A new model to predict ground surface settlement induced by jacked pipes with flanges

Abstract

Ground surface settlement is one of the critical parameters that needs to be controlled strictly during pipe jacking. The calculation model for estimating the ground deformation induced by pipe jacking is scarce in the literature, especially for pipes with irregular cross-section (e.g., circular pipes with flanges). In this study, considering the pipe-soil interaction, the distribution characteristics of frictions between pipe and soil, and the support force at the tunnel face, a settlement formula is proposed for a single jacked pipe using the Mindlin’s solution and the Stochastic medium theory. Based on the cavity expansion theory, a relationship for calculating the circumferential plastic zone is developed considering the effect of flanges. The distribution of the plastic zone around the pipe and the superimposition effect due to multiple pipes are discussed. Finally, a correlation is established to estimate the ground surface settlement for three types of multiple jacked pipes with different spacing. A case study of a subway station project using the Steel Tube Slab (STS) method is presented. Comparisons of ground settlement from field measurements and theoretical calculations show that the proposed approach can reasonably predict the ground surface settlement for multiple jacked pipes.