This paper investigates a basement excavation adjacent to running metro tunnels and underground pipelines in Shanghai soft soil. The zoned excavation technique was adopted to control the deformations caused by excavation. The excavation site was divided into three parts and successively constructed in the order of Zones A, B, and C with the bottom-up method. The field data of retaining walls, struts, columns, surrounding ground, pipelines, and metro tunnels were monitored and analyzed in terms of lateral and vertical deformations throughout the whole construction process. The data indicates that the wall deflection and column heave in Zones B and C were smaller than those in Zone A. The ground surface settlements near the metro lines were effectively reduced by the zoned excavation technique. The deformations of the metro tunnels and pipelines were well controlled within the acceptable limits. A general relation between wall deflection and the excavation area was also proposed based on this and 15 similar cases.

This paper proposes an analytical approach to evaluate the time-dependent bearing capacity of a driven pile in clayey soils by taking the pile installation and subsequent reconsolidation effects into consideration. The process of pile installation is modeled by undrained expansion of a spherical cavity at the pile tip and a cylindrical cavity around the pile shaft. The cavity expansion solution, which is based on a K0-consolidated anisotropic modified Cam-clay model (K0-AMCC), is used to capture the pile installation effects. After pile installation, the dissipation of the excess pore water and the increase of the effective stress in the surrounding soil are evaluated by the radial consolidation theory. Based on the effective stress, the strength of the remolded soil is quantified by the modified Cam-clay (MCC) model and the spatially mobilized plane (SMP) criterion. With the three-dimensional strength of the surrounding soil, the time-dependent bearing capacity of the driven pile is evaluated by ...

This paper presents a generic analytical solution for stresses and displacements developed around an arbitrarily shaped underground opening excavated in an elastic soil/rock mass with biaxial in situ stresses. A series of separable functions satisfying the governing biharmonic equation is employed as the basic stress function for the problem considered. With the basic stress function and the stress rotation equation, the normal stress and the shear stress on the opening boundary surface are expressed in terms of separable function series with unknown coefficients to make use of the boundary condition. Based on the variational theory, the unknown coefficients are determined by minimizing the difference between the real stress boundary condition and the assumed stress function on the opening surface. The excavation responses around different shapes of openings, including elliptical-shaped, ovaloid-shaped, horseshoe-shaped, and D-shaped openings, are investigated and compared with those from the finite-element simulations. The results show that both the stress field and the displacement field agree well with those from the corresponding numerical model, which verify the proposed solving technique. The proposed solution provides an easy, generic, and feasible approach to assess the stresses and displacements developed around an arbitrarily shaped opening, which is simpler and more straightforward than the complex theory–based solutions.