Abstract: This paper presents a case history of improvement of thick soft soils by using a combination of vacuum preloading and surcharge methods. The subsurface conditions of the Economic Development Zone of Golan, Zhuhai, consist of hydraulic dredged soils and mucky soils with an average thickness of 25 meters. The soil improvement technique and construction monitoring results are analyzed. The results indicate that the allowable bearing capacity of the surface soil is 100 kPa and the capacity of the deeper soils could be 80 kPa. The average ground settlement of the site varied from 153.14 cm to 202.79 cm. The vacuum preloading combined with surcharge has the characteristics of short construction duration; safe installations, and excellent improvement result.

Key words: Vacuum Preloading Combined with Surcharge, Thick Mucky Soils, Construction Monitoring and Testing, Surface Settlement, Ground Displacement, Degree of Consolidation