Research On Mechanics Characteristic And The Fractional Derivative Model Of Freezing Weak Expansive Soil

Due to the particularity of weak expansive soil and its harm to the project, most of the scholars on the room temperature weak mechanical characteristics of expansive soil was studied, but the weak expansive soil freezing of weak expansive soil mechanics characteristics of the study also "stretched" and the weak freezing expansion soil strength influence factor and the creep behaviour and failure characteristics of theoretical research is very weak, rich in weak expansive soil area of underground engineering by freezing construction method involved in, the original freezing and thawing soil mechanics can not be fully applicable, such as freeze weak expansive soil strength, creep deformation law and constitutive model. The fractional derivative theory and classical viscoelastic theory to describe the artificial frozen soil creep model of the theory of fractional order are deduced, and the previous research based on the theory of the optimization algorithm of the established fractional derivative Burgers model for global optimization. Do weak expansive soil test at Huainan area. The test on selected weak expansive soil samples arrangement, the uniaxial compressive strength test of artificial frozen soil under three factors and five levels, three temperature three loading coefficient under the condition of artificial frozen soil in uniaxial creep test. The main conclusions are:1. This paper in Anhui Science and technology developed at the University of WDT-100 permafrost of single axis test machines operating on freezing of weak expansive soil specimens of uniaxial compression test, obtained in different temperature, loading rate, water rate of three factors under uniaxial compressive strength changes the situation and builds the related model, finally through the orthogonal test, using orthogonal test and variance analysis are used to analysis of the freezing of weak expansive soil specimens subjected to uniaxial compressive strength of each factor sensitivity. Through a large number of swelling soil test, the relation between the influence factors and elastic modulus. The uniaxial stress-strain curve fitting comparison index function is more suitable for describing the freezing of weak expansive soil stress-strain relationship.2. Different solid creep model according to the connection between the basic elements it contains different elements and different, have different scopes. Selection of generalized Kelvin model and Burgers model comparison method that freezing of weak expansive soil of optimal uniaxial creep model, through the correlation coefficient of the two models can be derived, Burgers model fitting correlation coefficient was greater than the generalized Kelvin model, namely Burgers model fitting precision is excellent, can better simulate the freezing of expansive soil uniaxial creep curves.3. The fitting results of the fractional derivative Boggs model by fitting the experimental data and the results of the experimental data and compared with the results of the two models, although the expression equation can freeze the weak expansive soil creep characteristics, but found that the fractional derivative derived Boggs model can better reflect the artificial freezing creep the law of expansive soil, the correlation coefficient of the simulation results of the model equations are greater than 0.99, and as the loading time increases, the fitting curve is more close to the actual results, which can be obtained in the sample without being crushed, load case, when loading the selected time is longer, the results of model fitting can be infinitely close to with the test data. The equations of the model constructed by the fractional derivative form to simulate the artificial freezing expansion soil creep constitutive relation and complex geological environment by freezing method of special soil creep research provides a new method.