Abstract
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.
Highlights
Massive construction of facilities and infrastructures has been initiated to meet the need for the rapid urbanisation in China
Fast construction, good sustainability and low cost are the goals of foundation pit construction
While traditional support systems such as row pile support, shotcrete support, reinforced concrete caisson support, pile anchor support and diaphragm walls have been widely used in the stabilisation of foundation pits (Chambers et al, 2016; Lam 2018; Qiu et al, 2016; Sun et al, 2015; Wang et al, 2018a; Wu et al, 2018), the main issues are the difficulties in subsequent repair and demolition work, given that for the working shaft, those retaining systems are typically used as temporary structures
Summary
The stresses and horizontal displacement of the retaining piles and steel panels at different excavation stages are numerically simulated based on a 3D FE model built in the Abaqus software platform. (e) As shown in (e)–(g) in Figure 1, steel panels are successively installed on the side-walls of the foundation pit within the depth of excavation. Points from PA 1 to PA 30 and from PB 1 to PB 30 on the tension side of the piles are used in the FE model to monitor the von Mises stress (sM) and horizontal displacement (dh) of the retaining pile at different depths and at different excavation stages. Lateral displacement of the piles in the upper portion is restrained by installation of new supporting members, while for the lower part, it deforms more due to the lack of waist beams (Goh et al, 2017). The piles deformed as a convex shape, which is consistent with the analysis outcomes by Clough
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