Hefei Unsaturated Expansive Soil Creep Test And Model Research

Our country is one of the widly range of national about expansive soil distribution, the mosdly soil areas is in the south and southwest of Hefei. Expansive soils distributes around Hefei and its surrounding cities will create many problems in project construction, such as the retaining wall will be shifted after the completion、 slope will be instability as time passed、long-term deformation of the high-rise buildings, Cracking of the wall and road surface subsidence, etc., these phenomenans after the study showed that it is associated with the expansive soils creep character. Now there are a lot researches on expansive soil creep at home and abroad, and also get some new progress, however, due to regional locality and particularity, some empirical formula or combination of components model mathematical calculations does not fully reflect the real creep of the soil. So to solve this problems and with the big development of Hefei, it’s necessary to research the creep characteristics of typical expansive soils in this area. On the one hand, it can improve and develop soil mechanics theory, on the other hand it can provide parameters and predictability, to ensure the smooth construction engineering.In this thesis, on the basis of the related literature and make the scene of a construction site soil samples as a test object, by some basic mechanical test, indoor the theory analysis and numerical analysis method of combining the systematical study, and in the last, put two kinds of fitting effectiy model and the other two typical in hefei expansive soil creep soil sample data to contrast, In this article,the main research results and some conclusions are elaborated below.1. Through reading and study of domestic and foreign soil creep characteristics of literature, summarizes recent creep model and the research methods, and various methods of study made the introduction of the system are given, and Given its scope and the problems2. Studied the basic characteristics and causes of Hefei expansive soil,. expounded the expansive soil to a variety of discrimination. For the sake of explain expansive soil bilge shrink, author gives the two big factors, and through the remodeling test, analyze the relationship between the initial moisture content and flooding saturated water absorptiont. 3. First by uniaxial compression tests to determine the soil samples under uniaxial compression strength, and then use the principle of linear superposition of soil samples under uniaxial compression creep test, after five times grading loading test, draw the soil sample attenuation creep characteristics curve, and finally gives the analysis of data curve contrast.4. Make use of two commonly used check model formula and three components combination creep constitutive model for the statistics, author gives the test soil samples strain-time formula.The results show that Mesri creep experience model and Burgers element combination model are consistents with the soil creep properties.5. Compare the Mesri experience creep model and Burgers model calculated curve with another two typical weak expansive soil creep curve, the results show that in the low stress level, the Mesri model can reflect the soil deformation, but in the high stress levels,wo can use Burgers parts to assemble the model description.6. Finally, author uses the geotechnical engineering analysis software FLAC3D to analys the test soil samples, the results validate the validity of the models building, it can great practical value in engineering applications.