Nonlinear consolidation of multilayer soil under cyclic loadings

Abstract

This paper proposes a uniform approach for modelling one-dimensional nonlinear consolidation of multilayer soil under various cyclic loadings based on the differential quadrature method. Various cyclic loading forms and boundary conditions are readily treated. The current differential quadrature formulation using harmonic function coefficients (HDQM) is proven more efficient in solving the consolidation problem of multilayer soil under cyclic loadings than conventional differential quadrature formulation using Lagrangian interpolation polynomial. The computation indicates that the pore pressure and average consolidation degree of a multilayer soil are highly dependent on the loading form and the length of the loading period in each loading–unloading cycle. The influence of the various boundary conditions on the distribution of the pore pressure in soil layers and consolidation rate is also discussed. An analysis on field measurements in Ningbo subway line 1 is presented to demonstrate the application of the proposed method. Analysis reveals that at the initial stage of the subway services, the main settlement is contributed by the consolidation settlement, which is quite considerable, about 0.5 mm per month. When the Up reach 50%, the consolidation settlement tends to stable state, then, the accumulative settlement becomes noticeable.