Preliminary study on the water prevention and control engineering technology of coal uncovering in rock roadway of water-rich coal seam of Balasu mine field

Coal seams are mostly dense sediments, which are generally regarded as aquiclude.In recent years, the problem of water rich coal seams found in Yuhengbei area of Jurassic coalfield in northern Shaanxi is more prominent.In order to solve the hidden danger of No.2 water-rich coal seam water hazards during the rock roadway uphill tunneling in northern Yuheng mining area, taking Balasu coal mine as an example, the principle of "geophysical exploration first, drilling later" and the comprehensive means of dynamic monitoring, hydrochemical analysis, borehole peeping are employed in the process of rock roadway tunneling to ensure the safety of uncovering coal.The abnormal water-rich area in No.2 coal seam ahead of roadway tunneling is found through the geophysical exploration, and then the significant drainage effect of drilling engineering is proved.Based on that, the coal seam water quality type is confirmed as SO₄^2--Na·(Ca), and the total salinity is confirmed as around 6 000 mg/L through the hydrochemical analysis.Peaking through the drilling, the cracks developed in the coal seam and the connected water are revealed.Thus, the main characteristics of the No.2 coal seam water in this area are large occurrence range, poor supply conditions, good hydraulic connection and mainly static reserves.The long-time closed state is conducive to the development of mine drainage work.The safety experience of uncovering coal can be used for reference in later mining roadway uncovering coal.