Abstract
This paper reports the long-term discharge capacities of 5 types prefabricated vertical drains (PVDs) under clay confinement. The results indicate that under clay confinement, the discharge capacities significantly reduced with elapsed time. The possible reasons for the reduction are creep deformation of the filter of PVD, and clogging of drainage channels. Creep test results indicate that for the conditions considered, the creep deformation is limited, which implies that clogging is a main influencing factor. Test data showed that factors in favor of reducing clogging effect all resulted in an increase on long-term discharge capacity. Based on the test results, an empirical equation is proposed for estimating the long-term in-clay discharge capacity. It is recommended that in term of long-term discharge capacity, a PVD with a larger drainage area per channel and larger shape-factor of drainage channel may be selected. The shape factor is defined as the drainage area per channel divided by its periphery length.
