Site-based researches on mechanical behavior of new large-diameter pipes during pipe jacking

The strain responses of each part of the jacking prestressed concrete cylinder pipe (JPCCP) as well as the pipe-soil pressure under three-dimensional construction loads and water-soil pressure are measured in site. It is shown that the axial compressive stiffness of the JPCCP is large enough to sustain jacking forces. Due to the effects of prestressing, it can bear large tensile stress in the hoop. However, the axial tensile stiffness of the JPCCP is insufficient. Through the force analysis of different pipes in axial direction, the friction force between pipe and soil is figured out, which shows that the shorter the jacking intermittent, the less the average friction force. Otherwise,the pipe-soil pressure is sensitive to pipe motion, and the instantaneous maximum value is 500 kPa. After construction, the distribution of contact stress along the tube is not symmetrical or uniform but coincides with the measured strain of the pipe joint ring.