The Law Of Ground Collapse And The Prediction Of Water Bursting Risk In Zhangjiamao Coal Mine

The main factor affecting the mine water inflow is the water diversion fracture zone caused by the overburden damage of the shallow coal seam.The water diversion fracture zone through the surface will cause the gully water or flood to break into the mine along the surface mining fracture and form the mine water disaster.In order to study the law of disturbance and damage,the characteristics of fracture development and the danger of water break of overlying strata when mining through the ditch in shallow coal seam,the study area is zhangjiarmao coal mine,Yushen mining area,which is located in the working face section of laolaigou.This study is not only of great application value to the prevention and control of water disaster in the shallow seam of zhangjiamao coal mine,but also of certain reference value to the prevention and control of water disaster in similar mines.Based on the comprehensive analysis of the previous data,the paper systematically summarizes the geological and hydrogeological conditions of zhangjiamao mine field.Through the combination of similar material simulation,numerical simulation and field exploration,the failure law of overburden and the development characteristics of surface fractures during coal mining are studied.The results show that:in the process of coal mining,the roof overburden will be accompanied by the vertical fractures of interlayer separation and rock cutting.The dynamic development law of the cracks is:the width of the slope cracks changes from small to large and tends to be stable with the excavation,the width of the slope foot cracks changes from small to large,then to small to closed,and the width of the cracks at the bottom of the ditch changes from small to large and then to small.This evolution law of surface fractures is mainly related to the topography and surface stress state:in the shoulder and upper part of the slope,the influence width of the mining fractures formed by the slope tensile stress increases;the influence width of the mining fractures formed by the slope foot by the slope foot pressure stress decreases or even closes;the compression stress and the slope rock compaction adjustment width decrease after the mining fractures formed at the ditch bottom.According to the drilling data of the working face,calculate the height of the 4-2 coal water diversion fracture zone,and draw the forecast map of the safety zone of laolaigou caving based on the difference between the terrain contour of the research area and the contour of the coal seam roof.The 14212 working face is in the conduction zone of the lower section of the caving fracture zone,and the 14213 working face is in the conduction zone of the upper section of the caving fracture zone.Based on the field investigation results of surface cracks,the crack width and number of laolaigou and its branches are predicted.According to the flood volume and water break volume under different fracture width conditions,the water break volume prediction experiment of channel water is carried out,and the calculation formula of water break volume under the experimental conditions is fitted out,and the actual water break volume prediction is carried out according to the geometric ratio determined by the fracture length.Combining the prediction results of water bursting quantity and the results of fracture safety zoning with the drainage capacity of the mine,the risk of water bursting is divided into two working faces of laolaigou mining.Finally,it is determined that the risk of water bursting of 14212 working face is small in non flood period,medium in flood period,medium in non flood period,and medium in non flood period The flood season belongs to the danger area of water break.