Case Study on the Interaction Between Rectangular Pipe Jacking Control and Ground Settlement in Silty Clay

A soil pressure balance rectangular pipe jacking project is investigated to find out the interaction of jacking control and ground settlement in Zhengzhou, China. The dimension of the rectangular pipe jacking excavation face is 6.94 m (width) x 4.24 m (height). The tunnel is 35.6 m long and 10.6 m beneath the ground in silty clay strata. The trajectory of the pipe jacking tunneling machine was measured during the whole construction. Meanwhile the construction sets like cutter pressure, jacking force, and grouting pressure were measured with sensors on the pipe jacking machine. The ground settlement was obtained throughout the rectangular pipe jacking process. The results showed that ground settlement variation started from 7.46 m in front of the cutter and ended with 9.79 m away from cutter. The ground settlement can be divided into four phases according to the settlement increasing pattern which is consistent with the distance from the cutter. The ratio of these four phases settlement is approximately 3:3:2:2. The trajectory of the jacking pipe tail has a nonnegligible effect on the settlement distribution characteristics of the ground. The vertical trajectory variation induces lager settlement increasing than horizontal trajectory. Ground settlement increases during the whole progress, but the increasing amplitude decreases with the increasing of cutter pressure, jacking force and grouting.