ANALYTICAL SOLUTION OF BIOT CONSOLIDATION FOR A HOMOGENEOUS SATURATED SOIL UNDERGOING STAGED EXCAVATION

The rebound at the bottom of a foundation pit inevitably occurs due to the excavation’s unloading effect. This effect induces reverse consolidation deformation in the bottom soil. Based on the Biot’s consolidation theory, the reverse consolidation model of a homogeneous saturated foundation subjected to staged excavation is established. The Laplace-Fourier transform method is employed to solve the model, yielding analytical solutions for displacement and excess pore-water pressure of foundation soils. The solutions are validated by comparing them with numerical simulation results and field monitoring data. Parameter analysis shows that a larger horizontal permeability coefficient accelerates consolidation and increases rebound after excavation. An increased foundation rebound modulus reduces rebound and speeds up consolidation, effectively enhancing foundation pit stability. The Poisson's ratio of the foundation has minimal influence on soil rebound during excavation. The total rebound at the end of excavation increases with the construction period’s duration. In multi-stage excavation with the same total construction period, a higher excavation rate in the last stage results in a smaller rebound and a larger accumulated negative excess pore-water pressure.