EXPERIMENTAL STUDY ON THE COMPRESSIVE AND SHEAR STRENGTH OF SEASONAL FROZEN SOIL IN DONGNING AREA, HEILONGJIANG PROVINCE

Taking the soil layers including silt, silty clay and clay in Dongning area of Mudanjiang City as the research object, collecting and selecting the undisturbed soil samples with different moisture content and soil texture, the paper studies the physical and mechanical properties of soil such as uniaxial compressive strength and triaxial shear strength under different negative temperature conditions. The results show that the uniaxial compressive strength of undisturbed soil increases with the decrease of temperature after freezing under different negative temperature conditions; the cohesion increases exponentially with the increase of moisture content; while the internal friction angle first increases and then tends to be stable with the increase of moisture content. Under the negative temperature conditions, -20℃ is the change point. When the temperature is below -20℃, the uniaxial compressive strength of frozen soil first increases and then decreases with the increase of moisture content, and the cohesion increases with the decrease of freezing temperature; At -10℃ or -20℃, the internal friction angle of frozen soil follows a similar rule, no obvious change with the fluctuation of water content, and the shear strength of frozen soil increases with the decrease of freezing temperature; When it is above -20℃, the uniaxial compressive strength of frozen soil increases with the increase of water content, and the cohesion does not increase with the decrease of freezing temperature, while the internal friction angle increases with the decrease of freezing temperature, and the shear strength of frozen soil gradually increases and tends to that of ice with the decrease of freezing temperature.