Perbaikan Tanah Lempung Lunak Dengan Metode Prefabricated Vertical Drain (PVD)

Abstract

In Kapal Betung toll road project (Kayu Agung - Palembang - Betung) in South Sumatra, the subsoil consists of soft clay soil. The long-term problem of a slowdown in consolidation is a problem that needs to be addressed in this type of soil. One of soil improvement methods to accelerated consolidation process for increasing the soil strength process is the application of Prefabricated Vertical Drain (PVD). PVD method must be accompanied by a initial load to increase the pore water pressure, so that the consolidation can proceed. Soil is a material commonly used for a initial load, not only soil but also vacuum pressure can also be used as a initial load. Based on the analysis, the value of settlement consolidation in this project was between 0,37 and 1,32 meters with a variety of natural consolidation periods ranging from 16,66 to 35,75 years. When using PVD with a 1 m distance and a reference value of ch/cv 1,5, the time of consolidation is 4 to 10 weeks. It can be concluded that PVD can accelerate the consolidation period. When we use PVD combined with loads in the form of landfill and vacuum pressure, PVD precharge construction time is 14 to 126 days with high of initial load soil precharge levels 7,61 to 9,86 meters, while the construction time for vacuum PVD method is 6 to 14 days with a precharge pile height of 4,67 to 6,92 meters. From the results of the analysis, it can be concluded that the vacuum method has advantages that it doesn’t take a long time to make a slopes contruction as a initial load. Vacuum method also requires less soil as a initial load needed than the preload method. It can be happened because of the vacuum pressure can replace ± 4 meters of landfill.