Study In Consolidation And Seepage Of Vacuum Combined Surcharge Preloading

In recent years, highway is developing rapidly in our country. The value of settlement after completion of works is high in the point view of built highway on the soft soil region, which produced a big problem called bumping at bridge-head. Vacuum combined with surcharge preloading is a good method to reinforce soft foundation. The method has been used to improve soft foundation of highway extensively. But the mechanism of vacuum preloading is not clear, it is necessary to study the method.Based on former research and the position experiment ,firstly the mechanism of vacuum combined surcharge preloading were analyzed and then some facts which affect the reinforce effect of the vacuum preloading are analyzed.Then research the seepage problem in the process of the vacuum combined with surcharge preloading, and built the seepage model of the vacuum combined with surcharge preloading based on Barron-presupposition, so the quantity of percolation of the vertical drain pile can be calculated, then according to unstable seepage mathematical calculation model, calculates the falls of groundwater level, and moreover does further research about change laws of groundwater level.At the last, on the basis of layered method, a method to calculate the consolidation settlement of vacuum preloading was deduced. The elements affecting total settlement during vacuum preloading consolidation were discussed. The principle that defined the coefficient of total settlement correction by the magnitude of combined loading was suggested.