Study On The Control Of Thick And Hard Sandstone Roof Above Fully Mechanized Working Face

According to the thick and hard roof geological conditions in210108working face, theoretical analysis, numerical simulation and field practice methods are used to study roof breaking laws.The main study of this paper includes several accepts blow:(1)Thick and hard roof mechanic model is adjust to the plate mechanic model.Establish the plate mechanic model,and use the mathematical and mechanical analysis method,give the theoretical solution of first caving and periodic caving.(2)Deep hole blasting mainly effect by the blasting hole depth and hole diameter,hole angle and the hole height. Under the condition of high stress,it is harder to blast the rock,by change the four main parameters,we can get the needed blasting effect.(3)Different blasting parameters will lead to the rules of stress distribution different in thick and hard roof-The numerical simulation results show that when the blasting height is lower,due to blasting hole cross the thick and hard roof,the first breaking step and periodic breaking step will be shorter,and the pressure will less.So the major effect of blasting is the destruction of key strata.(4)By comparing the analysis of field measured data with the result of numerical simulation, it is found that advanced blasting can effectively reduce pressure interval and weaken the ground pressure. the result of numerical simulation can reflect the basic roof breakage.lt decreases the size of rock broken,and it eliminates the phenomenon of dynamic impact when the size of rock broken,and it eliminated the phenomenon of dynamic impact when the ruptured of thick and hard roof.Research results can provide important references, theoretical and engineering basis on the mining safety working and roof control.