Chaochao Zhang

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.

In this study, based on the background of massive freezing engineering in coastal strata, the thermal physical parameters and some freezing laws of soil were obtained through soil thermal physical tests and frozen soil frost heaving tests. When the freezing temperatures were −5°C, −10°C, −15°C, and −20°C, the frost heaving rates of the soil were 0.53%, 0.95%, 1.28%, and 1.41%, and the frost heaving forces of the soil were 0.37 MPa, 0.46 MPa, 0.59 MPa, and 0.74 MPa, respectively. In the range of test conditions, the frost heaving rate and the frost heaving force of the soil increased with the decrease of the freezing temperature, and the relationship was roughly linear with the temperature. The entire cooling process could be roughly divided into three stages: active freezing stage, attenuation cooling stage, and stability stage. The range of the frozen soil expansion did not increase linearly with the decrease of the freezing temperature, and there was a limit radius for the frozen soil expansion. A three‐dimensional finite element model was established to simulate the temperature field and frost heaving of the soil under the on‐site working conditions. The entire frost heaving process could be roughly divided into two stages. The calculated temperature values and the frost heaving force values were compared with the on‐site measured values, and the results verified that the numerical calculation could accurately reflect the temperature field and frost heaving law of the formation.