Abstract: Considering the characteristics of short diagenetic age and high intensity mining of Jurassic weak cemented sandstone in western China， the conventional triaxial compression tests， different unloading rates of confining pressure in triaxial compression tests and multi-stage triaxial tests were conducted to study the effects of confining pressure path on the strength and deformation. The results show that: the peak strength， residual strength， peak strain， elastic modulus and Poisson ratio depend on the confining pressure strongly， and the cohesion and internal friction angle of the sandstones in western China are lower than those of other sandstones. As the confining pressure increases， the failure mode transits from single plane fracture to complex multi-fracture. During the loading process， the change of confining pressure can remarkably affect the strength and the deformation characteristic by restricting lateral dilatation and increasing the angle of internal friction. The effect of unloading and loading confining pressure path on the mechanical parameters can provide references for the optimization of mining velocity and the support design of the surrounding rock masses.

Key words: calcareous argillaceous cemented sandstone, confining unloading rate, multi-stage triaxial loading, peak strength, deformation