大采高工作面覆岩空间结构变化矿压显现规律研究

Mining pressure variation induced by spatial structure change of overlying strata

为研究工作面回采过程中,在经历不同的采空边界条件下,工作面不同覆岩空间结构变化及对矿压显现的影响,基于理论计算、微震监测、应力在线监测等方法,对母杜柴登煤矿30202工作面回采期间所形成的不同覆岩结构类型进行分析,得到不同覆岩空间结构下强矿压显现特征及危险区分布规律。研究结果表明:30202工作面回采过程中,先后经历“一面为自身采空区,三面为实体煤”到“两面为采空区,两面为实体煤”的边界条件,其覆岩空间结构相应的会经历“O”型、“O-S”型到“S”型覆岩结构转换和稳定的过程。工作面在“一面采空”条件下,回采过程中发生强矿压的危险性较小;工作面在经历“一面采空”到“两面采空”边界条件转变过程中,其临近已采工作面采空区侧及其端头煤发生强矿压的危险性较上一阶段明显增加;在“两面采空”条件下,本工作面高位岩层与相邻采空区上覆未回转下沉的高位岩梁容易产生连动,形成高位、跨度大的岩梁失稳,使得30202工作面回风巷侧在叠加应力影响下容易发生强矿压。研究结果可为工作面在不同开采条件下采场矿压特征分析、顶板控制和巷道支护设计提供一定借鉴。

In order to study the spatial structure change of overlying strata and its influence on strong mine pressure under different mining boundary conditions, the types of overlying strata structures formed during 30202 working face mining of Muduchidan Coal Mine based on theoretical calculation, microseismic monitoring and on-line stress monitoring, and the strong mine pressure characteristics and distribution rules of hazard area are obtained under different spatial structures of overlying strata. The results show that during the mining of 30202 working face, it will experience the boundary conditions of “goaf on one side, and solid coal on three sides” to “goaf on two sides, and solid coal on two sides”, its spatial structure of overlying strata will experience the process of “O” type, “O-S” type to “S” type. Under the condition of “one side goaf”, the risk of strong mine pressure in the mining process is small;when the boundary conditions changes from “one side goaf” to “two sides goaf”, the strong mine pressure risk of the goaf side and its end coal in the adjacent working face is obviously higher than that in the previous stage;under the condition of “two sides goaf”, the high-level rock formation and the overlying high-level rock beam that has not been rotated and sunk in the adjacent goaf are prone to interlock, resulting in instability of the high-level and large-span rock beam, which may lead to strong mine pressure in the side air return way of the 30202 working face under the superimposed stress. The research results can be used for reference for the analysis of stope pressure characteristics, roof control and roadway support design under different mining conditions.