The effect of incremental confining pressure on the hydraulic properties of PVD

Abstract

Prefabricated Vertical Drains (PVD) has become a standard method in soft soil improvements project to accelerate the soil consolidation time. Due to PVD's primary function as drainage, it should have adequate hydraulic properties, i.e., discharge capacity and transmissivity. This paper evaluates the effect of incremental confining pressure on three types of PVD using an apparatus adopting ASTM D4716, a mechanism to determine the in-plane flow rate and transmissivity of geosynthetics. The apparatus is originally designed to observe the discharge capacity of the PVD. Three types of PVD with different thickness and box channel core shapes were tested under incremental confining pressure in the range of 50 to 200 kPa and varied hydraulic gradients. The results indicated that the reduction of discharge capacity under incremental confining pressure is higher for lower hydraulic gradients, and the reduction of discharge capacity is significant at high confining pressure. The thickness of PVD held an essential role in transmissivity since PVD with greater thickness provides higher discharge capacity and transmissivity.