Abstract
The vacuum consolidation method with prefabricated vertical drains (PVD) is one of the most effective methods to improve the soft ground. In this method, the PVD installed in soft ground was bended along with the consolidation settlement. As a result, the drainage performance of the PVD might be decreased. A series of laboratory tests were performed to evaluate the bending effect on the consolidation behavior in PVD. First, the large scale model tests were performed to measure the bending shape of PVD by the vacuum consolidation. In these tests, the clay slurry at a water content of 150 % was consolidated under the vacuum pressure of 60 kPa in the consolidation cells, which were 5 m in height and 30 cm or 76 cm in diameter. Second, the permeability tests for PVD were carried out under a given constant water head difference. In these tests, three types of PVD were used as samples, i.e., the straight PVD, the moderately-bended PVD whose shape was observed in the large scale consolidation test and the sharply-bended PVD. It was confirmed, based on all the test results, that the consolidation speed was not delayed even by the bended PVD on usual site.
