Impact of surface loading on deep excavation response: centrifuge and numerical analyses

In this study, the influence of surface loading on wall and ground behaviour for deep excavations was investigated. Centrifuge tests and finite-element analyses were performed to characterise the effects of various surface loading components, including loading location (es), size of loading area (ABL), given by width (Bs) and length (Ls), and magnitude of load (Q). Results showed that smaller es, larger ABL, and higher Q resulted in larger wall deflection (δw), ground settlement (sv), and lateral earth pressure on the wall (σ′h). The increases in δw, sv, and σ′h diminished close to the greenfield case at es/Hex, Bs/Hex, and Ls/Hex of 1.2, 2.0, and 2.0, respectively, indicating the limit influence ranges of the components. The increases in δw, sv, and σ′h with increasing Bs/Hex were larger than with increasing Ls/Hex, indicating the directional effect of loading area. The effects of surface loading components were evaluated and quantified using a factor (η), based on the stiffness influence factor (IF) with a modification procedure to consider the effects of es, ABL, and Q. Case examples showed that the proposed method was valid and effective in predicting wall deflection and settlement for deep excavations with loads in nearby areas.