Large strain consolidation model of vacuum and air-booster combined dewatering

Prefabricated vertical drains (PVDs) are an established ground improvement method. Mimicking drinking straws, PVDs are installed to convey vacuum pressure in the ground and lift groundwater. However, the dewatering performance is suboptimal in consolidating fine-grained layers. Practical applications have shown that better dewatering performance is achieved through aiding the vacuum dewatering with an air-booster. Air-boosters are installed in an alternating pattern adjoining PVDs, increasing pore pressures and unclogging pores. This study presented a numerical model for this vacuum and air-booster combined dewatering solution. Taking account of the large strain deformation, this model used the Lagrangian-convective coordinate to track the global and local deformation of the soil layer separately, thus enabling accurate determination of consolidation. This model also considered air-booster induced unsaturated conditions and the associated effects on water flow. The numerical model was verified against field test results and laboratory measurements.