峁梁区浅埋采空区下开采顶板活化结构与支架动载研究

Activated roof structure and dynamic load of support under goaf of shallow-buried close coal seams in loess hilly area

为了揭示峁梁区浅埋采空区下开采支架动压机理,以陕北张家峁煤矿4^(-2)与5^(-2)浅埋近距离煤层开采为背景,采用现场实测、物理相似模拟、理论分析及工程实例验证相结合的方法,研究了顶板间隔岩层结构和采空区覆岩“活化结构”运动特征,分析了下煤层工作面在进出峁梁载荷影响阶段的支架动载及超前支承压力变化规律,建立了上覆“活化砌体梁”与间隔岩层“砌体梁-台阶岩梁”耦合结构力学模型,揭示了峁梁区浅埋采空区下采场支架动载机理,并得出了峁梁采空区下采场支架动载分区。研究表明:工作面在过峁梁载荷影响区动载最大,出峁梁载荷影响区后次之,进峁梁载荷影响区前最小。工作面在峁梁载荷影响区超前支承压力峰值较大,约为出峁梁载荷影响区后的1.12倍,为进峁梁载荷影响区前的1.61倍。通过建立进、出峁梁载荷影响区时的顶板耦合结构力学模型,揭示了峁梁区采空区下开采的支架动载主要源于上煤层垮落顶板“活化结构”与间隔岩层结构同步运动,使峁梁区载荷通过“活化结构”传递于间隔岩层结构,导致支架强烈动载。研究得出,工作面支架阻力的确定应当以峁梁区顶板结构同步运动的大周期来压载荷作为依据,并通过实例分析验证了支架动载计算公式的可靠性。

In order to reveal the mechanism of the dynamic load of support under the goaf of shallow coal face in loess hilly area,the mining of 4^(-2)and 5^(-2) shallow coal seams in Zhangjiamao Coal Mine in northern Shanxi is taken as the research background.With field measurement,physical simulation,theoretical anal-ysis and engineering verification,the movement characteristics of the interval strata roof structure and the'activated structure"on the upper seam goaf are studied.The variation of the support dynamic load and the front abutment pressure distribution of the lower coal seam working face are analyzed in the stage ofentering,passing and leaving the loess hilly area,with which the mechanical model of the coupling structureof the overlying"activated voussoir beam"and the interval strata"voussoir beam-step voussoirbeam"is established,the mechanism of the dynamic load on the support is revealed,and the dynamicload zoning of the support under the goaf in the loess hilly area is obtained.The research shows that whenwork face passes,leaves,enters the load influence area of the loess hilly,the dynamic load ranges fromthe largest to the smallest.The peak value of the front abutment pressure in the load influence area of loesshilly about 1.12 times and 16.1 times larger than that after and before leaving the load influence area ofthe loess hilly.By establishing the mechanical model of roof coupling structure when work face enteringand leaving the loess hilly load influence area,it is revealed that the dynamic load of the support of theunder goaf mining in the Maoliang area mainly comes from the synchronous movement of the"activatedstructure"of the upper coal seam caving roof and the interval strata structure,so that the load in the loesshilly area is transferred to the interval strata structure through the"activation structure",resulting in strongdynamic load of support.It is concluded that the support resistance of the working face should be based onthe long period weighting by the synchronous movement of the roof structure in the loess hilly area.Thereliability of the dynamic load calculation formula of the support is verified through practical analysis.