Abstract: To obtain the effects of varied saturations and confining pressures on mechanical properties of sandstone, the triaxial tests on sandstone samples from Balikun mine were performed under varied saturation and confining pressures. Then the modulus, peak strength and residual strength were obtained. The effects of varied saturations and confining pressures on mechanical properties of Balikun’s sandstone were analyzed; and the results show that: (1) With confining pressure increasing, the sandstone modulus increases, and the relationship between confining pressure and modulus follows linear form. With saturation increasing, the modulus decreases. The uniaxial compression modulus of saturated sandstone decreases 50.9%. The relationship between saturation and modulus follows linear or negative exponential form. (2) With saturation increasing, the peak strength decreases. The uniaxial compression strength of saturated sandstone decreases 44.2%.The relationship between saturation and peak strength follows natural logarithm form. (3) The effects of confining pressure on residual strength can be described by degradation index. The relationship between degradation index and confining pressure of Balikun sandstone follows negative exponential form. With saturation increasing, the residual strength decreases. (4) With confining pressure increasing, the effects of varied saturation on modulus, peak strength and residual strength decrease. (5) Less than 60% of saturation, variation of saturation greatly influences the modulus and peak strength. Larger than 60%, the effects decrease. Less than 80% of saturation, variation of saturation greatly influences residual strength.

Key words: Balikun sandstone, modulus, peak strength, residual strength, triaxial tests, saturation