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 (e_s), size of loading area (A_BL), given by width (B_s) and length (L_s), and magnitude of load (Q). Results showed that smaller e_s, larger A_BL, and higher Q resulted in larger wall deflection (δ_w), ground settlement (s_v), and lateral earth pressure on the wall (σ′_h). The increases in δ_w, s_v, and σ′_h diminished close to the greenfield case at e_s/H_ex, B_s/H_ex, and L_s/H_ex of 1.2, 2.0, and 2.0, respectively, indicating the limit influence ranges of the components. The increases in δ_w, s_v, and σ′_h with increasing B_s/H_ex were larger than with increasing L_s/H_ex, 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 (I_F) with a modification procedure to consider the effects of e_s, A_BL, 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.