Numerical analyses of a prefabricated retaining system for foundation pits in silt soils

This paper first introduces a new prefabricated recyclable retaining system that can be used to stabilise foundation pit excavation, particularly in urban areas. The new retaining system mainly consists of a steel frame, steel panels and bead polymer layers. A three-dimensional numerical model is built in Abaqus software to carry out numerical analyses on such a system that is used for a working shaft excavated in silts for a pipe-jacking project in Northern China. The model is first validated by comparing the analyses results against field monitoring data. After the validation, the model is further used to investigate the stresses and deformations of the main structural members of the new retaining system, including the H-piles and steel panels. The ground surface settlement corresponding to the type of the retaining system is also studied. In addition, the influence of the thickness of steel panels and pile embedded ratio on the stresses and deformations of the panels and piles is examined. The retaining system introduced in this study is shown to have good potential to be used in the stabilisation of foundation pits in urban areas from the perspective of safety, fast construction, recyclable utilisation and reasonable cost.