The Settlement Calculation And Analysis Of Soft Soil Treatment By Vacuum Preloading

Settlement Calculation of foundation is the main matter in soft soil treatment by vacuum preloading. Multiple methods have been applied succefully in the settlement calculation, while these methods have their own specialty and appropriate method should be chosen on the basis of the practical conditions of the project.This paper focuses in the practical demand of the soft soil treatment projects at Binhai New Area in Tianjin. Summarizing the predecessors’achievements, one practical inverse analysis method based on Terzaghi’s one-dimensional consolidation theory has been raised in this paper. After studying numerical simulation of vacuum preloading, another inverse analysis method using the measured data of lamination settlement is raised and written into application program. The main work and conclusion is listed as follows:(1)The mechanism of soft soil treatment by vacuum preloading is summarized and new processes and improved methods are introduced; Common settlement calculation methods are also generalized, and their advantage and disadvantage and application scope are presented.(2)Against the features such as multilevel loading, uneven distribution of preloading and difficulty in controlling post construction settlement in practical project, one practical inverse analysis method based on Terzaghi’s one-dimensional consolidation theory has been raised to calculate the consolidation parameters. These consolidation parameters results can be used to predict the post construction settlement, providing reference for unloading.(3)In order to invest further the mechanism of the vacuum preloading and study the law of soil deformation in vacuum preloading. The three dimensional finite difference software, FLAC3D, is adopted to simulate one vacuum preloading treatment. The results show that numerical model can properly indicate the law of transmission of vacuum, the growth of effective stress and deformation in soil.(4) For the purpose of assessing reinforcement effectiveness of different soil layer in vacuum preloading, one program is written using the measured data of lamination settlement based on Fortran language to inverse analyze the consolidation parameters of soil, and the simulation result curve is compared with the measured curve to verify the feasibility of the inverse analysis method.