Study On Prevention & Control Techology And Disaster-Caused Mechanism Of Bed Separation Water Body In Overburden Strata During Coal Seam Mining

As a new type of coal mine water hazard,bed separation water inrush caused great economic loss and casualties for many coal mines over the years.Due to the characteristics of bed separation water inrush,such as:burstiness,complex and random,there are great difficulties in prevention and treatment.Therefore,there are great theoretical significance and engineering application value to study the disaster-caused mechanism of bed separation water inrush and establish the scientific prevention and control technology system.In this paper,through the technological means of theoretical study,case analysis,numerical simulation,similar simulation and on-site verification,the disaster-caused mechanism of bed separation water inrush and prevention and control key technology were studied.The innovative results as follows:(1)Based on the case analysis of bed separation water inrush,the type of bed separation water inrush was classified.According to the mining mode and relative position between the disaster-caused water body of bed separation and water-conductive fracture zone,the bed separation water inrush was divided into 2kinds and 2 types.The typical characteristics of bed separation water inrush and three water inrush modes were established.(2)The bed separation in overburden strata was divided into general bed separation,water filling bed separation and disaster-caused bed separation.The development rule,water filling characteristics and disaster-caused mechanism of bed separation space were studied,and 3-level discriminant method was provided.(3)The water storage mechanism of bed separation kind1 type2 and kind2 type2were analyzed.The key mudstone aquiclude in water-conductive fracture zone and its thickness are the main control factors of 2 kinds bed separation water storage.A critical thickness analysis method based on the vertical seepage velocity distribution of the key mudstone aquiclude is proposed.(4)The bed separation water inrush mechanism of 1 kind 2type in 1121 working face of Hongliu coal mine and 2 kind 2type in 73003 working face of Laohutai coal mine were ascertained.The risk zoning of bed separation water inrush in coal field was studied,and the results were verified by engineering practice on site.(5)6 prevention and control technical measures of bed separation water inrush were put forward:pre-drainage of aquifer that filling to bed separation,cutting the strong runoff,pre-drainage of bed separation water with borehole on the ground or underground,accurate drainage during working face mining and optimization of mining technology,sequence,working face layout,working face mining speed.The prevention and control technology system of bed separation water inrush from overburden strata was established.(6)The water inflow law of bed separation water drainage based on 39 borehole was analyzed systematically in Hongliu coal mine.The experience formula of the bed separation water body center was established,and provides the target for precision drainage of bed separation water body.The optimal timing of drainage of bed separation water body was put forward:after formation of bed separation water body according to caving span and before breakage of mudstone aquiclude.The sarciniform boreholes underground were used to drain the bed separation water body and this key technological measure can be guarantee the safety mining of working face.After this technology application in Hongliu coal mine,1121 working face that bed separation water inrush happened four times(the maximum water flow was 3000m~3/h)was achieved safety mining.At present,eleven working faces were mined safety.