Prevention and control technology and application of roof water disaster in Jurassic coal field of Ordos Basin

In order to achieve a safe mining of coal resources under the threat of roof water disasters in Jurassic coal field of Ordos basin,based on the existence conditions of Jurassic coal resources,the characteristics of roof aquifers,the distritution range and prevention & control problem of water disaster from roof aquifer,the formation mechanism,iden- tification method,main control factors,prevention and control techniques of four typical roof water disasters (bed sepa- ration water disaster,water and sand inrush with thin bedrock,thick sandstone water disaster,and burnt stone water disaster) were studied systematically. In the Jurassic coal field,the geological condition for the bed separation water disaster is interlayer with sandstone and mudstone,the thickness of the water-proof mudstone is the main controlling factor. The precise positioning and drainage technology of bed separation water were researched and developed. The quantification of the identification and prevention & control technology of bed separation water disaster was developed. Water-sand fracture zone is the main controlling factor of water and sand inrush with thin bedrock. A risk evaluation system of water and sand inrush based on the relationship between water-sand fracture zone and bedrock thickness was constructed. The dfficient grouting technology of water-bearing loose sand body was invented,which effectively preven- ted the occurrence of water and sand inrush with thin bedrock. The haterogeneity of thick sandstone aquifer in vertical direction was discovered,and the progressive seepage water filling mode was revealed. A new concept of water disaster prevention and control of thick sandstone water disaster was put forward,which was “appropriately swept and actively controlled”. A large number of coal resources threatened by thick sandstone water disaster was liberated. The “bound- ary of burnt rock with abundant water” effect was revealed. The complete section of the burnt rock is divided into di- rect outcropping area,central burial area and burnting boundary area. The seletion criterion of grouting material for dif- ferent sections of burnt rock was constructed. The optimal drainage grouting curtain technique with double-positon bidi- rectional borehole sequence was put forward,which can significantly reduce the water supply to the working face from burnt rock and the water conservation can be realized with coal mining. Though the application of the prevention and control technology of roof water disaster to the Jurassic coal field in Ordos basin,the occurrence of roof water disaster has been restrained effectively,and the coal resources have been produced efficiently,safely and in a green way. At the same time,the theory and technology of mine water disaster prevetion and control have been greatly enriched.