Consolidation by prefabricated vertical drains considering the time dependent well resistance

The rate of consolidation by prefabricated vertical drains (PVDs) is closely related to the well resistance, which mainly depends on the discharge capacity of PVDs. According to the existing laboratory tests and field investigations, the discharge capacity of PVDs will decrease with the development of consolidation due to its deformation and siltation and so on. Based on this consideration, in this paper, the discharge capacity was assumed decreased exponentially with time, which resulted in an increase of the well resistance with time during consolidation. Then, a closed-form solution considering the time dependent well resistance for a vertical drain system was developed based on the equal strain condition. Comparisons were presented with some existing solutions for the excess pore water pressure and for the radial average degree of consolidation. The influences of the time dependent well resistance on consolidation rate were then analyzed and the application of the present solution was discussed.