Occurrence Characteristics And Construction Hazards Of Hydrogen Sulfide Gas In Yuelongmen Tunnel Of Chengdu To Lanzhou Railway

ChengLan railway from Chengdu,through Guanghan,Shifang,Maoxian and Jiuzhaigou,ultimately reached the city of Lanzhou,a total length of 727 km,passenger and freight lines,belonging to the national railway I double electrified fast railway.The YueLongMen tunnel is a key project of Cheng Lan railway,which is connected with the former station of Gochuan,the second is the bridge of the sheep,and the double line is adopted,the maximum line spacing is 60m,the minimum line spacing is 30m.InDecember 20,2014,at the construction process of the YueLongMen tunnel,construction workers feel dizzy,nausea,and discomfort of nose,eyes,throat.After identification,there is hydrogen sulfide gas in YueLongMen tunnel.According to the current "coal mine safety regulations",the maximum allowable concentration of hydrogen sulfide in the air is 6.6ppm,referring to this standard,jump Longmen tunnel hydrogen sulfide emissions seriously exceeded.If we do not respond in time,it will have a great impact on the safety of tunnel construction,the construction schedule and the later operation.Based on this situation,this paper analyze the hydrogen sulfide gasbased on field reconnaissance,indoor test and methods of regional geological survey of yue longmen tunnel of hydrogen sulfide gas occurrence characteristics are analyzed.Research shows that in the special lithology,special metal ore belt,abnormal regional fold fracture combined conditions,hydrogen sulfide sulfur formation material in case of thermochemical sulfate reduction,and upward flowing water,dissolved in water,with the groundwater migration,after excavation of the tunnel,because of surrounding rock and groundwater field disturbed,breaking the original balance ring hydrogen sulfide existence and sulfide hydrolysis,hydrogen sulfide will gush.After the tunnel ventilation,the hydrogen sulfide concentration in the tunnel is obviously reduced,and the concentration of hydrogen sulfide gas in the wind direction of the return air lane is obviously higher than that of the upper wind direction.