Abstract
The vacuum preloading method is commonly adopted for improving the soft ground that the embankment of the railway line is laid on. The PIV (Particle Image Velocimetry) technique is a powerful tool in observing the formation of the soil column, a phenomenon that is unique to the dredged slurry when treated by vacuum preloading. However, it is not clear to what extent the motions of the slurry particles can be represented by the PIV tracers. In this paper, a mesoscopic model has been established by using the CFD-DEM method to reproduce the vacuum consolidation process of the slurry, in which the PVD (Prefabricated Vertical Drain) membrane, the slurry particles, and the tracers are described by the DEM, and the pore water is governed by the CFD method. Eight computational cases that can cover a broad range of material parameters governing the PIV model tests on the dredged slurry have been designed and studied by the established model. The representativeness of the PIV tracer is evaluated by comparing the statistic displacement of the tracer to that of the slurry particles. It is found that for the commonly used tracer, the carbon powder, can reliably represent the particle motions of the slurry since the difference in displacements of the tracer and the slurry particles is smaller than 6.5% if the diameter ratio between the tracer and the slurry particle is within 1.8.
Highlights
Land scarcity is an emerging problem in developed areas due to the fast-increasing population and economy
Questions may arise over the representativeness of the tracers on the kinematic information of the slurry particles during the vacuum consolidation process, which is monitored by using the PIV technique
Solver SediFoam to reproduce the vacuum consolidation process of the slurry, in which the PVD (Prefabricated Vertical Drain) membrane, the slurry particles, and the tracers are described by the DEM, and the pore water is governed by the CFD method
Summary
Land scarcity is an emerging problem in developed areas due to the fast-increasing population and economy. A CFD-DEM-based model was established by Shi et al [8] for reproducing the soil-column forming process under different vacuum pressures. The CFD-DEM method is superior in explicitly resolving the motions of each slurry particle, which can help to understand the soil column phenomenon from a microscopic-scale view. Questions may arise over the representativeness of the tracers on the kinematic information of the slurry particles during the vacuum consolidation process, which is monitored by using the PIV technique. To this aim, a microscopic model on vacuum consolidation of the slurry has been built using the CFD-DEM method.
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