Study On Experiment Of Vacuum-combined Surcharge Preloading And Analysis About Influence To Pile

Currently vacuum preloading law is widely used in the highway soft- foundation improvement engineering projects,which is one of more effective soft- foundation improvement methods.This soft- foundation improvement method not only may carry on the construction quality stability control well and reduce the time limit for a project, but also bring the ideal economicefficiency and the socialefficiency. Although the construction technology consummates day after day, there are still many problems on the research of improvement mechanism and the fundamental research far falls behind the project practice.Depending on the vacuum preloading experiment of Hang-pu highway Jia-xing section 16-sign , this article does further research of improvement mechanism, and analyses the change of groundwater level ,as well as influence to the pile about the vacuum negativepressure function mostly.Firstly,according to the vacuum preloading experiment, introduces monitoring method and working procedure.Based on the monitoring production,summarizes the change laws of groundwater level, surface settlement, delamination settlement, pore-water pressure, pile displacement, and does further research of improvement mechanism.Secondly, the horizontal displacement occurres to the pile because of the vacuum negativepressure function. Utilizing the simplification computational method of m-law, analyses the change of internal force distribution and horizontal displacement about pile. Utilizing F.E.M software-PLAXIS, carries on F.E.M modelling computation about the pile displacement under the vacuum negativepressure function. Based on the monitoring production, analyses and compares othernesses between simplification computational method and PLAXIS.Thirdly, this article establishes mathematical calculation model and expression of seepage based on Barron-presupposition,and divides vacuum preloading course into unstable seepage and stable seepage. Utilizing unstable seepage mathematical calculation model, calculates the falls of groundwater level,and moreover does further research about change laws of groundwater level.