Abstract: With the rapid development of China’s infrastructure construction, the requirements for the soil improvement of the complex sites are getting higher and higher. The traditional vacuum preloading method combined with the conventional surcharge preloading method have the advantages of construction schedule saving without compromise the construction quality. The combined method has been successfully applied in the highway, railway and harbor projects and it is rarely applied in the power plant construction. This paper presents a case history of the application of combination of vacuum preloading and conventional surcharge preloading methods in the soil improvement in the coastal power plant construction in southeast China. The paper also introduces the predesign testing, soil improvement design, key construction sequence and soil improvement quality assurance. Based on the Darcy’s law, the efficiency of the combination method could be explained by the seepage field induced by the vacuum dewatering.

Key words: Vacuum Preloading Combined with Surcharge Preloading, Soil Improvement Design, Soil Improvement Construction, Soil Improvement Construction Monitoring, Preloading Mechanism, Environmental Impact