Research On The Experiment Of Soft Soil Foundation Reinforcement With Method Of Straight-line Vacuum Preloading

With the development of harbor engineering construction, land for construction at port is becoming scarce gradually. The procedure of creating new construction land with method of reclamation works is becoming more and more popular. This method can not only create new construction land by utilizing shoals, but also solve problems of dredging and refilling in sea-route. Manual backfill soil is almost benthoal silt or dredging mollisol. Natural foundation backfilled by this kind of soft soil is low in bearing capacity, big in deformation and bad in stability. So great deformation and differential settlement would appear when the structure load be loaded. The time duration of sedimentation would be very long as well. The bearing capacity, sedimentation after construction and stability of foundation can hardly satisfy the service requirements. Therefore, the foundation treatment must be carried out. Among the methods of soft soil foundation treatment, vacuum preloading is widely used for its advantages of brief technology, friendly environment, high-efficiency and economical. In the course of practical construction and application, many methods of construction come forth aiming at different field environments and construction conditions. Straight-line vacuum preloading is popular for its cost savings and improved ergonomic design.Based on the pilot projects of soft soil foundation treatment in 3# engineering of Dayaowan port in Dalian which carried out in-situ test with methods of vacuum electro-osmosis and straight-line vacuum preloading, the paper summed up and contrasted different characteristics of electro-osmosis method and vacuum preloading in the treatment of soft soil foundation. Besides, the article researched stabilizing effects of different treating methods. For the straight-line vacuum preloading, according to the characteristic that it is rich in clay content, the paper chose four draining boards of different equivalent diameters filtration membrane to carry out comparative trials in order to explore stabilizing effects of backfilled soft soil drainage solidifying under the action of straight-line vacuum preloading and plastic draining boards with different equivalent diameters filtration membrane. The paper also studied foundation treatment effects of plastic draining board filtration membrane with different equivalent diameters and different materials. At the same time, the paper adopted original“straight-line”joining method of suction pipe which left out conventional procedure of paving sand cushion as filtrate permeable layer and heighten vacuum transmission rate and depth. Vacuum preloading intensity was controlled by vacuum pressure under membrane and intensity of vacuum action to boost stabilizing effect and confirm appropriate types of draining board and rational construction parameter, all of which can be provided as dependable gist for designing and constructing of a large area of soft soil foundation treatment.On the basis of experimental investigations, the article analyzed experimentation of different foundation treating methods and actual processing results. The paper also demonstrated advantage of vacuum preloading that it can ameliorate soil nature and enhance work efficiency evidently. Finally, the paper summarized advanced experience of this method and put forward ameliorating suggestions for problems occurred during construction, which can be provided as gist for spreading and application of straight-line vacuum preloading. The research results can be referenced by similar engineering on designing and construction.