Research On The Deformation Of The Structures Induced By Vacuum Preloading In Soft Soil Area

The deformation of the structure induced by vacuum preloading in soft soil area is studied in this paper.Soft clay is distributed in the vast area of China with poor engineering properties. And the method of consolidation by drainage is usually used to treat the soft clay ground. In recent years, vacuum preloading is extensively used to treat the soft clay ground as one kind of the method of consolidation by drainage, and it has got lots of project benefit and yield good economic returns. Although there have been many studies on mechanism of vacuum preloading and the method to calculate its settlement, it is lack of system study on the deformation of the foundation induced by vacuum preloading and the influence factors. As a result, it will be helpful to go deep into the two fields for the further application of this method.In this paper, the mechanism of vacuum preloading and the vertical and lateral deformation (mainly discuss the lateral deformation) of the structures induced by vacuum preloading is analyzed. Meanwhile, the influence factors of deformation and the lateral range of influence is also discussed in this paper.First, three-demensional consolidation of the element is simplified to two-demensional consolidation. And finite element method (FEM) is used to analyze it with four-node isoparametric element. Then FEM program is compiled and improved to calculate the soil's consolidation and deformation under negative pressure by using FORTRAN. And in comparing with the measured value, this program is proved to be reasonable and feasible to calculate the deformation.Last, the pertinency factors of deformation by vacuum preloading are analyzed individually by using the program, including the plugging depth and saparation of the draining board, coefficient of permeability, hypolemmal vacuum degree and consolidation coefficient of soil. And the result indicates that the deformation by vacuum preloading relates to the plugged depth and saparation of the draining board, coefficient of permeability, hypolemmal vacuum degree and consolidation coefficient of soil. The lateral range of influence by vacuum preloading relates to the width of reinforcement.