Calculation of Pit Excavation Rebound Deformation Considering Two-Dimensional Reverse-Consolidation Effect

For soil rebound deformation induced by pit excavation, most previous studies adopt the total stress method for analysis. However, this approach neglects the reverse-consolidation behavior of soil and therefore fails to capture the transient response of soil rebound deformation at the pit bottom. In this study, a two-dimensional reverse-consolidation model of the surrounding soil subjected to staged pit excavation is established. The boundary transformation method and the integral transform method are used to derive a semianalytical solution for the excess pore-water pressure. Based on this solution, analytical expressions for the rebound deformation at the pit bottom and the sectional average degree of consolidation are further developed. The validity of the proposed method is verified by comparing it with finite-element numerical results. Parametric analyses indicate that an increase in the horizontal permeability coefficient of the soil accelerates the reverse-consolidation process at the pit bottom and results in a larger rebound deformation at the end of excavation. A wider excavation pit results in a greater rebound deformation but a slower reverse-consolidation rate, yielding a smaller degree of consolidation upon completion of excavation. When the horizontal permeability coefficient is relatively small, the influence of the retaining wall length on reverse-consolidation at the pit bottom can be neglected. Moreover, the rebound deformation increases with excavation duration, whereas the duration and distribution of excavation interruptions have negligible effects on the final rebound deformation at the pit bottom.