Influence of Thermal and Mechanical Loading on Development of Microcracks in Granite

Compression‐induced crack initiation and growth in flawed rocks: A review

“…99 The results showed that the fracturing behavior of the granite specimens depends on not only the temperature but also the flaw array. More specifically, the granite specimens mainly exhibit tensile failure modes at 25-300 C, the brittle-ductile transition occurs at 300 C, the granite specimens experienced a mixed tensile-shear failure mode at 300-400 C, and they experienced a shear failure mode at T = 400-700 C. Besides, thermally induced microcracks in the granite mainly include intercrystalline cracks and intracrystalline cracks (Figure 8), which occur dramatically at T = 400-700 C. The amount of microcracks generated was found to be proportional to the heating temperature, which was in good agreement with the recent works by Li et al 90 Apart from high-temperature treatment, the freezethaw (F-T) treatment is also investigated by researchers. Wang et al 100 experimentally investigated the deterioration mechanism and fatigue fracturing evolution of granite with two pre-existing flaws experiencing F-T treatment.…”

“…Knowledge regarding the thermal-mechanical (TM) behavior of rocks is critical in deep mining, underground coal gasification (UCG), enhanced geothermal system (EGS), and reinforcement of rocks after exposure to fire. 90 The TM coupling mechanism is still the central issue for the failure of surrounding rocks in deep and the key coupling sequences needs more clear understanding. [91][92][93][94][95] For example, the maximum achievable temperature is 1000 C in UCG and 1300 C in nuclear self-storage.…”

Thermal cycling effects on the dynamic behavior of granite and microstructural observations

“…The specimens were kept at the target temperature for 3.0 h to ensure temperature uniformity in the specimen. The direction of all the granite specimens placed in the heating equipment was the same during the heating process (Li et al 2020b). Subsequently, in an air-conditioned room with a constant temperature of 25 °C, the specimens were naturally cooled to room temperature (for approximately 60 min at a cooling rate of 8.3 °C/min).…”

“…The literature shows that the dynamic modulus, resonance frequency, and quality factor of rock decrease as the temperature increases, but the damping ratio and specific damping capacity present an increasing trend (Ahmed et al 2018;Waqas et al 2020b). Generally, the degradation of the mechanical behavior of rock is induced by microdefects (Li et al 2020b;Wong et al 2020;Fan et al 2021). The decomposition of minerals, thermally induced cracks, and other defects can lower the dynamic mechanical strength of rock (Li et al 2016;Fan et al 2018).…”

Failure characteristics of shale after being subjected to high temperatures under uniaxial compression

“…Major rock engineering projects, such as deep mining, deep shale gas extraction, and the deep underground disposal of nuclear waste, involve the excavation and reconstruction of shale buried several kilometers deep (Thury and Bossart 1999;Gregory et al 2011;Monfared et al 2011;Vidic et al 2013;Vedachalam et al 2015;Murphy 2016;Wang et al 2018a;Wong et al 2020). In general, the temperature of the rock stratum increases with depth at a certain rate, indicating that shale in relevant engineering projects will inevitably be affected by the high-temperature environment (Owens 2013;Wong et al 2020;Li et al 2020). Taking deep shale gas extraction as an example, temperature is an important factor in deep reservoir reconstruction.…”