Strength Weakening and Energy Mechanism of Rocks Subjected to Wet–Dry Cycles

Based uniaxial compression tests of altered granite, the weakening laws of rock strength and energy mechanism of rock failure for altered granite subjected to wet–dry cycles are analyzed. Results show that: (1) with increasing number of wet–dry cycles, the rock weakening coefficient and damage variables increase gradually. The maximum weakening coefficient of altered granite-1 was 50.22%, and the damage variable was up to 63.84%. The maximum weakening coefficient of altered granite-2 was 43.22%, and the damage variable was up to 44.00%. (2) The total energy of rock increases gradually with the number of wet–dry cycles. Elastic strain energy in the rock increases first then decreases. The energy storage limit decreases gradually, showing a linear or exponential relationship with the number of wet–dry cycles. (3) The rock damage energy mechanism under wet–dry cycles is obtained via the rock dissipation energy. The rock dissipation energy increases gradually as the number of wet–dry cycles increases. Wet–dry cycles causes irreversible damage to the rock internal structure.