Abstract: This paper presents an innovative vacuum combined surcharge preloading technology system for the soft soil improvement. This system seamlessly incorporates connection, water-gas separation, clogging-resistant prefabricated vertical drains, and surcharge-assisted dewatering to minimize the vacuum loss, to avoid the pipe clogging issues, and to accelerate the soil consolidation. Using a municipal road project in Zhuhai’s West District as a case history, this paper explains the technology’s principles, implementation, and outcomes. Field data shows an average soil consolidation of 94.2% after 124 days of preloading, with only 1-2 cm settlement over five years and an estimated post-construction settlement of about 13.5 cm. Physical and mechanical property tests indicate that improved soil demonstrated an 8.6% increase in the natural density, 85.7% growth in the cohesion, and 155.6% improvement in the internal friction angle. Specifically, the natural density, the cohesion, and the internal friction angle increased by 8.6%, 85.7%, and 155.6% respectively, while the natural water content, the void ratio, the plasticity index, and the liquidity index decreased by 31.3%, 30.4%, 9.7%, and 31.6% respectively. These results indicate substantial enhancements in overall performance, with treatment outcomes exceeding expectations.

Key words: Vacuum Combined Surcharge Preloading, Surcharge-Assisted Dewatering Technology, Water-Gas Separation Technology, Clogging-Resistant Prefabricated Vertical Drains, Soft Soil Improvement