Failure Mechanism of Soil Nail—Prestressed Anchor Composite Retaining Structure

Enhancing the strength of retaining structure with soil nails and prestressed anchors is a new technique that can be used in the excavation of deep foundation pit. Finite element analysis (FEA) based on ABAQUS is presented in this paper to investigate the failure mechanism of such retaining structure. The model used in the FEA is firstly validated by comparing the modelled results with field measurements for a specific case. The model is then extended to investigate the influence of the prestressed anchor on the (1) horizontal deformation of foundation pit and (2) the distribution of axial forces along the soil nails. It is found that the magnitude of anchor force is the key factor governing the performance of the entire retaining system. However, the influence of the prestressed anchor is sensitive to the rigidity of the concrete surface layer of the retaining structure. Based on the results of the modelling, the failure mechanism of soil nail—prestressed anchor composite retaining structure is discussed.