Experimental study on mechanical properties of saline frozen silty sand

The triaxial compressive tests on saline frozen silty sand with the water content of 13% and Na2 SO4 content of 0. 5% were carried out at temperature of -6 ℃ . The confining pressures ranged from 0. 3 to 18 MPa. The results in- dicate that the influence of confining pressure on stress-strain curves is obvious at lower confining pressures,but with the increase of confining pressure,the influence gradually disappears;strength change with confining pressure can be divided into three stages:rapid growth stage of strength,slow growth stage of strength,decrease stage of strength;the in- itial tangent modulus E0 and the secant modulus at 50% strength E0. 5 changing with confining pressure can be divided into three phases,two modulus growth with confining pressure in phase 1 and phase 2,and the change rate is larger in phase 2,decrease in phase 3,but the change rate of E0. 5 is smaller under the whole scope of confining pressure,so E0. 5 can be regard as a constant at a larger range of confining pressure in the engineering design if it is used as the deform- ation index,but with E0 ,the effect of confining pressure must be considered.