Rock Specimens Research Articles

Rock failure mechanisms based on rheological dynamics

This paper investigates the mechanisms of rock failure related to axial splitting and shear failure due to hoop stresses in cylindrical specimens. The hoop stresses are caused by normal viscous stress. The rheological dynamics theory (RDT) is used, with the mechanical parameters being determined by P- and S-wave velocities. The angle of internal friction is determined by the ratio of Young's modulus and the dynamic modulus, while dynamic viscosity defines cohesion and normal viscous stress. The effect of frequency on cohesion is considered. The initial stress state is defined by the minimum cohesion at the elastic limit when axial splitting can occur. However, as radial cracks grow, the stress state becomes oblique and moves towards the shear plane. The maximum and nonlinear cohesions are defined by the rock parameters under compressive strength when the radial crack depth reaches a critical value. The efficacy and precision of RDT are validated through the presentation of ultrasonic measurements on sandstone and rock specimens sourced from the literature. The results presented in dimensionless diagrams can be utilized in microcrack zones in the absence of lateral pressure in rock masses that have undergone disintegration due to excavation.

On the Initial Fabric of Naturally Occurring and Reconstituted Weakly Cemented Geomaterials

The understanding of naturally occurring materials such as clay, sand, hard and soft rocks under a common theoretical framework has been a topic of persistent research interest. Over the past few decades, various sample reconstitution techniques have been developed in the literature to mimic in situ conditions, and to parse carefully the influence of various components in a cohesive-frictional geomaterial such that their behavior can be folded into the broad ambit of a continuum mechanics framework. The initial fabric of natural rock specimens is compared with reconstituted cemented sand samples using X-ray computed tomography (XRCT) scans. The efficacy of laboratory reconstitution techniques in replicating the initial microstructural features of natural rocks is evaluated here. Additionally, discrete element method (DEM) protocols which are often employed in generating cohesive granular ensembles are employed here and compared against the naturally occurring and artificially reconstituted fabric. A significant difference is observed in the grain boundaries of reconstituted and naturally occurring rocks. Additionally, the arrangement of particles, the orientation of grain contacts, and their coordination number are examined to assess the efficacy of laboratory-reconstituted specimens at micro-length scale.

Failure behaviour of various rocks coated new thin spray-on liner with different curing time under uniaxial compression: Insights from AE and DIC

Thin spray-on liners (TSL) is increasingly popular in underground mine support operations. In this study, a new type of TSL material is proposed, and its macro-micro physical and mechanical properties are characterized. A systematic investigation on the deformability behaviour of six rocks (i.e., coal rock, soft red sandstone, marble, hard sandstone, granite, and limestone) covered TSL materials with different curing ages (i.e., 0-day, 3-day, 7-day, 14-day, 21-day, and 28-day) under uniaxial compression circumstance is performed using acoustic emission (AE) and digital image correlation (DIC) methods. The results show that TSL improves the peak strain of each rock sample, except hard sandstone. The impact of TSL on the peak compressive strength of coal rock, soft red sandstone, and marble is nearly negligible, while it diminishes the strength of hard sandstone, granite, and limestone. As the TSL ages, the peak strength and elastic modulus of limestone initially increase and then decrease, reaching the minimum at 14-day of age, with values 89.81 MPa and 23.13 GPa respectively. However, for other rock samples, the effect of TSL age is not significant. The AE signal produced inside the rock diminishes during the elastic-plastic stage, while the ratio of shear cracks increases upon failure of each rock specimen. The macroscopic failure modes of coal rock and limestone exhibit prominent axial splitting characteristics, whereas marble and hard sandstone undergo mixed failure processes involving shear, tension, and shear-tension. The test data highly correspond to the macroscopic fracture characteristics. The research findings can serve as guidance for TSL support in both soft and hard rock scenarios.

Analysis of failure properties of red sandstone with structural plane subjected to true triaxial stress paths

In order to study the mechanical behavior and failure characteristics of rock mass with the structural plane in complex deep stress environment, the QKX-YB200 true triaxial rockburst test system, acoustic emission, and digital video recorder were adopted to conduct true triaxial loading and unloading indoor tests on the red sandstone cube specimens. The results show that: (1) Under true triaxial loading conditions, all specimens propagate in the form of anti-wing crack, and the dip angle of the structural plane is linearly related to the average value of the anti-wing crack propagation angle; under true triaxial unloading conditions, the specimens with structural plane dip angles of 30°, 45°, and 60° propagate in the form of wing crack, while those with a 90° angle propagate anti-wing cracks, and the closure of structural plane is related to the the crack type at the tips of structural plane. (2) The unstable failure stages in the stress–strain curve under true triaxial unloading are longer and exhibit more pronounced fluctuations; the peak strength of the specimens under the conditions of true triaxial loading and unloading decrease first and then increase with the increase of the dip angle, reaching the lowest at 45°. (3) During the true triaxial unloading tests, the rockburst degree of the intact rock specimens is more violent than that of the specimens with a structural plane. Additionally, the dip angle of the structural plane influences the severity of rockbursts under the same stress path. (4) The crack propagation mechanism and the closure degree of structural planes under different true triaxial stress paths and dip angles are discussed. It is observed that the crack initiation mode around the structural plane tips and the crack mode near free surface are closely related to the stress environment in different areas of the specimens. (5) Based on the indoor test results and previous experimental data, the differences in peak strength characteristics between open structural planes and closed structural planes are preliminarily analyzed and compared.

A phase field model with modified volumetric-deviatoric decomposition for the mixed-mode fracture of rock

Recent attempts of phase field models to simulate rock fracture problems have been regarded as fruitful, owing to their powerful crack characterization capability. However, existing phase field models still exhibit limitations in simulating quasi-coplanar shear cracks and related coalescence patterns that often occur in rock failure. In this study, we propose a novel phase field model to simulate the mixed-mode fracture, in which a modified volumetric-deviatoric decomposition that combines the advantages of the volumetric-deviatoric decomposition and the spectral decomposition is conducted to distinguish between tensile, tensile-shear, and compressive-shear fractures; to reduce unrealistic damage in the area outside the crack trajectory, a threshold parameter is introduced into the degradation function to control whether the related energy participates in damage evolution; and the hybrid formulation is employed to efficiently and robustly solve the displacement and phase fields alternately. The feasibility of the proposed phase field model is first validated by a benchmark example. Next, the application of this model to the simulations of different rock specimens under uniaxial compression reveals a better agreement with experimental observations than previous simulation results, demonstrating an advancement over existing phase field models.

Reflectance spectroscopy analysis and lithium content estimation in lithium-rich rocks and stream sediments: Insights from Tuanjie Peak, Western Kunlun, China

Lithium, a rare metal of strategic importance, has garnered heightened global attention. This investigation delves into the laboratory visible-near infrared and short-wavelength infrared reflectance (VNIR-SWIR 350 nm–2500 nm) spectral properties of lithium-rich rocks and stream sediments, aiming to elucidate their quantitative relationship with lithium concentration. This research seeks to pave new avenues and furnish innovative technical solutions for probing sedimentary lithium reserves. Conducted in the Tuanjie Peak region of Western Kunlun, Xinjiang, China, this study analyzed 614 stream sediments and 222 rock specimens. Initial steps included laboratory VNIR-SWIR spectral reflectance measurements and lithium quantification. Following the preprocessing of spectral data via Savitzky-Golay (SG) smoothing and continuum removal (CR), the absorption positions (Pos2210nm, Pos1910nm) and depths (Depth2210, Depth1910) in the rock spectra, as well as the Illite Spectral Maturity (ISM) of the rock samples, were extracted. Employing both the Successive Projections Algorithm (SPA) and genetic algorithm (GA), wavelengths indicative of lithium content were identified. Integrating the lithium-sensitive wavelengths identified by these feature selection methods, A quantitative predictive regression model for lithium content in rock and stream sediments was developed using partial least squares regression (PLSR), support vector regression (SVR), and convolutional neural network (CNN). Spectral analysis indicated that lithium is predominantly found in montmorillonite and illite, with its content positively correlating with the spectral maturity of illite and closely related to Al-OH absorption depth (Depth2210) and clay content. The SPA algorithm was more effective than GA in extracting lithium-sensitive bands. The optimal regression model for quantitative prediction of lithium content in rock samples was SG-SPA-CNN, with a correlation coefficient prediction (Rp) of 0.924 and root-mean-square error prediction (RMSEP) of 0.112. The optimal model for the prediction of lithium content in stream sediment was SG-SPA-CNN, with an Rp and RMSEP of 0.881 and 0.296, respectively. The higher prediction accuracy for lithium content in rocks compared to sediments indicates that rocks are a more suitable medium for predicting lithium content. Compared to the PLSR and SVR models, the CNN model performs better in both sample types. Despite the limitations, this study highlights the effectiveness of hyperspectral technology in exploring the potential of clay-type lithium resources in the Tuanjie Peak area, offering new perspectives and approaches for further exploration.

A B-spline material point method for deformation failure mechanism of soft–hard interbedded rock

Geological hazards related to soft–hard interbedded rock are frequent in rock engineering. The material point method (MPM) is a mesh-free numerical approach specifically designed for analyzing large deformations. Notably, significant grid-crossing errors frequently arise when material points traverse the underlying grid. To investigate the failure mechanism of soft–hard interbedded rock, an enhanced MPM incorporating B-spline basis functions and Voronoi polygon discretization is developed and subsequently validated through comparisons with uniaxial compression test data and other numerical methods. The numerical results of soft–hard interbedded rock specimens associated with different soft layer dips (SLD) and confining pressures indicate that the SLD has a great effect on compressive strength and crack extension at low confining pressure. Rocks from SLD-30° to SLD-75° correspond to the “sliding failure along discontinuities” failure mode and have lower compressive strength than rocks with other SLD angles. It is also demonstrated that the propagation of cracks leads to a significant alteration in the internal stress state of the rock, and that stress concentrations at the crack tip exacerbate the development of failure surface. Furthermore, the failure mode of soft–hard interbedded rock can be categorized into four types: (1) sliding failure across multiple discontinuities, (2) tensile fracture across multiple discontinuities, (3) sliding failure along discontinuities, (4) tensile-split along discontinuities.

Mapping distribution of fractures and minerals in rock samples using Res-VGG-UNet and threshold segmentation methods

Understanding the internal structures of rock and their subsequent evolution is essential across multiple disciplines. Fractures and mineral grains are significant components of internal structures. These components influence natural processes and human activities, such as oil migration and extraction. With advancements in non-destructive evaluation (NDE) techniques, especially X-ray computed tomography (CT), in-depth analyses of internal structures of rock have become feasible. However, the data-intensive nature of CT scans necessitates more efficient post-processing algorithms. This research uses the Residual Network-Visual Geometry Group-UNet (Res-VGG-UNet) deep learning framework in conjunction with two threshold segmentation methods to capture components like fractures, the drilled hole, and minerals. The performance of Res-VGG-UNet is evaluated against DeepLabv3+ and Weka3D. Key findings include the capability of the deep learning technique to distinguish between various components and the performance of single-slice-based versus multi-slice-based threshold segmentation methods. VGG16 and VGG19 outperform DeepLabv3+ and Weka3D in the performance of fracture classification. Moreover, a 3D reconstruction technique is introduced, providing enhanced insights into internal features of the rock. We conclude this paper by showing the potential to use the outcomes of the deep learning and multi-slice-based threshold segmentation methods to develop discrete element models, accurately reflecting the physical characteristics of rock specimens.

Influence of ice properties on wave propagation characteristics in partially frozen soils and rocks: A temperature-dependent rock-physics model

A better understanding of the temperature effects on the propagation characteristics of elastic waves in frozen soils and rocks is imperative for accurately quantifying their freezing degrees. Although the existing rock-physics models based on the three-phase Biot (TPB) theory adeptly interpret observed velocity variation with temperature (VVT) curves, they often lack a comprehensive understanding of the mechanisms underlying attenuation variation with temperature (AVT) curves. In this study, we first extend the TPB theory to incorporate the temperature-dependent properties of ice, such as changes in volumetric fraction, morphology, and viscoelasticity, by integrating the relevant thermodynamic laws. Model parameters related to ice properties and interactions, such as rigidity, shear moduli, density, and friction, are redefined. Then, using a numerical rock-physics modeling approach, we examine influential factors and modes of the wave VVT and AVT responses. Our results indicate that the P- and S-wave velocities increase with source frequency, consolidation degree, and frame-supporting ice content, whereas they decrease with temperature and pore-floating ice content. The P- and S-wave attenuation factors increase with the frame-supporting ice content and decrease with the consolidation degree. Rising temperatures tend to amplify the peak magnitude of the P-wave attenuation factors and shift the central frequency of the S-wave attenuation factors. Finally, within a temperature-controlled laboratory environment, we conduct ultrasonic wave transmission testing on brine-saturated sediment and rock specimens. The results demonstrate that as the temperature increases from −15°C to −3°C, the P- and S-wave velocities decrease, whereas the P-wave attenuation factors decrease and the S-wave attenuation factors initially rise before declining. Our viscoelastic TPB theory outperforms the existing ones in interpreting the S-wave AVT observations. This temperature-dependent rock-physics model holds promise for interpreting the sonic logging data in the time-lapse monitoring of permafrost, glaciers, and Antarctica.

An improvement in the method of correcting indirect radial strain measurements during triaxial strength tests in rocks

The present article provides an improvement in the method to correct indirect strain measurements in triaxial compressive strength tests through axial displacement and hydraulic fluid volume change measurements. The improvement focused on reducing the parameters of the formula proposed for indirect volumetric strain in the original method, thereby facilitating the development of a simpler formula in which the radial strain depends on only two parameters: the initial volume of the rock specimen and the volume changes of the hydraulic fluid for each instant. The comparison between the improvement proposed, and original method resulted in a mean absolute difference of 0.003.•This improvement does not depend on the axial strain, unlike the original method, which requires correcting the indirect axial strain measurements before correcting the indirect radial strain measurements.•This improvement can be useful for research on the stress-strain behavior of intact rock under laboratory conditions, such as in the study of the post-peak state.

Analysis of shear fracture characteristics and energy evolution of salt rock under real-time coupled thermo-mechanical conditions

Studying the shear fracture behavior of salt rock is of great importance for the identification of precursor information for geological disasters such as underground salt cavern caprock slippage, fault instability displacement, and zonal destruction of the surrounding rock. Despite its undeniable importance, research on the shear fracture characteristics of salt rock under real-time high-temperature and high-pressure triaxial conditions remains scarce. To address this research gap, this study employed a self-developed rock real-time high-temperature and high-pressure multi-field coupled triaxial universal testing machine to perform triaxial shear fracture tests on salt rock punch through shear (PTS) specimens across a wide range of confining pressures (0 to 25 MPa) and real-time temperatures (20 °C to 600 °C). Additionally, the internal pore fracture structures of the salt rock after different coupled thermo-mechanical (TM) treatments were examined using micro-computed tomography (MCT) and metallographic microscopy. The results reveal the complexity of fracture behavior in salt rock. At normal temperature and pressure, salt rock specimens primarily fractured into short rods and hollow cylindrical forms, with wing cracks appearing on the surfaces of the cylinders. Under high-temperature and high-pressure conditions, the salt rock exhibited more intense shear slippage phenomena, although the specimens did not undergo complete fracturing. Notably, the internal pore fractures in the salt rock under real-time coupled high-temperature and high-pressure displayed a competitive interaction between self-healing and thermal damage, leading to a significant nonlinear increase in mode II fracture toughness with temperature. Through the analysis of energy absorption and dissipation, this study further elucidates the shear fracture mechanism of salt rock under coupled TM conditions. Overall, the findings of this paper not only deepen our understanding of the mechanical behavior of salt rock under high-temperature and high-pressure conditions but also provide crucial theoretical support for the design and risk management of underground salt cavern projects.

Fast permeability measurement for tight reservoir cores using only initial data of the one chamber pressure pulse decay test

In this study, a mathematical model for fast determination of the permeabilities of tight rocks using measurements taken from the initial period of the One Chamber Pressure Pulse Decay (OC-PPD) test is presented. The model applies to measurements taken both before and after the pressure pulse front has reached the downstream end of the specimen. The analytical solutions for the pressure decay in the upstream chamber are derived based on a parabolic arc approximation of pore pressure distribution along the test specimen. This approximation allows converting the initial–boundary value problem of fluid diffusion in the specimen, governed by partial differential equations, to a system of ordinary differential equations that can be easily solved by explicit formulae. Thus, an explicit formula for the pressure decay rate is obtained, which enables inverse analysis of the initial experimental data to estimate the rock permeability. The proposed method expedites the pulse decay test as it does not require the system to reach equilibrium. The method is validated with three sets of experimental data of the OC-PPD test using helium as the diffusing fluid, for which the relative error of the permeability is found to be less than 6%. This method is particularly useful if the equilibrium time of the pulse decay test for rock specimens with permeabilities in the range of nano-Darcy takes hours or days.

Mechanical behavior and energy characteristics of red sandstone with different seawater immersion heights under biaxial compression

Rock structures engineered during undersea mining are typically subjected to varying water distributions due to the motion of seawater, which considerably influences their stability. Hence, it is essential to understand the influence of seawater distribution on the mechanical behavior and energy characteristics of rocks. In this study, biaxial compression tests were conducted on red sandstone at various seawater immersion heights, and acoustic emission signals during compression were monitored. The results illustrate that the mechanical properties of the red sandstone deteriorate significantly upon seawater immersion. With an increase in seawater immersion height, the peak strength and elastic modulus of the rock specimens decreased exponentially. When the seawater immersion height was varied from 0 to 1/4 H under lateral stresses of 5, 10, 15, and 20 MPa, the peak strength decreased by 18.94%, 20.29%, 17.47%, and 14.87%, respectively, and the elastic modulus decreased by 4.6%, 8.1%, 11.7%, and 10.9%, respectively. Brittleness also decreased gradually. During compression, the acoustic emission (AE) and accumulated AE counts exhibited a stationary phenomenon, first increasing slowly and then suddenly. However, the AE counts decrease with increasing seawater immersion height. Meanwhile, with increasing seawater immersion height, the proportion of tensile cracks gradually increased and that of shear cracks gradually decreased. As the seawater immersion height increased, both the peak total input strain energy and peak total elastic strain energy decreased, whereas the peak total dissipated strain energy exhibited the opposite trend.

Modern Geochemical and Tectonic Exploration—The Key Factor in Discovering the Northern Copper Belt, Poland

The discovery of the Northern Copper Belt in SW Poland is a result of an extensive exploration project with a key role played by various science-related methods. The project relied on mapping the distribution of mineral zones in the entire Fore-Sudetic Monocline, a unit known for its occurrences of Cu-Ag orebodies. This approach involved the examination of historical drill cores from over 400 oil and gas holes in this area, with the collection of samples for laboratory analyses. A close relationship was confirmed between the distribution of orebodies and the transformation of organic matter. Rock-Eval pyrolysis was also performed on selected samples. The tests of rock specimens were accompanied by the reprocessing of historical gravimetric and seismic surveying results. Field magnetotelluric surveying was also performed in certain areas. This phase resulted in the identification of areas with a high probability of finding the best ore, allowing for the initiation of the drilling stage. So far, 37 exploratory boreholes have been drilled in those locations, nearly all of them with highly positive results. The Northern Copper Belt consists of three deposits, Nowa Sól, Mozów, and Sulmierzyce North, along with numerous prognostic areas distributed therebetween. The future production of copper, silver, and the accompanying valuable elements presents a chance to provide the whole of Europe with a new plentiful supply of those critical raw materials.

Anisotropic behavior and mechanical characteristics of the Montney Formation

This study investigates the rock mechanics and anisotropic properties of the Montney Formation, Alberta, through two sets of experiments: unconfined compressive strength tests and triaxial compression tests, supplemented by ultrasonic wave velocity measurements. These tests enabled the calculation of dynamic and static stiffness properties and Thomsen anisotropy parameters (ε, δ, γ). Our findings reveal that the Montney Formation exhibits weak anisotropy, with ε values generally below 0.10, contrasting with other strongly anisotropic shale formations. Specimens exhibiting higher clay content and total organic carbon levels show more pronounced anisotropy. Static measurements exhibit a higher degree of anisotropy compared to dynamic measurements. The investigation also explored loading and unloading stiffness parameters, noting a higher E loading-to-unloading ratio for rock specimens with lower elastic properties. This provides important information on the rock's response to stress path effects during stimulation and exploitation. The study also discusses other rock mechanics parameters including Poisson's ratio, tensile strength, and brittleness. The research contributes to a more comprehensive understanding of the geomechanical and petrophysical behavior of the Montney Formation, aiding reservoir characterization and hydrocarbon exploration and production.

Prediction of Mode-I Fracture Toughness of the ISRM-Suggested Semi-Circular Bend Rock Specimen Using ANN and Optimized ANN Models

Prediction of Mode-I Fracture Toughness of the ISRM-Suggested Semi-Circular Bend Rock Specimen Using ANN and Optimized ANN Models

Accuracy and Precision of the Geopyörä Breakage Test

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the Geopyörä. Force measurement was assessed just for its precision. The outputs were compared directly to the drop weight test (DWT) measures of fragmentation at the same energy and fitted A and b parameters. Test reproducibility was evaluated using a Round-Robin methodology, testing several samples in multiple laboratories. The results confirmed that the new test has sufficient accuracy to match DWT results and excellent precision to assure reproducibility.

Simulation of cracking processes of the rectangular cavern surrounding rock based on a continuum–discontinuum method

In a self-developed continuum–discontinuum method that considers the internal cracking of quadrilateral elements, the computational domain is divided into quadrilateral elements with high accuracy. After cracking, the cracks propagate along the boundaries of the elements and the diagonal lines of the quadrilateral elements. Deformation, cracking, and contact of rocks can be simulated using this method. For Brazilian disc rock specimens, the rapid increase of tensile crack segments corresponds to a rapid decrease of the load. Compared with the original method, crack propagation is smoother in the improved method. This is because the propagation paths of cracks are fewer in the original method, and the propagation of cracks is hindered. For uniaxial compressive rock specimens, when two shear cracks intersect, one crack may dominate, forming a main crack, and its direction is consistent with the theoretical direction obtained using the Mohr − Coulomb criterion. For the cavern surrounding rock models, some long and narrow shear cracks appear in the surrounding rock, and their shapes are like logarithmic spirals. An interval exists between the shear cracks, and the more to the interior of the surrounding rock, the larger the interval between cracks. The higher the hydrostatic pressure, the faster the shear crack propagates and the easier it is to form a shear slip line. With an increase of cavern size, the depth and range of the shear cracks increase. With a decrease of the internal friction angle, the interval between the cracks increases, and the propagation direction of the cracks become more internal.

Study on the Influence of Temperature and Water Content on the Static Mechanical Properties of Sandstone.

The area of permafrost worldwide accounts for approximately 20% to 25% of land area. In cold-climate regions of China, which are garnering international attention, the study of low-temperature and moisture effects on rock mass mechanical properties is of significant importance. China has a wide area of cold regions. This research can provide a foundation for China's exploration activities in such extreme environments. This paper examines the mechanical behavior of rock specimens subjected to various low temperatures and water contents through uniaxial compression tests. The analysis encompasses failure modes, stress-strain relationships, uniaxial compressive strength (UCS), and elastic modulus (EM) of these specimens. Findings reveal that at lower temperatures, the rock specimens' fracture patterns transition from compressive shear failure to cleavage failure, reflecting a shift from a plastic-elastic-plastic to a plastic-elastic response. Specifically, saturated rocks exhibit a 40.8% decrease in UCS and an 11.4% reduction in EM compared to their dry counterparts. Additionally, in cold conditions, an increased water content in rocks primarily leads to vertical cracking. Under such conditions, saturated rocks show a 52.3% decline in UCS and a 15.2% reduction in EM, relative to their dry state.

Macroscopic experimental study and microscopic phenomenon analysis of damage self-healing in salt rock

Salt rock is characterized by a low porosity, low permeability and self-healing ability, and it is one of the most common materials used for underground energy storage and construction in underground nuclear waste repositories. Studying the healing of macroscopic cracks in salt rock under different conditions is important for ensuring the stability of the rock surrounding a salt cavern. To evaluate the healing ability and effect of cracks in salt rock at the macroscale, two tests were designed to directly assess the healing ability of salt rock by analyzing the tensile strength and permeability recovery of healed crack surface. Furthermore, the microstructure of the healed macroscopic fractures in salt rock was observed using scanning electron microscopy (SEM), and the microscopic mechanisms of salt rock damage healing were analyzed. (1) The results show that the presence of water is an important condition for the healing of cracks in salt rocks. Fully fractured salt rock cracks can heal at a low pressure of 160 kPa, and the uniaxial tensile strength of the healed specimens can reach a maximum of 121.1 kPa. It was found via computed tomography (CT) that a healed crack was still a weak surface in the whole specimen. (2) Increases in temperature, environmental humidity, and normal stress all promote the self-healing of salt rock fractures. Based on the experimental data, a model describing the evolution of salt rock damage healing variables with respect to temperature, humidity, and stress was established. It was also observed that the change in salt rock damage healing variables over time during the healing process can be represented by a first-order exponential decay function. (3) Using SEM, detailed micro healing experiments were conducted on NaCl single crystal and impurity-containing salt rock specimens. The healing characteristics of intracrystalline cracks and intercrystalline cracks were studied. It was observed that salt rock damage healing manifests at the microscopic level as the filling of microcracks and crack segmentation caused by grain growth. Additionally, the presence of a certain amount of impurities was found to promote the growth of internal structures that heal cracks within salt rock. These findings are of great significance for evaluating the stability and tightness of the surrounding rock of salt cavern reservoirs.