Optimization of construction parameters for drainage drilling under complex hydrogeological conditions
In light of the problem of drilling construction parameters for pre mining drainage of coal seams in composite wa-ter filled aquifers,numerical simulation analysis was used to study the efficiency and economy of drainage under different drilling angles,number of drilling holes,and spacing between drilling sites.The results show that the total water inflow of the borehole gradually decreases with the increase of the borehole elevation angle,and gradually increases with the increase of the number of boreholes.When the number of boreholes exceeds 5,the total water inflow of the borehole remains basically unchanged;When the elevation angle of the borehole is 60°,the maximum water inflow per unit length of borehole is a-chieved,and the more boreholes there are,the smaller the water inflow per unit length of borehole is;The optimal construction parameters for a single drilling site are:a vertical length of 120 m,a drilling elevation angle of 60°,and 5 drilling holes;Re-ducing the spacing between drilling sites can improve the efficiency of drainage,but it will also increase the construction cost of drilling and drainage.Therefore,it is recommended to increase the spacing between drilling sites when the construction peri-od is relatively ample,and to reduce the spacing between drilling sites when the construction period is relatively compact.
composite water filled aquifernumerical simulationborehole elevation anglenumber of boreholesdistance be-tween drilling siteswater inflowdrainage
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