Evolution Of The Roof Force Chain And Destruction Rule Of Top-coal Research In Fully Mechanized Caving Stope

This paper using photoelastic mechanics and numerical simulation and theoretical analysis of comprehensive research methods,from the meso-scale carried out in fully mechanized top coal caving stope roof force chain evolution rules and force chain evolution on the failure rules of top coal study.The research shows that with the advancing of the working face,a point in the roof of the evolution of force chain direction is vertical-inclined-horizontal-inclined-vertical and force chain to gather around the stope to form multi-storey force chain bundle of arch,the outermost force chain bundle of arch bearing the above all stratum weight,it is main bearing force system of stope and the main force source to cause the damage of coal and rock mass,which is the same as the mechanical characteristics of stress shell,the other layers are located below it and main carrying top caving rock weight.Roof lithology has significant influence on evolution of force chain,hardness roof is easy to form carrying heavy chains and maintaining the mechanical behavior of lateral force transmission.Roof force chain has an important influence on the top coal destruction,the internal force chain of top coal is destroyed and the balance of force chain is broken under the action of roof force chain,leading to the internal force chain network structure of top coal is destroyed and roof coal caving.The results of this study provide a new method for further revealing the spatial structure evolution of overlying strata under the condition of fully mechanized caving mining with high strength and discussion on the safety control of the disaster caused by the instability of overlying strata in the fully mechanized caving mining,has a certain practical significance to the safe and efficient production of thick coal seam in our country.