The Computational Analysis On Vacuum Combined Surcharge Preloading Based On ABAQUS

Vacuum preloading and Vacuum combined Surcharge preloading are effective methods to improve soft foundation.Along with our country's construction upsurge,these two methods were used more widely.There are some developments of improvement principle, construction techniques and design theory,but there are more questions to solve such as the depth of improvement and surcharge preloading,effect of vacuum preloading to the environment,computation methods,and so on.This status limited the more application and development of these two methods.More and more researchers' attention in the world focuses on these questions.This thesis researched the questions above via experiment data and theoretical analysis. The main work of this thesis are:(1)Based on the research of improvement principle of the vacuum combined surcharge preloading,the change of underground water,depth of improvement and constitutive model are studied.(2)According to the principle of equality of consolidation degree,two equivalent method of converting vertical drain to layered soil or to drain wells are proposed,and we can use Plane strain FEM to analyze ground with vertical drain via translating it to layered soil foundation or drain wells foundation.(3)With ABAQUS FEA program,the stability of soft soil foundation treated with vacuum combined surcharge preloading was studied.The results showed that the stability of soft soil foundation was related to the degree of vacuum,the depth of treatment,the shear strength of soil,the loading procedure and etc.Then by FEA program,the destabilization of an engineering project was simulated.Lastly some suggestions for construction were put forward.(4)The environmental effect of vacuum preloading was researched,we mainly focused on the safety measure effects in affected soft ground area.