Abstract
To study the long-term stability of the large-scale freezing project, the longest subway connecting channel constructed by the artificial freezing method in China is taken as the background. The uniaxial compressive strength test, triaxial shear test, and triaxial creep test of artificial frozen soil under different temperatures were carried out by using the MTS 370.25 mechanical testing machine. A series of triaxial creep tests for artificial frozen soil under different stresses and temperatures were carried out. Based on the creep test results, a fractional-order constitutive model of frozen silt with sand was proposed. Comparing the calculated results with the tested ones, it is found that the proposed fractional-order model can simulate the properties of frozen silt with sand very well. Compared with the other creep models of frozen soil, the proposed model here has higher accuracy and strong stress sensitivity. Through the simulation of the connecting channel construction and comparison with the observed data in site, the effectiveness of the model is verified, which further verifies that the model has important guiding significance for the freezing project.
Highlights
Frozen soils are compound materials consisting of solid mineral particles, ice crystals, liquid water, and gaseous inclusions
It is well recognized that frozen soils show nonlinear viscoelasticplastic behavior. erefore, in some projects, for example, the superlong freezing connecting passage project studied in this paper, linear approximations cannot be used. e strength and creep characteristics of frozen soils are the most important mechanical properties for the engineering construction
In order to meet the needs of the application of engineering activities, a series of experimental studies on the mechanical properties of frozen soil had been conducted [1,2,3,4,5,6,7,8,9]
Summary
Frozen soils are compound materials consisting of solid mineral particles, ice crystals, liquid water, and gaseous inclusions. E strength and creep characteristics of frozen soils are the most important mechanical properties for the engineering construction. Mengke et al [35] conducted a series of triaxial creep tests on warm frozen silts, and they established a fractional-order rheological element model based on the creep test results Most of these studies show that the creep curves only include primary and secondary creep stages under different stress levels and ignore the influence of temperature effect. From the test results in this paper, the creep curves can be distinguished by three stages clearly when the stress level exceeds the stress threshold, and the influence of temperature effect will be involved in the characteristics of frozen soil and constitutive model. The test data of frozen soils at different temperatures and test conditions were used to verify the proposed model, and it is found that the proposed fractional-order model can simulate the properties of frozen silt with sand very well and has a great engineering value and realistic significance
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