Abstract: Uniaxial compression tests were carried out on altered rocks under different temperature cycles to investigate the damage patterns of mechanical properties under cyclic temperatures. Results show that the mechanical properties of the altered rocks are obviously weakened by effects of temperature cycles. With the increase of temperature cycle times, uniaxial compressive strength and elastic modulus decreased and the relationships between them and temperature cycles obeyed exponential distribution. The sensitivity of different rocks to the temperature cycles is different, and the higher the degree of alteration of weathering is, the stronger the sensitivity is. Uniaxial compressive strength is more vulnerable to temperature than elastic modulus does. The cumulative damage values of uniaxial compressive strength reached 35.69% and elastic modulus 29.57% after 20 times of temperature cycles. The relationships between damage values of mechanical properties and the temperature cycles also obeyed exponential distribution. Results of electron microscope scanning revealed that cracks were generated in rocks under cyclic temperatures, mineral composition and internal structure changed, connection force between the lattice was weakened and mechanical properties were changed.

Key words: altered rock, cyclic temperature, mechanical test, damage characteristics, scanning electron microscope