Key Technology Of Expressway Bao-ding No.2 Tunnel Construction From Pan-Zhi-Hua To Da-Li

With the development of our country's traffic network to the west,the number of highway tunnels and the proportion of the total mileage of the route are getting higher and higher,and the situation of crossing the coal seam gas stratum and the broken water gushing zone of faults is becoming more and more common,which not only brings great potential safety hazards to the tunnel construction,but also makes it difficult to maintain and manage during the operation period.Based on Baoding No.2 Tunnel of Panzhihua-Dali(Sichuan border)Expressway,this paper mainly adopts the research methods of data investigation,theoretical calculation and field practice demonstration,aiming at the construction technology and ventilation technology of Baoding No.2 Tunnel crossing coal measures stratum,based on the difficult problems of coal seam and gas outburst and large water inflow in fault fractured zone during tunnel construction.And advanced curtain grouting water shutoff technology has been studied in depth.(1)According to the general design scheme,construction preparation,danger prediction,outburst prevention technology and safety protection measures that need to be solved urgently in the construction process of crossing coal measures strata(coal seam or semi-coal and semi-rock),the construction methods and methods of tunnel stone-door coal uncovering are put forward and formulated.Specific measures for prevention and control after gas emission.(2)By summarizing the ventilation modes and selection principles of long tunnel construction,relying on the actual engineering situation of Baoding No.2 tunnel of Panda Expressway,and based on the calculation of construction ventilation and the selection of construction ventilation equipment,the dynamic management scheme of ventilation management in construction site is put forward.(3)By summarizing the preparation work of advanced curtain grouting technology after a large amount of water gushing during tunnel construction,a strict and feasible grouting construction scheme is formulated,and the safety and effect acceptance of the grouting results are carried out.The research results have been well implemented in the construction of Baoding No.2 Tunnel of Panda Expressway(Sichuan border).The thorny problems faced in the construction process have been solved in time,and the safety,quality and progress of the construction have been effectively guaranteed.It has created certain economic and social value for the construction of the project and has certain reference significance for similar tunnel construction.