A new method to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou

Abstract

A new method is developed to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou, China. This is achieved by adding some flocculants (floc) to the dredged fills while maintaining a certain level of vacuum pressure through prefabricated vertical drains (PVDs). The floc agent adopted in this study is a mixture of polyacrylamide (PAM) and calcium hydroxide (Ca(OH)2), which would dehydrate soil particles through changing the bound water into free water. The water states transformation occurs inside the soil particles, which would significantly mitigate the risk of clogging around PVDs and enhance the soil permeability, thereby improving the efficiency of consolidation. A number of laboratory tests are conducted to testify this method. Comparison between conventional vacuum preloading method and the proposed method demonstrates that, the new method achieves better improvement of dredged fill in a shorter period of time.