Experimental Study on Creep Deformation of High-Temperature Frozen Soil Based on Microscopic Pores

The high-temperature frozen soil is prone to creep deformation under long-term load. In order to explore the influence of its internal pore structure on the creep deformation of high-temperature frozen soil, static triaxial creep tests under different temperatures, dry densities and axial stresses were carried out on the high-temperature frozen soil. At the same time, CT scanning and pore extraction were carried out on the air-dried triaxial samples after the creep test. The results show that: Avizo was used to conduct 3D modeling and pore extraction on CT scan images. After conducting pore equivalence analysis on the extracted pores using three different methods, it was found that sphere equivalent error was the smallest. Therefore, sphere equivalent was selected for microscopic pore analysis, and the pores were divided into four categories: 0~200 μm, 200~500 μm, 500~1000 μm and＞1000 μm. Under the given test conditions, the pore size of the sample is mainly distributed in the range of 200~500 μm, and the creep deformation is positively correlated with the number of pores with the pore size＞500 μm. The creep deformation increases with the increase of temperature, the decrease of dry density and the increase of axial stress, and the temperature, dry density and axial stress all have significant effects on the creep deformation and the number of pores with pore size＞500 μm. The number of pores with pore size＞500 μm increases with increasing temperature, decreasing dry density and increasing axial stress.