Non-uniform Consolidation of Soil and Influence of Corresponding Clogging Effect During Vacuum Preloading

Non-uniform consolidation of dredged soil under the vacuum preloading and corresponding clogging effect were investigated by series tests. Water content and permeability of soil at different consolidation distances and time were measured during the vacuum preloading. The drainage water volume and drainage rate in the test were also recorded. Test results showed that the uniform soil became non-uniform once the vacuum preloading started. Permeability of soil near the drainage boundary decreased by 50-100 times at the very beginning of vacuum preloading, leading to a serious clogging effect that reduced the drainage rate of soil by around 90% at the same time. Non-uniformity and clogging effect of soil reached the peak value after 24-48 h vacuum preloading in different cases. Based on the test results and Ruth theory, it was found that lower water content, higher salt content, lower vacuum pressure and flocculant additive relieved the clogging effect and made the soil more uniform after the consolidation. Finally, comparison between test and analytical results clarified that the non-uniformity and clogging effect should be considered in the consolidation of soil under the vacuum preloading.