A Comparative Case Study on Drainage Consolidation Improvement of Soft Soil under Vacuum Preloading and Surcharge Preloading

Based on an improvement project of soft soil ground in Zhuhai City on the Pearl River Delta, a comparative study on vacuum preloading and surcharge preloading was performed. The ground and stratified settlements, excess pore water pressure, and the degrees of consolidation of soft soil are analyzed, along with the horizontal displacement and soil strength. The results show that surcharge preloading results in smaller secondary consolidation settlements than vacuum preloading. Primary consolidation settlement quickly increases with increasing excess pore water pressure of less than -40 kPa in vacuum preloading, while also increasing between 20 kPa and 25 kPa in surcharge preloading. The sharp increase in the strata permeability coefficient will induce the increase in strata consolidation degree and has little effect on the ground consolidation degree. The surcharge preloading can be given priority to reduce the settlement foundation in the service stage.