浅埋近距离煤层工作面过末采煤柱覆岩结构及动载传递规律研究

Research on strata structure and dynamic load transfer of under coal pillars of last mining section in shallow and close coal seams

为了揭示浅埋近距离煤层工作面过末采两段煤柱的应力传递规律和来压机理,以神东某矿12101工作面为工程背景,采用物理相似模拟、数值计算及理论分析相结合的方法,研究了工作面过回撤通道及两段煤柱的覆岩结构、来压规律和超前支承压力演化规律,揭示了煤柱应力传递规律与支架动载机理。研究表明:过1段煤柱开采的超前支承压力最大,出2段煤柱的支架载荷最大;出各煤柱阶段(过空巷)应力传递最大,煤柱中阶段次之,进煤柱阶段最小。煤柱传递的集中应力由工作面超前煤壁和支架上方顶板结构共同承担,煤柱传递的载荷从进煤柱阶段以超前煤壁承担为主,逐步转换为出煤柱阶段以支架承担为主,煤柱集中应力向工作面顶板结构转移是导致支架动载的主要原因。煤柱向底板传递的垂直应力作用于下煤层顶板关键块,导致顶板结构切落失稳,形成强烈来压显现。研究结果与现场实测结果吻合,可为类似条件下工作面的开采提供借鉴。

In order to reveal the stress transfer and roof weighting mechanism of mining under two coal pillars of last mining in shallow and close coal seams,this research takes the 12101 coal face of a coal mine in Shendong mining area as the engineering background,studies the overburden structure of mining under two pillars with two withdrawal channel by the methods of physical simulation,numerical calculation and theoretical analysis.The stress transfer of coal pillars and the dynamic load mechanism of support are revealed.The research shows that the advanced abutment pressure and support load in the stage of under pillar mining are greater than under the goaf mining,and the support load reaches the peak in the outward pillar stage.The stress transfer is the largest in the outward pillar stage,the second in the under pillar stage and the smallest in the inward pillar stage.The concentrated stress transmitted by the pillar is shared by the leading coal wall of the mining face and the roof structure above the support.The load transmitted by the coal pillar is mainly borne by the leading coal wall from the inward pillar stage to the supports of the mining face in the outward pillar stage.The transfer of the pillar stress to the roof structure of the working face is the main reason for the dynamic load of the support.The vertical stress transmitted from the pillar floor to the key blocks of the lower coal face roof structure,results in the roof structure instability and induces strong roof weighting.This research is consistent with the field measurement,which provides a reference for mining under similar conditions.