Abstract:In response to the problems that the sandy soil in the water-rich sand layer is prone to collapse, resulting in the weakening of bentonite slurry friction reducing effect and the increasing jacking force caused by construction halt during restart, a series of pipe-jacking model tests are conducted to investigate the influence of different mud sand content and different resting time on the effect of mud drag reduction and the changing characteristics of pipe jacking force. The results show that as the sand content of the mud increases, the friction between the pipe jacking and the mud interface increases exponentially. The pure slurry can reduce the friction force by 90%. When the sand content of the slurry is less than 20%, the sand content has little effect on the friction reduction effect, and the friction reduction effect is only reduced by 5%. With the increase of sand content in slurry, the effect of resting time on friction force between jacking pipe and slurry interface increased. When the sand content of the slurry is less than 60 %, the residual jacking force of the pipe-soil interface is not relevant to the resting time. When sand content reaches 80%, the residual friction strength increase of approx. 6% to 8% after 24h resting.