Research On Evolution Characteristics Of Activation Stress In Deep Fault Mining And Reasonable Setting Of Waterproof Coal Pillar In Zhaolou Coal Mine

Zhaolou Coal Mine is mainly mining No.3_up coal seam and No.3 coal seam.The mining depth is more than 800 m.The fault structure is developed in the field.The Ordovician limestone aquifer in the coal seam basement is widely distributed,thick,high water pressure and large difference in water abundance.After deep mining,the mine pressure,fault tectonic stress and supporting water pressure are in a high situation,and the risk of fault activation water inrush is high.At present,Zhaolou Coal Mine only set up coal pillars according to the corresponding data for faults with a drop greater than 30 m,and it is difficult to scientifically and rigorously ensure the safe production of the mine.In this paper,taking the fault waterproof pillar left in No.3 coal seam of Zhaolou Coal Mine as the engineering background,the fault activation mechanical model was established and analyzed by combining theoretical analysis,similar material simulation and Flac3D numerical simulation.Combined with the actual situation of Zhaolou Coal Mine,the risk of fault water inrush was judged,and the hydrological and engineering geological characteristics of FZ18-1 fault were evaluated.The overburden migration characteristics and stress evolution characteristics in the process of coal seam mining approaching the fault to its activation are deeply studied,and the width of fault waterproof coal pillar is preliminarily determined according to the limit distance of fault activation.Combined with the actual geological conditions of Zhaolou Coal Mine,the theoretical formula of waterproof coal pillar is analyzed and the width of coal pillar is calculated.The optimum width of waterproof coal pillar is determined comprehensively.The above research results are verified by field engineering implementation.The results show that the water content and conductivity of FZ18-1 fault are poor,but fault activation may exist.With the continuous advancement of coal seam,cracking occurs in the fault zone.The displacement of coal mining plate is larger and the displacement difference between the two plates continues to increase.In the same fault interface,the displacement of near coal seam is smaller than that of far coal seam.The vertical stress of the upper plate of the fault is slightly higher than that of the lower plate of the fault,and the stress concentration area is formed in front of the work.The stress concentration area gradually affects the fault area.Due to the barrier effect of the fault,the peak stress and the influence range of the coal pillar are increasing.Similar simulation and numerical simulation determine that the coal pillar sizes are 30 m and 50 m,respectively.The calculation results of the formula are 89.99 m and 99.04 m,and finally the width of the fault waterproof coal pillar is 100 m.Field engineering practice has realized the safe mining of working face,and the application and promotion of research results have provided support for the safe and sustainable development of mines under similar conditions.