Study On Safe Mining Technology Under Shallow-buried And Water-rich Zone

China is a country with rich coal,poor oil and less gas.Coal resources occupy the dominant position in China’s energy structure.The cornerstone of social stability and development depend on safety coal mining.The shallow buried coal seam in Northern Shaanxi has the characteristics of simple geological conditions,good coal quality,shallow buried coal seam,easy mining and low production cost,however,it’s easy to cause the disaster of the sand inrush and water blasting,causing heavy casualties and property losses.Therefore,the sand inrush and water blasting has become the focus of the majority of scholars.The sand inrush and water blasting is determined by the special geological environment,such as shallow buried depth,thin bedrock and thick and loose overburden which is rich in diving,affected by many factors,such as hydrogeology,engineering geology,coal seam,overlying strata and mining methods.This paper depend on characteristics of thin bedrock,shallow coal seam,water-rich and loose sand bed in three panel of 2^-2coal mining in Hanjiawan.The influencing factors of water inrush and sand bursting are analyzed and the mechanics analysis model of water inrush and sand disaster is established.On this basis,the prevention and control technology of sand inrush and water blasting disaster are put forward.The prevention and control technology,applied to the mining process in hanjiawan Coal Mine,has get a greet success in preventing the sand inrush and water blasting disaster,ensuring the safe production of the working face,achieving a good technical,economic and social effects.This paper mainly obtains the following results:（1）According to the engineering geological and hydrogeological conditions of the 2^-2coal in the three plate area,the influencing factors and mechanism of water inrush and sanderosion are analyzed.It is concluded that there must be four conditions for water inrush and sand bursting : plenty of saturated water-bearing sand layer;enough water-bearing sand channel;dynamic hydraulic pressure generated by the disturbance of the latent head pressure in the aquifer can able to make the sand granule move;enough room for water and sand.In the shallow-buried seam geological environment,when the roof thin bedrock fractured,dynamic hydraulic pressure reaches a critical value,it will cause a large number of mixed flow of sand and water into the roadway and goaf.（2）According to the computing height of“two-zone”,the average thickness of 2^-2coal seam is 4.4m.Theoretical calculation height of “two-zone” respectively shows that the height of caved zone is 13.29 m,the height of water flowing fractured zone is 46.95 m.It is expected that the development height of 2^-2 coal seam roof water flowing fractured zone will affect the overlying bedrock aquifer,and there may be sand inrush and water blasting disaster during the mining process.（3）Behind the supports,the tension cracks of main roof rock caused by flexural deformation totally direct the vertical direction,and the top of cracks is wide and below of it is narrow.Under the action of gravity,the formation of larger cracks along the depth of sliding and dislocation separation,fault offset is generally 0.7¹.5m,the direct sliding bedrock aquifer,the aquifer water will inevitably lead to collapse into the face,the local fractured wide area may lead to sand inrush and water blasting disaster.（4）Comprehensive prevention and control technology of water inrush and sand bursting is put forwarded.The formation conditions and influencing factors of comprehensive analysis of water inrush of sand are comprehensively analysised,according to the requirements of water prevention in Hanjiawan coal mining,designing project proposals for water prevention in water-rich area,including project layout,construction technology and safety measures.On this basis,the comprehensive plan of using mine water is designed,mine water disaster prevention measures are put forwarded,water and sand prevention emergency plan is formulate.