Field test of mechanical properties of large diameter concrete jacking pipe in soft soil

Annular reinforcing steel bar stress and pipe-soil contact pressure during pipe-jacking were monitored on the spot. The differences of the active contact pressure from the related research results were analyzed. The results show that when the pipe is pulled in the stable slurry interface which has been already formed, and since the test pipe was pulled into the tunnel bore, the distribution of contact pressure tends to be uniform and remain stable. But the contact pressure will increase suddenly when grouting, and return to normal gradually after stopping pulling. The lateral force of the pipe is also stable, though not big, mainly showing compressive stress, whose changing is controlled by pipeline axial deviation and grouting. Therefore, the pipe is in a state of eccentric compression in the test. Compared with the results of the field test, the specification is rather conservative. Besides, the active distribution of contact pressure is close to the load model developed by Lei Han, which can be used to optimize pipeline structure design. ©, 2014, Shanghai Jiaotong Daxue Xuebao/Journal of Shanghai Jiaotong University. All right reserved.