The Study Of The Compression Modulus Calculation Of Vibroflotation Composite Foundation In Dalin Dragon Spring Extate

The research of the theories and the applications of composite foundation are quite active in civil engineering field at present. Especially in the recent thirty years, the technology of composite foundation have obtained bigger development. The vibroflotation is the main method of the ground treatment. But this method is still in the state of semi-theory and semi-experience. Because some calculation are immature, and some parameters are used depend on the engineering experience.The development and the research present situation of composite foundation are summarized in this article and the extant main questions of composite foundation are pointed. The methods of ground treatment in common use in Dalian are introduced. Some details of case of failure and success of ground treatment are also presented here. Four dwelling buildings with 18 stores were proposed on a ground consisting of soft marine clay, and this ground was treated by vibroflotation. From this engineering the research of bearing characteristics and the method of parameters for vibroflotation composite foundation are carried on systematically. The new methods of design and calculation of vibroflotation composite foundation are put forward.It was generally believed that the soft marine clay treated by vibroflotation composite foundation can only be applied for lower building. If not the stone columns cannot gain enough side support from the surrounding soft clay, and the stone columns will expand to the surrounding. This engineering experience proved that the ground with soft marine clay can also be treated with vibroflotation for higher buildings and composite foundation can achieved good result. In this article the result of ground treatment with different vibrator power is compared and defferent odditional stress on different layer is compared using the datum of plate load tests. By the comparing the curves of load tests and the curves of raft-foundation settlement observation, the author point out the current theory limitation of the composite foundation parameter calculation. Based on the comparison of the load tests and the settlement curves, it was founded that the modulus on initial linear part of the curve of load tests does not truly express the compression of the composite ground for the raft-foundation and that the settlement is related with later linear part of the curve of load tests. In this article the calculation method of the deformation modulus of two layers is presented by analysis the load-test data of the composite ground within the plate influence. And it is close that the calculation settlement using the modulus compared with the calculation settlement from the measured settlement of the buildings. The two layers modulus from load-test is avoid of the defect of the using method which only one layer modulus of deformation is gained.The relationship between a vibrator power performance indicators and stone column body strength is established by the study of the compression modulus theory and the vibrator character, which is called dynamic method. And is proved by finite-element modeling. This makes the designer design more impersonally and the results accord with the settlement observation.