Study On The Mining Action Law Of Fault Coal Seam Group

According to geological conditions of coal face 111013 in a coal mine in Guizhou,studies the evolution law near roof fault of overburden rock fracture,stress and displacement in mining excavation by theoretical analysis,similar simulation experiment,numerical modeling experiment and field measurement.Exploring resistance of hydraulic support and rib spalling of the mechanism of the mine pressure behavior when coal face crossing the roof fault,which provide the theoretical basis of stability analysis of roof strata for the similar condition of coal face crossing fault zone.Using the mohr-coulomb theory and fracture mechanics theory,Analyzing the fault derived joint occurres extension and the failure law of fault by mining excavation.Using similar simulation experiment system,simulating the process of coal face mining,the height of caving zone and fractured zone is close to the value of empirical formula in none fault zone.When coal face near the roof fault,analyzing the condition of stress and displacement changes in the roof fault plane,getting the law of overburden rock fracture and the height of caving zone and fractured zone.The results show that,normal stress and shear stress reach maximum when coal face at roof fault;the height of caving zone and fractured zone affected highly by roof fault.Using FLAC3 D numerical simulation software,simulating the coal face in the process of step by step excavation.Analyzing the impact of advanced support pressure by roof fault,the law of stress in fault plane and overburden strata,the characteristics of plastic failure in overburden strata.The results show that,shear stress of fault ends is more significant than normal stress,so the rapidly increasing of shear stress is the main cause of fault activation;The top and bottom of fault affected differently in mining excavation,the bottom of fault affected delayed than the top.Using field measurement,getting resistance of hydraulic support and rib spalling,according to the position relations of roof fault and working face,mining process can be divided into non fault zone and fault zone,fault zone is divided into high and low pressure zone,rib spalling is significant in former and caving interval is much smaller than non fault zone.