Multiscale mechanical analysis of Frozen Clay: Triaxial testing and discrete element modeling

Abstract

The macroscopic and microscopic mechanical characteristics of subgrade soil in cold regions play an important role in the stability of embankment engineering in cold regions. In this study, we conduct triaxial tests and isotropic loading-unloading tests on frozen clay in the cold region subgrade. The tests are conducted under different temperatures and confining pressures to obtain its macroscopic strength and deformation characteristics. Meanwhile, we establish a discrete element model of frozen clay based on the Discrete Element Method (DEM) to simulate conventional triaxial and isotropic loading-unloading tests, and analyze its mechanical characteristics from a microscopic perspective. The results of the study indicate that the strength and deformation of frozen clay are greatly affected by the cooling temperature and confining pressure. As the cooling temperature decreases, the cohesion of the specimen significantly increases, and the internal friction angle slightly increases, along with the elastic moduli. Under low confining pressure, the specimen exhibits significant volumetric expansion, while under high confining pressure, the specimen mainly undergoes volumetric contraction. Through discrete element numerical simulation, we obtain the microscopic mechanical characteristics of frozen clay, explain the “bulging” phenomenon of the specimen from a microscopic perspective, and verify the applicability of the flexible membrane. Meanwhile, the influence rules of various microscopic parameters on the mechanical properties of frozen clay are also obtained through a series of parameter calibration works.