On July 17, the 2019 Zhejiang Science and Technology Award Ceremony was held in Hangzhou City. The project of “Key Technologies for Dredging Mud Compound Vacuum Preloading Foundation Treatment” undertaken by the team from the College of Civil Engineering and Architecture won the first prize of Zhejiang Science and Technology Progress Award.

The eastern coastal areas of China are economically developed but with limited land resources. To solve this problem, large-scale reclamation of tidal flats have been carried out in recent years based on offshore dredged silt. The dredged sludge has a high-water content (100%-300%) and thus lacks strength. Vacuum preloading technology is widely used in the project for foundation treatment. However, long-term engineering practice has shown that for the high-water content dredging silt of the tidal flat reclamation, the traditional vacuum preloading foundation treatment is not very effective, and it cannot meet the requirements of the engineering construction for the strength and deformation of the foundation. A series of accidents such as excessive settlement and pipeline fractures have caused huge economic losses, affecting the normal operation of buildings and even threatening life and safety. 

After more than 10 years of work such as systematic theoretical analysis, indoor testing, field testing and engineering practice, our team established a consolidation theory considering the non-linear change characteristics of dredged silt infiltration, developed a number of new technologies such as staged loading, closing, pressurizing, etc., formed a compound vacuum pre-compression consolidation technology system, which effectively improves the bearing capacity of the foundation, controls the settlement after construction, meets the needs of later engineering construction, and greatly saves maintenance costs.

Application of technology:

Zhejiang Oufei Sluice Project. There are 6 sluices in the first-stage construction, with requirements for high horizontal bearing capacity of the pile foundation, and the treatment of soft foundation. Each sluice has a treatment area of 80,000 square meters and depth of 20 meters. Using the current technology, the horizontal bearing capacity of the pile foundation is doubled.

Zhejiang Industry & Trade Vocational College. The current technology is applied to the construction of a total area of more than 800 mu, and the first phase construction has been put into use.