Highway Tunnel Crossing Fractured Fault Zone by Drilling and Blasting Method in Mountain-Plateau Region
This paper presents a case history of the highway tunnel construction of Xinjiang Wuwei Highway Package PPP Pro-ject YRTJ-04 Bid Section Bashkorgan Tunnel 2.Based on the environmental and geological conditions at the tunnel site,several technologies,such as,the tunnel excavation advanced prediction technique,tunnel construction ventilation methods,the oxy-gen supply method during the tunnel excavation as well as the drilling and blasting methods for the crossing over the fractured fault zone,are comprehensively studied.The results show that,in view of the tunnel construction in Xinjiang's cold and high-altitude areas,considering the environmental factors brought by the increase in altitude,the design of the tunnel ventilation system is optimized accordingly.The technical parameters of the tunnel construction ventilation are defined to meet the require-ments of the on-site construction ventilation;According to the characteristics of Xinjiang's high-altitude,low pressure and an-oxic environment,the recommended value of the critical oxygen supply altitude is determined,and the corresponding labor in-tensity classification is carried out according to the tunnel construction procedures.The oxygen supply standard required to con-sider the factors of labor intensity in different procedures is determined,and the oxygen supply scheme for the construction of Bashkorgan Tunnel 2 is proposed;In view of the tunnel crossing fractured fault zone and the well-developed joint fissure area,the key technologies such as the comprehensive advanced geological prediction detection and the concentrated water pressure smooth blasting are adopted to ensure the safe construction and the construction efficiency of the tunnel.