The Monitoring And Analysis Of Soil Foundation Consolidated By Surcharge Preloading Combined With Vacuum Preloading

With the development of economy, there are more and more engineering constructions on soft clay ground, thus the techniques for ground treatment are becoming manifold day by day. During the process of engineering practice, a number of new practical techniques has been used, among which, the method of Vacuum Combined with Surcharge Preloading is quite common and new, it has been extensively used in recent years, and obtained both considerable engineering and economic results. However, this method has been still rarely applied and studied on the soft clay of the rockery, and the designing theory is still far from perfect, therefore, it is necessary to have a study on it combined with engineering practice.This paper studies on a project of the rockery, the vacuum degree、 pore water pressure layered settlement、 horizontal displacement of deep soil is monitored by field experiment under the vacuum combined surcharge preloading, it is studied by experiment data and theoretical analysis that the characteristics and effects of large area soft ground improvement through vacuum-surcharge preloading method. it simulates the project with a two-dimensional model based on FEM software ADINA, simulates the deformation of the soft foundation in the Vacuum Combined with Surcharge Preloading, not only the vacuum pressure is applied in the sand layer, but the vacuum pressure is applied in the PVDs elements by the field measurements, Mohr-Coulomb’s model is incorporated into the Biot’s consolidation theory program. a general-purpose program is compiled to analyze the real engineer by use of the plain strain FEM. Comparison with the field measurements indicates that the proposed method indicates that the two-dimensional model can reflect the developing trend of foundation deformation and pore water pressure. Deformation law of the foundation impacted by these influencing factors, such as the spacing of PVD、vacuum degree、 the permeability coefficient of sand drain, is studied by using two-dimensional finite element simulation. The results show that:the spacing of PVD can influence the deformation of row piles most significantly. Reducing the spacing of PVD can significantly speed up the settlement displacement, reduce the lateral settlement and the destabilization of an engineering Project; Increasing the permeability coefficient of sand drain can significantly speed up the settlement displacement and the stability of soft foundation; Increasing the degree of vacuum can improve the depth of treatment and the reinforcement effect.