Study On The Prediction Technology Of Gas Outburst Risk Of Baoding No.2 Tunnel

Taking Baoding No.2 tunnel of panzhihua-dali expressway(sichuan province)project as the engineering background,this paper uses complex geological conditions such as solid coal,fault structural belt and goaf in the coal-bearing strata of the Triassic Datundi Formation.Methods such as analysis,simulation,experiment and investigation have studied the danger of tunnel outburst.On the basis of the current "iron regulations",the progressive prediction technology adapted to highway tunnels is proposed.At the same time,the high-pressure hydraulic slitting and anti-reflection technology was introduced as the key technology for tunnel crossing through the outburst coal seam disaster control.The numerical simulation was used to compare and analyze the pumping effect,and the technology was used in practice,and achieved good application results.The main results are as follows:(1)Based on the current "iron regulations",the prediction of the dangerous risk of the area plus the working surface with wider prediction and higher precision is proposed,and the progressive anti-explosion prediction technology suitable for highway tunnels is formed.(2)Determined that the reasonable risk prediction of the Baoding No.2 tunnel area is 11m;(3)The method of “regional prediction adopts gas content w,working surface prediction adopts gas content w combined with drill cuttings gas desorption index k1 value” is proposed;(4)Determine the reasonable control range and effective arrangement of the predicted drilling of the area and working face under the three different geological conditions of Baoding No.2 tunnel through solid coal,fault structural belt and goaf;(5)High-pressure hydraulic slitting technical measures can effectively reduce coal body stress,increase gas permeability,improve drainage efficiency,and ensure rapid and safe tunneling of tunnels.