Abstract: The experiment of cycle of freezing and thawing has been conducted using the rock specimens from Tibet Yulong copper mine slope containing granite porphyry，quartzose sandstone and limestone. Experimental temperature has been controlled between -20 ℃ and 20 ℃ according to meteorological data and natural environment of the mine, volume, quality, uniaxial compressive strength, tensile strength, coefficient of freezing and thawing, and the change rule of decay rate of hard rocks have been measured and studied under the condition of water saturated state. The relation curve of freezing-thawing cycles and uniaxial compressive strength, tensile strength, coefficient of freezing and thawing have been fitted using Matlab software. The experimental results have been applied in the slope of the Tibet Yulong copper mine. Safety factors of the slope before and after freezing-thawing test have been calculated and compared by using strength reduction technique. This study can be used for similar mines.

Key words: open-pit metal mine, hard rock, freeze-thaw cycles, physical and mechanical property, strength reduction technique