Evaluation of ground movements due to pipe-jacking process of large rectangular structures in soft clays

Abstract

Pipe jacking method has been increasingly employed in congested urban areas to construct large-scale underground structures (e.g., subway stations), given its advantages in minimizing interventions on adjacent infrastructures. Nevertheless, it remains challenging to assess the associated ground movements. In this work, we form a numerical model for evaluating the ground movements caused by large rectangular structures in soft clays. The salient features of the model rest on explicitly accounting for (1) continuous frictional sliding at pipe–soil interface and (2) small-strain stiffness of soils. The former is achieved by combining displacement-controlled approach (DCA) and finite sliding contact method, while the latter is included by using inter-granular strain (IGS) based constitutive model proposed by the authors. The built numerical model is applied to a case study of the construction of a subway station in Shanghai, where the model performance is assessed against actual field measurements. We utilize the numerical model to analyze the characteristics of ground movements and the roles played by pipe–soil interface friction and small-strain behavior of soils. Our analyses suggest that, compared with conventional construction methods, pipe–soil interface friction and convergence deformation of structure can be important factors for controlling ground movements associated with pipe-jacking.