Uniaxial Compressive Modulus Research Articles

Multi-scale Experimental Investigations on the Deterioration Mechanism of Sandstone Under Wetting–Drying Cycles

The repeated wetting–drying (WD) cycles can cause the deterioration of rock and thus affect the service performance of the related rock engineering, e.g., the crushed-rock embankment and the reservoir. The study comprehensively investigated the deterioration mechanism of sandstone under the WD cycles based on a series of multi-scale experiments, including the microstructure, the meso–micro pore characteristics, and the macroscopic physical and mechanical properties. The results indicate that the content of dissolved minerals and the permeability are two key factors that determine the deterioration effect caused by the WD cycles. During the WD cycles, the pore size range of sandstone becomes wider due to the formation of new small pores and the connection of original pores. Thus, low-density area forms within the samples, which causes the increasing of density dispersion. The structure deterioration weakens the physical and mechanical properties of the samples. The ultrasonic test indicates that the decreasing rate of the P-wave velocity is larger than that of the S-wave velocity, especially in the first 5 cycles. Besides, the exponential equations of uniaxial compressive strength and elastic modulus with the number of WD cycles are established to describe the deterioration of mechanical characteristics.

Estimation of Coal and Rock Mechanical Properties for Numerical Modelling of Longwall Extraction

Reliable estimation of coal and rock mechanical properties at field scale is a prerequisite for numerical modelling of rock behaviours associated with longwall extraction. This paper describes a systematic approach from data collection, laboratory testing to rock mass properties derivation for simulation of longwall extraction, taking two longwall panels at Quang Ninh coalfield in Vietnam for example. The mechanical properties are verified through comparison with published data of the field, indicating close agreements. A simple numerical model is further developed to demonstrate the proper use of the obtained data. The simulation suggests that the ratio of model length to excavation length should be in the range of 2.5–5; uniaxial compressive strength, deformation modulus and tensile strength can be reduced by a factor of 5.0, 2.13 and 2.0, respectively; and a calibration and validation process must be performed to match in-situ longwall’s behaviours. The approach can be applied for derivation of reliable rock mass properties for numerical simulation of underground excavations.

Effects of cyclic wetting-drying on the mechanical behavior and improved damage model for sandstone

The degradation of rock mechanical behavior after cyclic wetting and drying could affect the stability of rock slope, embankment, and tunnel significantly. A series of tests were first conducted on sandstone collected from a reservoir bank slope. The results showed that the mechanical parameters (including tensile strength, uniaxial compressive strength, elastic modulus, and internal friction angle) decrease as the cyclic number of wetting and drying increases. Then, a damage variable, which can consider the combined influence of cyclic wetting-drying and loading, was first proposed based on test results. Further, an improved damage model, which considers the effect of cyclic wetting-drying on internal friction angle and the nonlinear deformation characteristics in the fissure closure stage, was established with statistical damage mechanics. The determination method for the parameters in the proposed damage model was also introduced. Finally, the effectiveness of proposed model was verified by comparing with experimental data. The verification indicates that the results from the improved model agree well with test results, and the improved model can enhance the prediction accuracy over the original model.

Numerical study on strength and failure characteristics of rock samples with different hole defects

In a rock mass, holes of various sizes and geometries naturally occur, which in turn can affect the mechanical properties of the rock mass. These defects often cause engineering problems in subsurface construction. In this study, PFC2D was used to perform uniaxial compression tests on a rock mass containing ten different types of hole defects to analyze their failure behavior and mechanical properties. Four failure modes were determined, and crack propagation and stress field evolution were studied. The results show that the hole defect reduces the uniaxial compressive strength, peak strain, and elastic modulus of a rock mass. Also, these defects accelerate the generation of cracks and promote the destruction of the rock. The failure modes can be classified as Y-type, inverted Y-type, upper left to lower right type, and upper right to lower left type. Before cracks are generated, the compressive stress concentration area is located on the left and right sides of the hole and distributed as a butterfly shape, and the tensile stress concentration area is located in the upper and lower parts of the hole. A zone where stress is decreasing is located near the tip of the tensile stress triangular area. The magnitude and concentration area of compressive and tensile stresses are greatly affected by various hole geometries. Finally, the maximum principal compressive stress decreases instantly after a crack coalesces. Overall, the hole shape has a noticeable influence on the stress distribution surrounding the hole, and a hole defect reduces the degree of failure of a rock mass.

Effect of Acidic Solution on Mechanical Properties and Mesoscopic Structure of Hard Sandstone

The present study envisaged the effects of leaching solution on the mechanical properties of stope surrounding rock in in situ blasting leaching of sandstone type uranium deposit. Experiments were performed using uniaxial compression tests and SEM observation of sandstone samples after soaking in the H2SO4 solution with pH 1, 2, 3 and 4 for 5, 10, 20, 30 and 40 days. The results showed that at pH 1, the solution levels increased slowly and steadily all the time, and for other pH solutions the levels increased rapidly in the first 5 days with a slow subsequent increase. The pH 2 solution showed reddish brown coloration in varying degrees, since it provided good conditions for Fe(OH)3 precipitation. It is suggested that the pH value of leaching solution should be controlled within 1.5–2.0 during the regular leaching period of ore pile, and then adjusted to 2.0–2.5 after the leaching process based on the forming conditions and uranium-adsorbing characteristic of the Fe(OH)3 colloid. Furthermore, with the increase in the solution pH, the mass change rate of the sandstone sample decreased. The uniaxial compressive strength and elasticity modulus of sandstone samples decreased with an increase in the soaking time and a decrease in the pH. After soaking in acid solution (pH < 4) for 40 days, the uniaxial compressive strength of sandstone decreased by about 50%, which needs to be considered in the design of pillar size. Compared to the samples in the natural state, the failure sound of sandstone treated with acidic solution weakened, accompanied by more debris and cracks, and the failure mode changed from brittle to less brittle. SEM analysis showed that, at the same soaking time, the stronger acid corrosion resulted in a looser surface structure and the larger diameter of the corrosion pore in the sandstone sample. After soaking in the same solution, there was no significant difference in the surface structure and pore diameter of the sandstone sample with an increase of soaking time.

Improving coal seam permeability and displacing methane by injecting liquid CO2: An experimental study

To study coal permeability after the coal has been treated with liquid CO2, coal samples were first treated in a purpose-built liquid CO2 soaking system. After samples were treated in this system, cracks on the samples’ surfaces, the coal’s pores structure, and its mechanical properties were studied using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and uniaxial compression tests. The results show that large and complex fracture networks are generated on the surface of the treated samples. During liquid CO2 soaking, some of the micropores are enlarged and transformed to mesopores and this leads to adsorption and seepage pores becoming connected. Compared with untreated coal, the uniaxial compressive strength and elastic modulus of the treated coal samples decreased by 20.3%–44.6% and by 8.7%–43.5%, respectively. An experiment on methane displacement by CO2 showed that the CH4 concentration in the displaced gas for the same displaced gas flow rate increased in tandem with the gas injection pressure. At the same injection pressure, the CH4 concentration decline increased in tandem with the displacement flow rate.

English

Magnetic susceptibility and mechanical properties of rocks in a typical basement complex Southwestern Nigeria were correlated with the aim of establishing empirical equations relating the two parameters and evaluate the parameters as related to its competency in hosting civil structures. A total of thirty rock samples were taken across the geology of the area and subjected to mechanical properties determinations. Magnetic susceptibility measurements were carried out on in-situ fresh rock outcrops and it ranges from 2.1 × 10-4 to 9.5 × 10-4. This signifies the amount of iron content in the rocks and its level of induration. The values of uniaxial compressive strength (UCS), Young’s modulus (E), shear modulus (µ), bulk modulus (K) and Poisson’s ratio (N´) ranges from 49 - 107 MPa, 1003 - 3321 MPa, 416 - 1310 MPa, 707 - 2728 MPa and 0.232 - 0.316, respectively. The cross plots of the mechanical parameters with the magnetic susceptibility exhibit a direct linear relationship. The relationship shows a good correlation with coefficient of correlation (R) ranging from 0.60 to 0.85 for uniaxial compressive strength, bulk modulus and Poisson’s ratio. The magnetic susceptibility relationship with shear and Young’s Modulus are relatively weak with coeffecient of correlation (R) of 0.44 and 0.47, respectively. This implies that, magnetic susceptibility measurement may not be reliably applicable in determination of the stiffness of rocks and the rate of resistance of rocks to prevailing shearing loads. The validation results show that, reliable mechanical properties of rocks can be estimated from magnetic susceptibility measurements using the established empirical equations. Key words: Magnetic, susceptibility, mechanical, properties, rocks.

A hybrid computing model to predict rock strength index properties using support vector regression

The uniaxial compressive strength (UCS) and elasticity modulus (E) are two of the most quoted rock strength parameters in engineering application. Due to approved technical difficulties indirect measurements, the tendency for determining these parameters through predictive models using simpler and cheaper tests in practical oriented applications have widely been highlighted. In this paper, a new hybridized multi-objective support vector regression (MSVR) model integrated with the firefly metaheuristic algorithm (FMA) was developed to touch upon a computational method in rock engineering purposes. The optimum internal parameters were adjusted through parametric investigation using 222 physical and mechanical rock properties corresponding to a variety of quarried stones from all over Iran. The accuracy and robustness of models were evaluated using different error indices, the area under curve for receiver operation characteristics (AUCROC) and F1-score criteria. Comparing to MSVR, the predictability level of UCS and E showed 8.35% and 5.47% improvement in hybrid MSVR-FMA. The superior and more promising results imply that hybrid MSVR-FMA as a flexible alternative can be applied for rock strength prediction in designing of construction projects. Using tow sensitivity analyses, the point load index and P-wave velocity were distinguished as the main effective factors on predicted UCS and E.

Effect of initial suction on the stiffness and strength of densely compacted Gaomiaozi bentonite

Knowledge of the mechanical properties of compacted bentonite is essential to assessing the performance of an engineered barrier system in a high-level radioactive waste repository. In this study, direct shear tests and uniaxial compression tests were conducted on compacted Gaomiaozi bentonite with a dry density of 1.7 g/cm3 to investigate its stiffness and strength characteristics at various initial suction levels. Specimens were found to exhibit brittle failure within an initial suction range of 11–223 MPa. The peak shear strength and shear modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 126 MPa. The residual shear strength was found to increase with increasing initial suction within 11–223 MPa. The uniaxial compressive strength and elastic modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 62 MPa. Models were developed to predict the stiffness and strength of the specimens as a function of the initial suction and effective stress parameter (χ). For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, using the degree of saturation (Sr) and effective degree of saturation (Se) in place of χ produced the same trends which diverged from the test results at initial suction levels lower than 12 MPa and higher than 126 MPa. However, using Sr and Se in place of χ reasonably reproduced the residual shear strength within an initial suction range of 11–223 MPa. In contrast, using (Sr)α (Sr raised to an exponent α) in place of χ reproduced the test results well. For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, the simulations required a value of 2.4 for the α. For the residual shear strength, the best value of α was 1.0. Based on the testing method and model approach developed in this study, the evolution of the stiffness and strength of compacted bentonite along wetting and drying paths can be further explored.

Material preparation and mechanical properties of transparent soil and soft rock for model tests

To investigate the optical and mechanical properties of transparent soil, experimental research was conducted and the microscopic structure was analysed with the help of a scanning electron microscope, the refractive indices of the transparent soil under different void ratios were obtained, observing the microscopic characteristics transparent soil. In addition, a consolidation test and a shear test were conducted to elucidate the e–p relationship and shear parameters of the transparent soil. On this basis, a material similar technique to the transparent soft rock was prepared and uniaxial compression tests were conducted to determine the uniaxial compressive strength and elastic modulus of the transparent soft rock under different consolidation pressures. The stress–strain curve of the transparent soft rock can be divided into three stages, with the increase in consolidation pressure, both the uniaxial compressive strength and elasticity modulus of the transparent soft rock increased significantly. These findings are of theoretical and practical significance, which can provide references for model tests on transparent soils used in geotechnical engineering.

Experimental research on proportioning of similar materials for coal and gas outburst simulation

Coal and gas outburst similar materials are the basis for coal and gas outburst simulation experiments. The study of similar materials helps to more accurately reduce the phenomenon of coal and gas outburst. By using the pulverized coal, sodium humate and river sand as raw materials, through the orthogonal experimental design, outburst coal similar materials are studied, and the physical mechanics such as the uniaxial compressive strength, elastic modulus and density of similar materials under different mixing ratios are obtained. The results show that under the molding pressure of 20MPa, the uniaxial compressive strength range is 1.335 to 2.527 MPa, the elastic modulus range is 117.45 to 302.00 MPa and the density range of similar materials is 1.308 to 1.438 g/cm3. Sodium humate content and pulverized coal ratio are the main influencing factors controlling the uniaxial compressive strength and elastic modulus of similar materials, while river sand content is the main influencing factor controlling the density of similar materials.

Experimental Study on Mechanical Properties of Anchored Rock-Like Material with Weak Interlayer Under Uniaxial Compression

The weak interlayer in rock mass is an important factor affecting the stability of geotechnical engineering. In practical engineering, bolt is widely adopted to reinforce the rock mass with weak interlayer. In order to investigate the anchorage mechanical properties of rock with weak interlayer, we employed cement mortar and gypsum to simulate rock and weak interlayer and then conducted a series of uniaxial compressive experiments of anchored rock-like material. Our experimental results show that: (1) the weak interlayer significantly increases the heterogeneity and anisotropy of rock mass, resulting in many fluctuations on the stress–strain curve. Compared with the non-bolted rock, the stress–strain curve of anchored rock exhibits stronger ductility; (2) for the non-bolted rock with inclined interlayer, the uniaxial compressive strength, elastic modulus and Poisson's ratio decreases gradually with increasing interlayer inclination. (3) The influence of the dip angle of the weak interlayer on the failure modes of rock mass with weak interlayer is more notable than anchorage angle. The failure modes of anchored rock with weak interlayer can be divided into four patterns: splitting failure of weak interlayer, splitting failure of both weak interlayer and rock, composite failure of weak interlayer splitting and rock shear fracture as well as composite failure of weak interlayer splitting and rock-interlay interface shear slip.

Uniaxial Compression Fractal Damage Constitutive Model of Rock Subjected to Freezing and Thawing

Mechanical properties of the rock in the cold regions are often affected by freeze-thaw cycles and loads. It is of great theoretical significance and engineering value to establish a uniaxial compression damage constitutive model of the rock under freeze-thaw cycles that can reflect the relationship between macroscopic and mesoscopic structural damage. In this paper, macroscopic and mesoscopic methods are combined with statistical methods to quantitatively analyze the damage degree of rock under freeze-thaw cycles and loads. Combined with the fractal features of the macroscopic image of the section, a fractal damage constitutive model considering the residual strength of rock is established. In addition, the model is subsequently verified by the experiment. The experiment shows that the mechanical properties of rocks subjected to freeze-thaw cycles and loads are determined by freeze-thaw damage variables, load damage variables, and their coupling effects. As the number of freeze-thaw cycles increases, the uniaxial compressive strength and elastic modulus of rocks decrease, and peak strain increases. By using the fractal dimension of the compression fracture surface as a bridge considering the residual strength of the rock, the constitutive model can better reflect the compaction stage, elastic deformation stage and plastic deformation stage of the uniaxial compression process of the freeze-thaw rocks.

Temperature-induced deformational responses and microstructural alteration of sandstone

The high-temperature response of rock is quite useful for successful exploration and exploitation of various conventional as well as unconventional energy systems such as underground coal gasification, and geothermal energy, where the associated rocks are exposed to various temperature and pressure conditions. In this study, we have investigated the effect of temperature and thermal alteration of an Indian sandstone. An investigation using acoustic emission, digital image correlation through ARAMIS, micro-computed tomography (CT) techniques and thermogravimetric analysis was performed to study the mechanical responses of the sandstone with increasing temperatures. The results indicate that uniaxial compressive strength (UCS), tensile strength and elastic modulus of sandstone reduced significantly and aligned in an overall decreasing trend with increasing temperatures. The maximum and minimum UCS of sandstone were obtained at 400 °C and 700 °C, respectively. Acoustic emission (AE) responses of the sandstone indicated an early crack initiation and crack damage for high-temperature treated specimens. The deformation was further analysed using the ARAMIS digital image correlation technique, and strain levels were visually quantified that exhibited a widespread distribution of higher strain for thermally-treated specimens at 700 °C. Microstructural thermal damage and different pore-characteristics were studied using micro-CT techniques that provided valuable information about the connected and non-connected pores of the sandstone and their evolution with increasing temperatures. The outcomes suggest a heat-induced increment in porosity by nearly 40 percent upon heating the samples from 25 °C to 600 °C, which can be attributed due to the opening of new cracks that stimulated structural damage.

Numerical investigation of micro-cracking behavior of brittle rock containing a pore-like flaw under uniaxial compression

Pore-like flaws, which are commonly encountered in brittle rock, play an important role in the engineering performance of structures constructed in or on rock. Experimental and numerical investigations of micro-cracking mechanism of rock containing a pore-like flaw can enhance our knowledge of rock damage/failure from a microscopic view. In this study, the influences of a two-dimensional circular pore-like flaw with respect to its diameter and position on the strength and micro-cracking behavior of brittle rock under uniaxial compression are numerically investigated. The results reveal that the strength and elastic modulus are significantly affected by the diameter and position in the pore. The uniaxial compressive strength and elastic modulus of the numerical model with a pore diameter of 15.44 mm located in the center of the model are found to decrease by 58.6% and 56.4% respectively when compared with those of the intact model without a pore. As the pore position varies while the porosity remains unchanged, the simulated uniaxial compressive strength and elastic modulus are also found to be generally smaller than those of the intact model without a pore. When a pore-containing numerical model is loaded, the micro-cracks are found to mostly initiate at the top and bottom of the pore, due to the local tensile stress increase. The simulation results of the early-stage micro-cracking process and stress distribution are in a generally good agreement with the analytical solution obtained from the Kirsch equations. The grain-based model used in this study can not only study the crack initiation on the boundary of the pore but also provide a convenient means to analyze and visualize the temporal and spatial micro-cracking process after the crack initiation, which accounts for the variations in the simulated strength and modulus satisfactorily from a micro-cracking view.

Effects of recycled aggregate composition on the mechanical characteristics and material design of cement stabilized cold recycling mixtures using road milling materials

Road milling materials, including the reclaimed asphalt pavement (RAP) and the reclaimed cement stabilized base-course (RAI), have been widely used as the recycled aggregates (RA) to prepare cement stabilized cold recycling mixtures (CSCRM) used in highway rehabilitation. However, there are few studies on the effect of RA composition (RAP and RAI proportion in RA) on the pavement performance of CSCRM. In this study, therefore, a total of forty-two groups of CSCRM are prepared in the case of different RA contents, RA compositions and cement contents. The investigation of mechanical characteristics (unconfined compressive strength, splitting strength and uniaxial compression modulus) of CSCRM reveals the effect of RA content, RA composition and cement content. The RA content, RA composition and cement content play an important role in the mechanical properties of CSCRM. The strength mechanisms of CSCRM are revealed via the micro-interface characteristics for based on SEM-image. Finally, the recommended material compositions of CSCRM are put forward and verified via durability tests (fatigue tests, dry-shrinkage tests and water-erosion tests). Results show that the recommended CSCRMs present a better overall performance.

Physico-mechanical Behaviors of Granite Under Coupled Static and Dynamic Cyclic Loadings

The stress distribution around constructions in deep rock can be modified by dynamic disturbances, such as earthquakes. For this, we proposed a new loading method applied to granite sample under coupled static and dynamic cyclic loading (CSDCL) condition. The variations in P-wave velocity, gas permeability, and mechanical properties of granite before and after CSDCL are revealed. It shows that with increasing axial static stress, the dynamic cyclic loading amplitude and cycle number, P-wave velocity, uniaxial compressive strength (UCS) and elastic modulus decrease, whilst the permeability and Poisson’s ratio increase. It seems that variations in those parameters have a close relation with the exciting frequency. In this case, CSDCL is applied for crack development along the axial direction in the rock samples, and subsequently results in degradation of mechanical properties, delay of P-wave propagation, and increase of the transport paths. The results show that the permeability and Poisson’s ratio are likely to be more sensitive to the CSDCL, in particular under the axial static stress. The empirical relationships of the P-wave velocity with permeability, UCS, and elastic modulus are established for a pragmatic monitoring purpose. From design point of view, we have established the relationships of the disturbance factors to damage variable. Then the correlations of the damage variable to permeability, UCS, and elastic modulus are analyzed. The testing results in this context could facilitate our understanding of rock stability upon excavation subjected to dynamic disturbances.

Experimental Study on Properties of Rock‐Cemented Coal Gangue‐Fly Ash Backfill Bimaterials with Different Coal Gangue Particle Sizes

Properties of rock‐cemented coal gangue‐fly ash backfill (CGFB) bimaterials determine the effects of strip CGFB mining on controlling the surface subsidence in coal mines, which are affected by the coal gangue particle size in CGFB. In this paper, uniaxial compression tests were conducted on the coarse sandstone‐CGFB composite samples with different coal gangue particle sizes, and their strength, acoustic emission (AE), and failure characteristics were investigated. The uniaxial compressive strength (UCS) and elastic modulus of the composite sample decreased with the coal gangue particle size. The strength of the composite sample is mainly dependent on that of CGFB in it, affected by interactions between CGFB and coarse sandstone. The deformation of the coarse sandstone weakened the damage accumulation within CGFB, resulting in the strength of the composite sample larger than that of CGFB. The average UCS values of composite samples with coal gangue particle sizes of 0∼5 mm, 5∼10 mm, and 10∼15 mm, increased by 10.78%, 14.98%, and 12.70% compared with CGFB in them, respectively. AE event signal regularity of the composite sample was divided into three stages: rising period, calm period, and active period. The intensity and frequency of AE event signals in three periods were strengthened with the coal gangue particle size. The calm period can be taken as the precursory information for the failure and instability of composite sample under loading, whose duration became shortly with the coal gangue particle size. The rebound deformation of coarse sandstone caused the fluctuations of AE event signals at the later stage of active period. The failures of the composite sample occurred within CGFB, and no obvious failures were found in the coarse sandstone. The CGFB mainly experienced the splitting failure accompanying by varying degrees of surface spalling failures. The broken degree of CGFB increased with the coal gangue particle size, and the largest weight ratio of CGFB fragments (chips) after failure was determined by the coal gangue particle size.

The Effect of Acid Mine Drainage Corrosion on the Creep Deformation of Cemented Gangue Backfill

Acid mine drainage (AMD) is a hazardous by‐product of coal mining, which may intensify the creep deformation of cemented gangue backfill (CGB) in solid backfill mining. In this study, the long‐term stability and creep property of CGB soaked in AMD were quantitatively measured by experimental and theoretical analysis. The uniaxial compressive strength, elastic modulus, and mass of CGB soaked in AMD, with pH of 5.56 and soaking time of 30 to 360 days, were tested. The change trend of compressive strength, elasticity modulus, and mass first increased, then decreased, and finally ended at 94.37%, 96.68%, and 98.00%, respectively. The respective creep processes of CGB soaked in AMD and untreated CGB were similar, initial creep stage lasted only for a short time, and no creep deformation occurred in the steady creep stage. Moreover, the long‐term strength of CGB soaked in AMD was 98.6% of the untreated CGB. The creep law of the CGB soaked in AMD was accurately fitted by using the Kelvin model. The theoretical analysis revealed that the final creep deformation of the CGB column soaked in AMD was only 4.4 mm. The results of this paper show the possibility of using CGB in AMD‐accumulating goaf.

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

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.