INFLUENCE OF TEMPERATURE AND ICE CONTENT ON MECHANICAL PROPERTIES OF FROZEN ROCK-SOIL MIXTURE

Frozen rock-soil mixture is a special geotechnical material. Its mechanical behavior varies with temperature and ice content is still poorly understood. Direct shear tests were conducted to investigate the influence of temperature, ice content and normal stress on shear strength of rock-soil mixture. Results indicate that temperature, ice content and normal stress all have significant influence on shear strength of rock-soil mixture. For constant ice content and normal stress, shear strength of rock-soil mixture rises rapidly with temperature when the temperature is higher than-5℃.When temperature drops below -5℃,most free water is frozen and only small amount bond water is left,shear strength only has a slight increase with temperature. The shear strength of rock-soil mixture increases sharply when ice content is low. The shear strength reaches a peak value when the ice content is about 11% by weight. After that point, the shear strength has a slight decrease. Detailed research reveals that the cohesion of rock-soil material increases with ice content until the ice content reaches 11%, and then it tends to level off. But the internal friction angle decreases monotonously with ice content.The shear strength of frozen rock-soil mixture increases with the normal stress increasing. The plasticity of frozen rock-soil mixture increases under high normal stress.