Discussion on Construction Method about Shallow Soil Tunnel With Big Cross Section in Severely Cold Region

Tianhengshan tunnel of Haerbin around-the-city express highway is a shallow earth tunnel with a great span in the severely cold area,which passes through the Quaternary system accumulation stratum that is composed of loam.The earth tunnel's design and construction are not very mature at present,and the data and experiences for reference about its construction are very limited,so it is often treated as the weak rock mass in its design and construction,like this,the earth tunnel's characteristic are neglected seriously,and the stress condition of supports is futher intensified.Taking Tianhengshan tunnel as a project background,the excavation method by three stairs and seven steps for the shallow earth tunnel with big cross section is introduced in detail,and the earth tunnel's construction crafts and the main control points for construction procedures are discussed.The Tianhengshan tunnel's construction practice provides references for the similar projects and enriches the earth tunnel's construction method.