Mechanical Responses and Energy Evolution of Granite Subjected to Cyclic Loading, Thermal and Hydro-Mechanical Coupling
摘要
In deep underground engineering design and construction, it is essential to consider the coupling effects of multi-physics and cyclic loading on mechanical responses and damage mechanisms of rock. These coupling effects may cause rock failure and can further lead to significant engineering geological issues. Hence, multiple tests were performed to study the mechanical behaviors and energy evolution of granite. The findings demonstrate that the stress–strain curves subjected to cyclic loading exhibit hysteresis loops. Moreover, cyclic loading weakens the strength of granite and promotes microcracks. In addition, 150 °C and 450 °C are threshold temperatures. When the temperature is below 150 °C, the strength and deformability of granite are enhanced. Conversely, they are weakened, and thermal damage to granite is induced at higher temperatures. Cyclic loading enhances the weakening efficiency of high temperature on the strength of granite. A substantial decline in mechanical performance was observed at above 450 °C. Compared to high temperature, the impacts of pore water pressure on the mechanical behaviors are limited. At a pore water pressure of 80% of σ3, the granite exhibits a pronounced deterioration. However, cyclic loading reduces its weakening efficiency on granite. In contrast to the previous factors, the strength and deformability of granite are enhanced by confining pressure. Confining pressure effectively limits the weakening impacts of elevated temperature and pore water pressure on granite by restricting microcracks. Furthermore, it plays a dominant role in its coupling with cyclic loading.