Numerical Simulation Study On The Relationship Between The Law Of Overlying Strata And The Emergence Of Roof Water In Shallow Coal Seam

Mine water hazard is a major safety problem in China's coal mines,and it is also a difficult problem to solve for a long time.The problem of roof water disaster in shallow seam has gradually become one of the main hazards affecting mine safety production.During the development of Yushen coalfield in northern Shaanxi,there have been many serious accidents of water gushing and sand bursting in mines,which have resulted in several mine stoppages,mechanical equipment scrapping and serious economic losses.Therefore,in order to ensure the safety of coal mine production,the paper studies the treatment of roof water hazards in shallow coal mines.Taking the 93101 first mining face of Jinjie Coal Mine 1 panel as the research background,this paper simulates and studies the overlying strata activity law of shallow coal seam,the influence of different mining width on the development height of water-conducting fracture zone,the relationship between overlying strata activity law and roof water gushing.The results show that the initial failure step of direct roof is not more than 8 m,and the ratio of guide to mining is 8.3 when the primary roof caving occurs,and the basic roof occurs.When the second periodic collapse occurs,the water conduction fracture zone develops the most,and the ratio of water conduction to production is 35.When the mining width is between 80 m and 180 m,the height of water-conducting fracture zone increases stepwise with the increase of mining width,and the roof failure distributes horizontally.When the mining width is greater than 180 m,the water-conducting fracture zone develops completely,and the roof failure characteristic is "saddle-shaped",then it is not affected by mining width.The critical threshold of mining width is 180 m,and the ratio of conductivity to mining is 35.1.Based on the above results,a method of forecasting and calculating the water inflow of working face by the combination of dynamic and static water is put forward.The seepage time of groundwater in Jinjie coal mine is determined to be 2 days,and the final time of water burst is 2 days.The research results are applied to the prediction and calculation of actual roof water inflow.According to the mine hydrogeological data,the predicted water inflow is close to the actual water inflow.The calculation method for predicting the water inflow of working face under the condition of water-rich mining in shallow seam provides a basis for the design of mine drainage system and the evaluation of drainage capacity,and provides a reference for the prevention and control of roof water inflow under similar conditions.