Energy distribution and evolution of frozen silty clay at subzero temperatures under compressive loading

Abstract

Transportation geotechnical engineering in cold regions need to deal with many challenges related to the mechanical behavior frozen soil under thermal and mechanical loads. The deformation and failure of frozen soil under external loads is a complex thermodynamic process related to temperature, accompanied by the accumulation and dissipation of input energy. In order to reveal the influence of temperature on the mechanical behavior of frozen soil from the perspective of energy distribution characteristics and energy evolution law, uniaxial compression tests were carried out on frozen Genhe silty clay at different temperatures. The effect of temperature on mechanical indexes involving strength and deformation characteristics as well as energy indexes was investigated, and the quantitative relationship among elastic or plastic strain energy, stress or strain and temperature was established. The results demonstrate that the mechanical indexes of frozen Genhe silty clay linearly increase with decreasing temperature. With the decrease of temperature and increase of axial stress or strain, the absorbed elastic strain energy and dissipated plastic strain energy increases nonlinearly before the failure of specimens. When specimens are almost failure, the absorbed elastic strain energy remains nearly constant with increasing axial strain, but increases with a higher rate with increasing axial stress. Additionally, the dissipated plastic strain energy increases linearly with increasing axial strain, and dramatically increases with the increase of axial stress. With the temperature drops from −0.5 °C to −18 °C, the total strain energy at the peak strength accumulates to 160.145 J from 2.989 J, including the elastic part accumulates from 0.369 J to 5.668 J, and the plastic part increases from 2.620 J to 154.477 J.