Study On Influence Law Of Dynamic Strata Pressure In The Shallow Coal Seams Face Under Hilly And Gully Terrain

Gully terrain in shallow coal seam is ubiquitous in the western mine areas of china,For example, Shendong mine area locates in the junction of Shanxi and Inner Mongolia, itscoal seam is shallow and nearly flat, and the fall between peak and dip of certain gullyslope reaches30to70meters, further more, not only loose topsoil layer in the valley butalso some bed rock do not exist due to erosion. There were many dynamic strata pressureaccidents when the working face in Huojitu coal mine of Shendong mine area crossedgully terrain, such as sharp shrinking of active column of powered support and supportscrushing, which is a serious threat to mine safety and efficient production. In order toaddress the above problems, this dissertation has deeply researched about the law of theinfluence of valley terrain on the dynamic strata pressure of working faces in shallowseam.By the use of measurements, theoretical analysis, physical simulation and numericalsimulation, the following content is studied:(1) characteristics and generation mechanism of the dynamic strata pressure ofworking faces in shallow seam when crossing gully terrain;(2) influence laws of topographical features of the gully terrain (gully deep, slopeangle, position of the erosion of the primary key strata, angle of gully towards the directionof projection and face advance) on generating dynamic strata pressure when working facesin shallow seam crossing gully terrain;(3) influence law of the layer's distance on the dynamic strata pressure of repeated miningworking face in shallow seam when crossing gully terrain;(4) prevention countermeasures of dynamic strata pressure of working faces in shallow seamwhen crossing gully terrainThe major innovation achievements are as follows:(1) The dissertation has revealed that the characteristics and generation mechanism of thedynamic strata pressure of working faces in shallow seam when crossing gully terrain; The dynamicstrata behaviors is prone to appear during uphill of gully terrain, and the primary reason that thedynamic strata pressure appeared when working faces advancing is loss of primary key stratum.(2) Influence factors of producing dynamic strata pressure when working face is crossinggully terrain are mastered;(3) The dissertation has proposed prevention and treatment measures of dynamic stratapressure working face in shallow seam under gully terrain.The research result has served as guidance for prevention of dynamic strata behaviors whencrossing gully terrain in working face21305and21306of panel3in Huojitu mine as well asworking face22303in Bulianta mine, and has achieved good effects.