Wen Ma Expressway Tunnel Phyllite Slate Gas Overflow Mechanism And Prediction Research

Gas disaster is one of the major hazards of tunnel construction,this paper takes Wenchuan to Barkam Expressway Zhegushan tunnel as the main object of study,investigation and analysis of relevant information,to carry out the tunnel engineering geological conditions of the partridge,the tunnel gas formation,overflow mechanism,prediction,prevention and monitoring of gas comprehensive research.The gas generated in the carbonaceous phyllite,slate source rock strata,tectonic fissures exist in the core of anticline,cover for phyllite,slate,Zhegushan tunnel for non coal gas tunnel with qualitative.In view of the tunnel structure,surrounding rock integrity,gas concentration have obvious difference,that is more close to the carbonaceous phyllite stratum,the gas concentration is higher;tectonic activity is more intense,more broken rock mass,the higher the concentration of gas.Phyllite stratum,has the advantages of high pressure,random distribution,stable gas emission sources.Mainly to crack free gas emission mainly non phyllite stratum gas,is characterized by low pressure,small flow,uneven distribution,emission is random.The gas surrounding Zhegushan tunnel mainly exists in the free form,storage space and migration channel for joint and schistosity.Numerical simulation software Fluent is used to simulate the steady state of gas in tunnel space,and the change of gas mass fraction in gas component is obtained.The working surface near the inlet side of the gas concentration is low,the air side of the gas concentration is relatively high,the gas generated from the distribution of the mass fraction of image can be seen,the largest in the gas generation point mass fraction,with wind velocity gas flow gradually to the outlet flow of the tunnel,the stable distribution,the gas pressure distribution showed obvious eddy current state the.This paper presents initial criterion of tunnel gas phyllite Slate:carbonaceous phyllite,high stress,buried depth of 800 meters above the overturned anticline inverted wing.According to these conditions,it is predicted that there will be a possibility of gas tunnel in the 1000 range and the exit section of the tunnel.It is suggested that the ventilation and smoke well be changed to the entrance of the tunnel.