1. School of Resource and Safety Engineering,China University of Mining and Technology(Beijing),Beijing　 100083,China; 2. Coal Mining Branch,China Coal Research Institute,Beijing　 100013,China; 3. Mining & Designing Department,Tiandi Science & Technology Co. ,Ltd. ,Beijing　 100013,China

以山西余吾煤业N2105工作面回采过程中临空留巷底板冲击地压为工程背景,理论分析底板冲击地压可能的冲击启动区及主导应力源,采用数值模拟追踪煤层开挖后侧向煤柱及留巷围岩各向应力、位移的演化过程,建立采空区影响下留巷底板水平应力演化模型并进行验证。基于临空留巷底板冲击地压主导力源判定及能量传递过程分析,提出该类底板冲击地压分步防治关键技术,并进行现场应用。结果表明:煤层开挖后中,临空留巷底板在破坏深度范围内存在“卸压通道”机制,临空煤柱垂直应力不断增长的同时,留巷底板水平应力通过“卸压通道”释放,释放程度与该通道宽度呈正相关。临空煤柱帮内弹性核区为留巷底板冲击地压的冲击启动区,其不断增长的垂直应力为主导载荷源,而非留巷底板水平应力。为阻止该类底板冲击地压发生启动,关键在于削弱采空区侧向顶板压力传递作用及煤柱弹性能积聚水平,弱化留巷底板只能缓和冲击显现强度,非对称支护对留巷围岩变形破坏特征的适应性更强。

Entry floor usually suffers the greatest damage after floor rockburst. But the start-up area is not neces-sarily located within the floor. Based on the floor rockburst occurred at retained entry behind working face in a coal mine in Shanxi Province,the time and space sequences of rock burst associated with their corresponding relationship were ana- lyzed,and then the possible start-up area was pointed out. Numerical simulation code FLAC was utilized to analyze the load evolution law for the retained entry,and the “ relief channel” model within the floor was established. Based on field data,the key parameters for stepwise control technology for rockburst were determined,and on-site applications was carried out. The results showed that:“ relief channel” mechanism occurred within retained entry floor among the range of failure depth after the lateral coal was mined-out. The vertical stress in pillar increased,while the horizontal stress in the retained entry floor released through “ relief channel”. And the decline extent was positively correlated with the channel width. The elastic core area within pillar was start-up area for floor rockburst,and its increasing vertical stress was the leading load source. Due to the low strength of the floor,it became the main area where vibration en- ergy transformed to the crack surface energy and kinetic energy. In order to prevent start-up and mitigate the extent of damage of rockburst,the stepwise control technology was utilized,including the advanced pre-split within the hard roof,drilling within start-up area,setting drilling within cache corner to buffer shock,and non-asymmetric support at retained entry. After the application of technology above,the rock burst was successfully contained.

WANG Shuwen,JU Wenjun,PAN Junfeng. Determination on start-up area for floor rockburst at retained entry and its stepwise control tech- nology[J]. Journal of China Coal Society,2017,42(11):2799-2807.