Analysis on Large-Strain Nonlinear Consolidation of PVD-Improved Soft Soils with Non-Darcian Flow Considering Variable Well Resistance and Vacuum Pressure

Abstract

The deviation of water seepage from Darcy’s law has been verified in soft soils with high compressibility. Consolidation behaviors of prefabricated vertical drains (PVD)-improved soft soils caused by non-Darcian flow have been extensively studied, but most of them are based on small-strain consolidation theory, and it is generally assumed that the discharge capacity of vertical drains keeps constant during the process of consolidation. Considering the large-strain characteristic of the soft soils with high compressibility, the consolidation model of soft soils with non-Darcian flow is established in the Lagrange coordinate system. Meanwhile, considering the poor stages of drainages such as bending and silting caused by the deformation of soil layers, the discharge capacity of vertical drains in the proposed model is regarded as changing with time and depth. The feasibility of the solution is verified by comparing the proposed results with existing solutions, and consolidation behaviors under different conditions are investigated. The results show that the influence of non-Darcian flow cannot be ignored when the ratio of the influential zone radius to the radius of vertical drains reaches 15. The common surcharge loading applied to the PVD-improved soft soils has to consider the influence of consolidation results by non-Darcian flow. The difference of vacuum pressure distribution between Darcy’s flow and non-Darcian flow mainly exists in the middle and late period of consolidation. Finally, the proposed consolidation model is applied to the consolidation calculation of Brisbane Port, and the calculation results by the proposed model coincide with the field measurement.