Abstract: The aim of this research is to explore the influence of freeze-thaw cycles on the physical-mechanical properties of mica quartz schist. Freezing-thawing test (0, 25, 50, 75, and 100 freezing-thawing cycles) was conducted on water-saturated mica quartz schist specimens and also conventional triaxial compression test was carried out under four levels of confining pressure. The dynamic elastic parameters, the failure mode caused by triaxial compression and the change rule of triaxial compressive strength were examined. Test results are presented as follows: 1) with the increase of freeze-thaw cycles, the triaxial compressive strength, dynamic elastic modulus, dynamic shear modulus and dynamic bulk modulus declined exponentially, while cohesion and internal friction angle decreased linearly. 2) Along with the proceeding of cyclic freezing and thawing, the boosting effect of confining pressure on the strength of samples were gradually weakened, whereas the deterioration effect of freezing-thawing cycles on the strength of samples became more prominent. 3) Under cyclic freezing and thawing, the triaxial compression failure pattern of mica quartz schist altered from tension failure to shear failure along schistose plane. 4) In addition, on the basis of the Jaeger failure criterion, a triaxial compressive strength prediction model for oblique schistosed mica quartz schist was established with the number of freezing-thawing cycle, the inclination of schistose plane, and confining pressure as control parameters. The prediction results were in good agreement with measured data.

Key words: mica quartz schist, freezing-thawing cycles, mechanical properties of rock, triaxial compression, schistosity plane, compressive strength