Numerical Investigation on the Freezing Evolution Process of Rock Mass at Sub-zero Temperature

Abstract

ABSTRACT The freezing and thawing of soils have been extensively researched, but little effort has been devoted to addressing the freezing evolution process of rock mass. In this paper, a novel approach for the multi-physics constitutive models considering the change of the elastic modulus and linear expansion coefficient were developed and employed. The proposed coupling model was successfully integrated into Abaqus to simulate the freezing process of rock mass with reasonable results. The simulation results indicate that the pore water will gradually freeze into the pore ice, which will fill the pore space of the sandstone, so that the overall volume of the sandstone increases significantly. Moreover, combined with previous physical experimental studies, it also can be concluded that low temperature freezing can significantly improve the pore structure and mechanical properties of frozen sandstone. Especially, the increased absolute porosity may not be recovered after the ice lenses melts, which may cause serious irreversible frost damage to the internal structure of the sandstone. The finite element module can be used to predict the change of temperature, unfrozen water content, ice lens content, pore structure and volumetric deformation of rock mass during freezing, which can be used to accurately evaluate the effect of frost heave on the internal structure of rock mass. The study provides a theoretical basis and reference for the design and maintenance of cold region engineering and cryogenic reservoir stimulation.