Relationship of jacking force and average friction with jacking path in pipe-jacking construction

Jacking force and average friction both are important parameters in pipe-jacking construction, the former can affect construction scheme greatly; the latter can embody whether the construction crafts are good. In the construction of a long distance and large diameter pipe-jacking tunnel with small curvature in Shanghai, jacking forces along jacking path are measured for two pipes. Based on the on-site observation, relationship of jacking force and average friction with jacking path and its influence factors are analyzed. Due to complexity of the influence factors, jacking force increases with violent vibration along jacking path, average friction also vibrates initially at high level. As a result of construction stabilization such as formation of slurry-cover, stabilization of axis-control, and dilution of influence factor along jacking path, average friction decreases quickly and tends to stabilize after initial stage. If construction measures are sound, average friction for long distance pipe-jacking with small curvature can be controlled at a low level. At last, some suggestions about construction are put forward.