Experience of Pipe Jacking Tunneling in Gravel Formation

Gravel formation is the most common formation in the Taichung area in Taiwan, where most of the gravels are hard and have high strength and strong interlock between gravels. Methods used for underground constructions in gravel formation are still under exploration due to lack of experience. Thus, the objective of this study is to focus on investigation of Taichung base waste water outflow pipeline construction using pipe jacking method. The analyzed data during tunnel construction include attrition and repair of the machine, torque applied at the cutter face, thrust forces used to push the pipes, encountered problems, and tunnel advancing rate are synthesized and analyzed. For drive distance less than 90 m, the thrust forces used to push the pipes are around 400 to 500 tons. The frictional resistance between the pipe, the outside diameter is 2.85m, and ground is around 0.6 to 1.0 ton/m2. The average advancing rate, time used to push each pipe and torque applied at the cutter head are 20.6 mm/min, 2.9 hours and 260 t-m, respectively.