Application Of Shallow Vacuum Preloading And Dynamic Consolidation With Dewatering In Foundation Improvement

With the development of coastal areas, the land reclamation project has become the main way to solve the problem of strained land. The hydraulic fill mud with high water content, large compressibility, and low bearing capacity is weak in strength. Because of this, the hydraulic fill mud should be treated effectively before being used in engineering construction, otherwise it may cause the earth's surface to produce the large differential settlement, cracking even destroy the superstructure.This paper firstly reviews the research history of foundation treatment. Combining with an engineering case in Tianjin coastal areas, we analyze the shallow vacuum preloading method and dynamic consolidation with dewatering method. We analyze and compare the reinforcement mechanism, construction technology, monitoring test, characteristics and application scope of the two methods. Combined with engineering practice, we study the design, construction, monitoring and inspection of the two methods in practical application, summarizing their respective advantages on soft soil foundation treatment, and explore the limitations and problems during application of the two methods.The results show that:(1) The shallow vacuum preloading method and dynamic consolidation with dewatering method achieve good effect in soft foundation treatment in the engineering practice, and the two methods can both be applied in the soft foundation improvement to increase land area;(2) The shallow vacuum preloading method which develops from the traditional vacuum preloading method, is a innovative method for the hydraulic fill mud in Tianjin coastal areas. It is especially applicable for the treatment of hydraulic fill mud with the moisture content of 100% or more, and the soil can achieve the operation conditions to carrying the deep vacuum preloading method through the primary treatment by shallow vacuum preloading method, or for the treatment of hydraulic fill mud with the moisture content from 60% to 70%, but the reinforcement depth should be in 4 m to 5 m condition;(3) The dynamic consolidation with dewatering method can be used in the treatment of various types of soil, including general clay, silty soil and sandy soil, but this method is not suitable for the muddy soil with high moisture content;(4) Both the shallow vacuum preloading and dynamic consolidation with dewatering method have advantages of low cost and short construction period in foundation improvement, but the scope of application of two methods are different. The application of the two methods should be chose based on the actual engineering situations.