WORKING OF PREFABRICATED VERTICAL DRAIN- ÃÂ CASE STUDY
|Aniket S. Shukla 1, A. R. Kambekar 2
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Prefabricated vertical drains (PVD) are commonly used to decrease the drainage path within soft soils to accelerate the time of primary consolidation. Prefabricated vertical drains are displacement drains of small volume that exhibits considerably with fewer disturbances to the soil mass than the displacement sand drains. Disturbance to soil mass due to installation of PVD at three construction sites in Navi Mumbai area is evaluated in this work. This work emphasizes ground improvement mechanism for proposed embankment for double track broad gauge railway line between Belapur-Seawood-Uran areas in Navi Mumbai for chainage 19000 to 20500 along the proposed railway track. The study of the soil in this geographical region indicates that the top of the stratification contains the yellowish stiff clay. The next layer observed in the stratification contains the soft grayish marine clay which is then followed by yellowish stiff/hard clay with gravels. The subsequent layers of stratification are completely weathered rock which was then observed by moderately weathered rock. The data collected and analyzed in this study includes general soil details, index properties of compressible soil, shear strength properties, consolidation properties and preconsolidation pressure. It has been observed that the time required for consolidation with prefabricated vertical drains is expected to be shorter as compared to the time required for the preloading alone without PVD. The closer the spacing in between prefabricated vertical drain the shorter the time required for the consolidation process. The expected consolidation settlement achieved by PVD is slightly higher than actual field consolidation settlement.