The Research Of The Mechanism Of Underwater Vacuum Preloading Technique To Improve Aqueous Soft Soil

The research of the mechanism of underwater vacuum preloading techniqueto improve aqueous soft soil was established by China Harbour EngineeringCompany (Group) as a Key Technical Development Project for Year 2002. Thestudy was directed toward the research and development of the mechanism ofunderwater vacuum preloading technique and the technological process forimplementation of underwater vacuum preloading. During the feasibility study,The working mechanism of the water on top of the sealing membrane was studiedthrough laboratory model tests and theoretical analyses. With two years' carefulstudies, the working mechanism of underwater vacuum preloading is now given,and a rational technological process for implementing underwater vacuumpreloading as well as a monitoring method has been preliminarily worked out. Themajor conclusions drawn from the studies are that, (1) the pre-loads produced bythe underwater vacuum preloading equal the sum of the water pressure on thesealing membrane and the vacuum beneath the sealing membrane. In thelaboratory tests, when the water head was 10 m, the whole water pressure (100kPa) could be converted into pre-loads. (2) During the implementation ofunderwater vacuum preloading, the infiltrated flow of water from outside theboundary of soil being consolidated wouldn't result in the failure of the soil mass.(3) the laboratory model tests of underwater vacuum preloading have verified theworking mechanism of underwater vacuum preloading and the conversion ofwater pressure into pre-loads.