A Variety Of Triaxial Test Of Three Kinds Of Soil Nonlinear Constitutive Model Simulation

ABSTRACTIn recent years, with the development of economy and the progress of the scientific research, it takes out more requests in the aspect of the height and shape of buildings. Thus, it also plays a role in promoting the research on the soil. Since the 60’s of last century, soil constitutive model has been put forward. But today, our understanding of the foundation soil is still unknown, especially the soil constitutive model. It is a very difficult task, at present, to find a constitutive model to explain all the engineering condition. This paper based on the Duncan Chang model-- a kind of soil constitutive models – is a continuous study. Although, the Duncan Chang model is a nonlinear elastic model, it still has a lot of advantages, such as easy to determine the model parameters, and well to simulate the soil before the failure of the stress strain curve. Three kinds of Duncan Chang model and its improved model are involved in this paper. By using three model three axial compression test, different kinds of soils are simulated and analyzed. T The main conclusions of the work done in this process and related research are as follows:① I collect three tri-axial test data of three kinds of soils in different regions. Before simulating, through the Internet and books three kinds of soiled are collected. They are Beijing fine sand, a kind of floury soil in North China Plain and the Chongqing red clay. The contents of them include the detailed process of three axis test of soil, the results of stress and strain of the three axis test. They are representative. The results of these tri-axial test have been published in journals, and cited by many scholars.② In the paper, I introduce the basic theory of three kinds of constitutive models and related formulas. This paper presents how the Duncan-Chang model theory is put forward, its current status and future direction of development. The detailed basic model of three Duncan Zhang, which are E-ν model, E-GFD model and E-B model, is listed. Furthermore, I make a specific interpretation of the formula in each description.③ This paper gives a detailed description of the three axial test. It includes its object, method and process. Three-axial compression test method for soil is generally divided into stress controlled and strain controlled loading. In lots of the tri-axial test methods, most choose strain controlled loading method. Then, based on the theory, the parameters of Duncan-Chang’s formula is deduced; so is the stress and strain(including the normal strain and volume strain) associated with variable parameters. According to the results, it will predict the changes of the stress-strain relationship in the three axial compression test.④ This paper used for the FORTRAN language in the simulation program, which is based on the CALBR8 program. Some changes were made, the embedded model three Duncan- among them. In this paper, the process will be introduced in detail. It includes how the Duncan Chang model is used to simulate the laboratory tri-axial test.⑤ According to the collected data about tri-axial test of three kinds of soil, they will be simulated with three kinds of Duncan-Chang models, i.e. E-ν model, E-GFD model and E-B model. By means of calculation fitting parameters of three models, the corresponding value can be acquired. Through comparing the simulation results, it points out the similarities and differences between the three models that have their own advantages and disadvantages. It also proves the correctness of the process. It has certain theoretical significance of the study of relevant research results. It has reference value for the three constitutive models in engineering application.