Consolidation Characteristics and PBD Application in Deep Soft Ground

Various ground improvement methods were applied to obtain the preceding settlement of the soft ground and strength increase and the vertical drain method has been used to reduce the required time for consolidation of the soft ground. Especially, the plastic board drain (PBD) has been widely used among the vertical drain method. In this study, the behavior of characteristics was evaluated by operating a compound drainage capacity test, a smear zone test about the plastic board drain (PBD) method applied in soft clay in deep depth. Also, the scanning electron microscopy (SEM) was then taken cutting the filter section of the PBD. From result of the tests, it was found that change of settlement through load steps resulted from dissipation of pore pressure and it was also found that the drainage capacity of vertical drains was considerably reduced with pressure increase and time elapse. In the case of SEM, it showed that clay particles were stacked outside of the PBD but almost no clay particles were stacked inside of the PDB. In the case of the double core PBD, fine-grained soil was not observed with the naked eye when the test was performed.