薄层状顶板煤巷掘进迎头矿压显现规律与空顶区顶板失稳机理

Law of the Rock Pressure Behavior of Tunneling Head and Roof Instability Mechanism of the Empty Roof Area in the Coal Roadway with Thin Bedded Roof

煤巷工程巨大消耗量是由我国煤炭赋存特征及其开采体系决定的,煤巷掘进施工参数选取不合理易增加掘进作业处(掘进迎头附近)冒顶风险并降低成巷速度。为了解决煤巷掘进过程中普遍存在的“安全与高效难统一”问题,综合采用理论分析、数值模拟和现场试验等方法,系统研究了矩形断面薄层状顶板煤巷掘进迎头附近围岩的矿压显现规律,揭示了掘进迎头空顶区顶板的变形特征与失稳机理。研究结果表明,煤巷掘进影响下顶板应力、变形与破坏均始动于掘进迎头前方一定距离,且均具有渐次演化特征;空顶区下位薄层岩板挠曲具有非对称性,拉伸和剪切作用是导致其破坏的根源,下位岩层破坏将引起若干层薄层岩板自下而上逐层破坏;以下位薄层岩板抗拉强度不超过其内力作为判据,可确定出特定工程地质条件下煤巷掘进的极限空顶距。基于确定的极限空顶距,结合赵庄矿53152回风巷工程地质条件和原支护方案,优化了支护方案和施工工序,工程实践现场统计与监测结果表明:在确保煤巷综掘期间施工安全与掘后顶板稳定的同时,成巷速度提高了25%左右。

The huge consumption of coal roadway is determined by the coal occurrence characteristics and the mining system in our country,the unreasonable selection of construction parameters of coal roadway is easy to increase the risk of roof falling and reduce the speed of roadway formation in the tunneling operation site(near the tunneling head).In order to solve the problem that safety and efficiency are difficult to be unified in the process of coal roadway tunneling,the rock pressure behavior laws of surrounding rock near the tunneling head in the rectangular section in coal roadway with thin bedded roof was systematically researched by means of theoretical analysis,numerical simulation and field tests,and the deformation characteristics and instability mechanism of the roof in the empty roof area at the tunneling head were revealed.The research results show that the stress,deformation and failure of the roof under the influence of coal roadway tunneling all start at a certain distance in front of the tunneling head,and all have the characteristics of gradual evolution.The bending of the lower thin rock plate in the empty roof area is asymmetric,and the tensile and shear actions are the root causes of its failure,the failure of the underlying rock plate would cause the failure of several thin rock plates from bottom to top.The criterion that the tensile strength of the lower thin rock plate doesn’t exceed its internal force could determine the limit empty roof distance of coal roadway tunneling under specific engineering geological conditions.Based on the determined limit empty roof distance,combined with the engineering geological conditions and original support scheme of 53152return airway in Zhaozhuang Mine,the support scheme and construction process were optimized,and the field practice was carried out.The field statistics and monitoring results show that the speed of roadway formation is increased by about 25%while ensuring the construction safety during the comprehensive excavation of coal roadway and the roof stability after excavation.