Pipe Jacking in Sandy Soil Under a River in Shenyang, China

This paper provides an overview of a pipe jacking project of the Wu’ai Electric Power Tunnel, funded by Shenyang Power Company and constructed under the supervision of China Railway Construction Corporation in Shenyang, China. This project involves excavation of three jacking shafts and drilling tunnels by pipe jacking technique. A 3.5 m diameter reinforced concrete pipe was jacked below the Hunhe River over a length of 1000 m. Hand shield approach was adopted on the river bank as an alternative of operating an earth pressure balance micro tunnel boring machine under the river. The stress–strain behavior of shafts under the maximum applied jacking forces was evaluated by means of finite element analyses. Monitoring data (i.e., tunnel alignment, jacking forces, resistance at the jacking head, frictional resistance and torque of the boring machine) were collected during the jacking process and are presented here. A tunnel face collapse was experienced; the corresponding countermeasure actions adopted are described. The jacking design (i.e., pipe, jacking machine, and shafts) and remediation for tunnel failure may provide reference for future projects and assist in the development of new design guidelines.