Investigation of Energy Mechanism and Acoustic Emission Characteristics of Mudstone with Different Moisture Contents

Abstract

Characteristics of energy accumulation, evolution, and dissipation in conventional triaxial compression of mudstones with different moisture contents were explored. Stress-strain relations and acoustic emission (AE) characteristics of the deformation and failure of rock specimens were analyzed. e densities and rates of stored energy, elastic energy, and dissipated energy under different confining pressures were confirmed. e results demonstrated that the growth rate of absorbed total energy decreases with the increase of moisture content, indicating that the higher the moisture content is, the less the total energy mudstone samples absorb. e dissipated energy of the soaking sample, by contrast, has the first increase speed, and natural sample comes second at the beginning. When entering the crack stable development stage, the dry sample has the fastest growing rate of dissipated energy, meaning that dissipated energy used for crack propagation gradually decreases with the increase of moisture content. e AE signals significantly enhance at the initial compression stage and plastic deformation stage with the moisture content decreasing. e AE location events at the failure moment decrease as the moisture content increasing. e time that the maximum AE even rate appears is slightly lagged behind the macroscopic failure time, and the AE even rates increase with the decrease of confining pressure. e above results indicate that the water erosion process on rock reduces the cohesive energy and cohesive force, destroys the micromechanical structure, and minimizes the energy states of rock.

Energy Evolution and Damage Mechanism of Fractured Sandstone with Different Angles

“…Han et al [15] conducted a uniaxial compression test on sandstone with end fractures and found that the presence of cracks reduced the energy storage degree of their samples, but that the energy consumption parameters of rocks with cracks changed only slightly. Jiang et al [16] carried out triaxial loading test on mudstone and found that under the same confining pressure, the energy storage ratio of mudstone increased with the increase in water content, and the energy storage limit decreased linearly with the increase in water content. Meng et al [17] studied the acoustic emission characteristics and energy evolution characteristics of rock and concluded that the internal structure of rock and axial loading stress were the main factors affecting energy storage.…”

A model for rock dissipated energy estimation based on acoustic emission measurements

“…Although choosing different moduli will result in different quantization results of dissipative energy, this difference will not affect the variation trend of dissipated energy. The dissipated energy evolution characteristics similar to the loading and unloading tests can be obtained by this method (Jiang and Xu, 2018;Qin et al, 2019;Zhang et al, 2020a).…”

Water-bearing effect on mechanical properties and interface failure mode of coal–rock combination samples

“…Yu et al (2019) conducted uniaxial compression and creep tests on nine groups of red sandstone samples with different water contents, producing the quantitative relation of mechanical parameters of red sandstone versus water content. Jiang et al (2018b) performed triaxial compression tests on dried, natural, and saturated mudstone samples under different confining pressures and studied the mechanical properties and energy mechanism of mudstone with different water contents. Li et al (2021) conducted triaxial compression tests on raw coal with different water contents, based on elastic damage mechanics.…”