Experimental Investigation of Mechanical Behavior of Sandstone with Different Moisture Contents Using the Acoustic Emission Technique

Abstract

The moisture content is a critical factor tightly related to rock deformation and its failure process since it leads to a significant change in the physicomechanical properties of rock during the underground engineering construction. As a result, engineering construction accidents take place frequently. To figure out the influence of the moisture content on the physicomechanical properties of water-bearing rock and then effectively avoid engineering accidents, multiple tests including the uniaxial compression test, Brazilian splitting test, and the acoustic emission (AE) test were carried out in this study. The experimental results showed that the water absorption rate of the sandstone gradually stabilizes after 5 h, and its uniaxial compressive strength, tensile strength, and elastic modulus all decline with the increase of the moisture content. Compared to the dry state of the sample, the reduction amplitudes of the elastic modulus, compressive strength, and tensile strength of water-saturated rock samples can reach up to 27.3%, 35.2%, and 38.1%, respectively. It indicates that the tensile strength is more sensitive to the softening effect of the moisture. Through the AE test, it can be found that the internal state of water-saturated rock samples is greatly changed; the compressive strength of rock samples drops, so the rock can be damaged after absorbing less energy. Thus, moisture shows a certain softening effect on rock. The research results are expected to provide a basis for underground engineering construction and rock fracture and failure.

Effects of changing water content of clay-content rocks on field cutter consumption rate of roadheaders: a case study of porous ignimbrites

“…Also, the average decreases in UCS and BTS values are obtained as 46.34% and 51%, respectively. Many previous studies report that increased water content reduces rocks' strength, similar to this study (Li et al 2012(Li et al , 2020Wong and Jong 2014;Zhou et al 2016). Hawkins and McConnell (1992) reported that the difference between UCS values obtained in dry and saturated conditions for the clay-rich Cretaceous Greensand was 78%.…”

Experimental Study of Confined-Pressure Soaking on Sandstone Damage-Fracture Characteristics Using Acoustic Emission and Energy Dissipation

“…According to the description of related literatures, the evolution of AE events in the whole loading process for conventional soaking samples could be divided into quiet period, stable growth, significant growth and sudden change stages [33,41], which is consistent with the change trend of CPS. The growth of moisture contents inhibits the generation of AE signals to a certain extent, and meanwhile delays AE excitation time [19,42].…”

“…Under three soaking conditions, the modif effect of low-medium moisture content on rock samples is mainly shear failure [ For high moisture content, the specimens subjected to CPS and natural soaking ten homogeneous in modification; their fracture modes are consistent, showing longit tensile cracks and local fragments [35,36]; this shows the reliability of the experim The failure and fracture modes of CPS and natural soaking rock samples are similar with the increase in moisture content. Under three soaking conditions, the modification effect of low-medium moisture content on rock samples is mainly shear failure [33,34]. For high moisture content, the specimens subjected to CPS and natural soaking tend to be homogeneous in modification; their fracture modes are consistent, showing longitudinal tensile cracks and local fragments [35,36]; this shows the reliability of the experimental results of the CPST effect.…”

Degradation of Strength and Stiffness of Sandstones Caused by Wetting-Drying Cycles: The Role of Mineral Composition

“…Weakening Mechanism for Strength Reduction Induced by WD Cycles. It is extensively shared that the presence of water plays a dominant weakening role on rock strength and stiffness due to physical-chemical-mechanical waterrock interactions [19,[30][31][32][33][34]. Some water-weakening effects will be vanished when the rock is dried again, but some are not and lead to irreversible damage of rock structure [35].…”