Study of Strength Damage Characteristics of Moderately Weathered Granite under Wetting-Heating Cycles

The purpose of this study is to reveal the mechanism underlying the strength damage of granite in humid and hot environments. Uniaxial compression tests and Brazilian splitting tests were carried out on moderately weathered granite specimens experienced different forms and numbers of wetting-heating cycles. The effects of cooling-heating cycles at constant humidity, drying-wetting cycles at constant temperature, and hot drying-cool wetting cycles on the uniaxial compressive strength, elastic modulus, splitting strength and damage factor of moderately weathered granite were analyzed. The results show that: The uniaxial compressive strength and elastic modulus of moderately weathered granite exhibit exponential attenuation with increasing number of wetting-heating cycles. After 30 cooling-heating cycles, drying-wetting cycles and hot drying-cool wetting cycles, the reductions in uniaxial compressive strength are 13.63%, 19.76% and 21.54%, respectively, and those in elastic modulus are 42.78%, 50.34% and 53.78%, respectively. The splitting strength decreases linearly with an increase in wetting-heating cycles. After 30 cooling-heating cycles, drying-wetting cycles and hot drying-cool wetting cycles, the decline amplitude of the splitting strength are 38.59%, 65.65% and 71.53%, respectively. Based on damage analyses, it is found that the hot drying-cool wetting cycles that consider the coupling of temperature and humidity changes have the most significant damaging effect on the strength of moderately weathered granite, and the drying-wetting cycles have the second significant damaging effect. Compared to the uniaxial compressive strength, the splitting strength is more vulnerable to the damaging effect of long-term wetting-heating cycles.