Study of the Influence of Temperature Rise on the Microstructure of Frozen Soil Based on SEM and MIP

In this study, the bearing capacity characteristics of warmed frozen soil under dynamic load were obtained by means of scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) test, and the microstructure change mechanism was evaluated. The lower the initial ambient temperature, the greater the strength of the warming frozen soil: the intensity of the $-20°\mathrm{C}$ warmed frozen soil was twice that of the $-5°\mathrm{C}$ soil. Through microscopic experiments, it was seen that the arrangement of pores in low-temperature frozen soil was more orderly than in high-temperature frozen soil. The pore distribution density in low-temperature frozen soil was large, the soil particles were more compact, the interparticle connectivity was good, and the pore area ratio increased with decreasing temperature. Under the condition of increasing temperature, the melting of ice crystal molecules in the pores and the combination of soil particles fill the large pores, so the pore volume decreases. The decrease in the pore volume was the key factor for the increase of soil accumulation deformation and the vulnerability of soil to destruction.