigation of surrounding rock deformation characteristics of retreating roadways and the control technique for extra-thick coal seams under fully-mechanized top caving and intensive mining conditions is the key of stability control for this type of roadways. Multiply research methods were adopted comprehensively in this study, such as field investigation, monitoring and statistics, experimental tests, theoretical analysis, similar material simulation, and field tests. Taking the classic area of the return airway # 5110 in the main mining coal seam # 3-5 with the thickness of 14.7 m of Tashan coal mine, Datong Coal Mine Group as the research object, failure characteristics of roof supporting structures of the return airway # 5110 undergoing retreating mining of the upper coal panel # 8109 and the current mining panel # 8110 were investigated. By employing bedding separation acquisition monitoring device and force-meters, surrounding rock deformation, carrying load of rock bolts and cables, and bedding separation were monitored and analyzed, by which the surrounding rock deformation and loading characteristics of the supporting structures in the roadway # 5110 were obtained under intensive mining condition for the extra-thick coal seam. Stress evolution during the process from roadway stability to instability was characterized experimentally under different side pressure conditions by using similar material simulation. On the basis, single mechanical props with constant resistance was proposed to support surrounding rock of retreating roadways in extra-thick coal seams. It was analyzed on the structure and working mechanisms of the prop set, its working resistance under the height of 3m, support patterns, and support techniques, and then field tests were conducted in the retreating roadway # 5110. The results showed that the maximum bedding separation far away from the roadway in the trial area is 83mm, and that near the roadway is 56mm. From the test results, it can be known that good control effect on surrounding rock deformation and roof support can be achieved. The study can be applied for the entire Tashan coal mine, and has significant implication for engineering projects with similar geological and mining conditions.