Experimental study on effects of water content and temperature on mechanical properties of plateau soil

The orthogonal test of mechanical properties of plateau soil is carried out via a self-developed soil freeze-thaw cyclic shear equipment. The compression characteristics, freezing and frost heaving, and shear characteristics of soil affected by temperature and water content are studied. The results show that the normal displacement of soil samples during compression increases with the water content, and the relationship between compression value and normal stress can be described by hyperbolic model. The soil with different water content is frozen when the temperature drops from 0 ℃ to −12 ℃. The temperature of frost heaving of soil with 12% water content ranges from −3 ℃ to −2 ℃. The stress softening characteristics of soil become more and more obvious with the decrease of temperature, and the peak shear stress and residual shear stress are also the largest under negative temperature. The peak shear stress of soil near the optimum water content is the largest. The variation law of normal displacement of soil at −12 ℃ shows shear expansion characteristics under different test conditions, while the soil at 12 ℃ and 0 ℃ shows both dilatancy and shrinkage characteristics at low water content, and only shrinkage characteristics at high water content. The internal friction angle decreases with the content and temperature, and the cohesion decreases with the temperature, and reaches the maximum near the optimum water content.