The role of bedding angle on the mechanic properties and failure modes of shale under cyclic loading and unloading conditions is unclear. This study conducted uniaxial cyclic loading and unloading tests on shales from the Longmaxi Formation with different bedding angles (θ = 0°, 22.5°, 45°, 67.5° and 90°), and characterized their damage evolution through both AE and charge signals. Results show that

The shear strength of rock joints under dynamic normal load (DNL) conditions is quite different from that under constant normal loading (CNL) conditions. However, existing studies seldom involve the shear strength prediction of rock joints under DNL conditions. Therefore, a series of shear tests for rock joints under DNL conditions were carried out. The evolutions of the shear strength parameters,

In domal and bedded rock salt geothermal reservoirs, geochemical dissolution of the in-situ rock salt formation can alter fluid transport properties, thus impacting fluid flow. Coupled Hydro-mechanical–chemical (HMC) modeling is a useful tool to evaluate fluid transport through rock salt geothermal systems and to assess their economic potential. Existing continuum-based numerical simulation of fluid

In deep underground engineering, true triaxial compressive stress and internal microcrack characteristics significantly influence the brittle-ductile transition and anisotropic mechanical behavior of rock, thereby affecting the engineering life cycle. However, current research on the micro-macro mechanical model under true triaxial compressive stress, particularly regarding the rock's brittle-ductile

The presence of complex geometric morphology of single rough-walled rock fractures and the occurrence of nonlinear flow complicate the fracture flow process. Even though the nonlinear flow behaviour in single rock fractures has been studied for decades, existing models are still limited in adequately evaluating nonlinear flow behaviour during shearing. In this study, a series of coupled shear-flow

We present new true triaxial compression data obtained in the ductile regime on Bleurswiller sandstone. The deformed samples show a range of failure modes qualitatively similar to what was reported by earlier experimental studies performed in conventional conditions (axisymmetric compression). In particular, visual inspection and X-ray Computed Tomography imaging reveal compaction localization in all

Existing numerical models cannot well reproduce the fracturing process and reveal the underlying mechanisms of rocks under microwave irradiation. In this work, the electromagnetic-thermal-mechanical multiphysics is decoupled into microwave-induced heating (continuum-based) and thermally-driven fracturing (discontinuum-based), with temperature serving as the key interlink. The rigid-body spring-subset

A comprehensive in situ stress estimation is carried out in the fractured reservoir at the enhanced geothermal system development site in Pohang, South Korea. Various types of stress indicators were collected from the hydraulic stimulation data, drilling records, lost circulation records, well logs, seismic events, and the stress constraints from previously proposed stress models. The comprehensive

The impact of water content on the strength of sedimentary rocks is a critical area of research, particularly in the contexts of disaster prevention and the construction of underground structures. Despite numerous factors being identified as contributors to the strength variations in sedimentary rocks caused by water content, a comprehensive understanding remains elusive. Moreover, only a limited number

Prestress significantly influences the mechanical properties of fractured rocks due to stress-induced anisotropy in the surrounding matrix and the stress-induced closure of cracks. Understanding the stress-dependent elastic moduli and anisotropic properties is crucial for various geoscience applications. The theory of acoustoelasticity only accounts for weak nonlinear elasticity with finite strains

Exploring cracking behavior from mineral-scale do good help to understand the failure mechanism of rock materials. The present study proposes a realistic three-dimensional grain-based modeling (3D-GBM) method considering the actual distribution, geometry and mesoscopic mechanical properties of different minerals in granite samples. The geometrical characteristic and distribution were captured based

Due to the existence of bedding planes in shale oil reservoirs, the complexity of crack networks created by conventional hydraulic fracturing (HF) technology is limited, resulting in low oil production. In this paper, a fatigue loading method was proposed to increase the complexity of the cracking network. The propagation behaviors of small cracks were investigated and compared under both monotonic

Accurate assessment of mechanical behaviour of rock is essential for safe and efficient design of structures on or within rock mass particularly under harsh in-situ stress conditions. Insights from rock engineering practices have revealed that rockbursts can occur at various scales and at any time during mining activities. These violent failure phenomena can be triggered by quasi-static stress redistribution

Constructing pumped-storage power stations using underground reservoirs in mines offers a promising method for large-scale energy storage. Watertight coal pillars have the potential to destabilize under the mine-shock cyclic dynamic loading and the drying–wetting cycles (DWCs). Understanding the fatigue damage mechanism and failure precursors in watertight coal pillars under cyclic dynamic loading

The failure mechanisms of engineering rock masses primarily involve tensile and shear failure. Differentiating between the acoustic emission (AE) signals generated during the tensile and shear damage processes in rock can provide a scientific basis for the classification of acoustic signals in field rock fracture monitoring. This paper presents a study on acoustic emission monitoring during the direct

Rockfalls are critical landslide phenomena affecting human activities, with risk assessment based on hazard evaluation and potential impacts on exposed elements. Traditional methods for estimating unstable rock block volumes require direct measures often in hard-to-reach areas, hazardous, with time consuming approaches. This study introduces a semi-automatic method for estimating the most probable

Ring test for indirect tensile strength measurements utilizes disc specimens with a hole at the center of the disc. Such specimens are found to limit the stresses at the specimen-platen contact and transfer the tensile stress to the upper- and lower-hole boundaries in ring specimens. Researchers observed that the tensile strength of a ring specimen tends to decrease as the ratio of the hole-radius

In the present paper the problems of the nonlinear debonding of anchorage interface, the strain-hardening and rupture of rockbolt, and the progressive damage of heterogeneous rock for the fully grouted rockbolt under axial loads are studied. A micromechanical numerical model is developed and implemented into the finite difference programme, to analyze the load transfer mechanism and damage evolution

In this paper, the problem of transporting rock material deep into the working is addressed. In the case of coal, literature reports indicate that sorbed gas is responsible for coal mass transport. As a result of laboratory tests, the marginality of sorption phenomena occurring in dolomite was confirmed. Transport of rock material during rock and gas outburst takes place in several stages. In the first

Permeability is a critical parameter in coalbed methane (CBM) recovery and received increasing attention in recent years. The slip effect and effective stress exert competing influences on permeability, with coal exhibiting varying sensitivities to effective stress depending on their pore structures. The presence of water further complicates these interactions, affecting both the slip effect and permeability

The degradation of mechanical characteristics of sandstone, a common engineering material in acid environment, is directly related to the project service life forecast. In order to investigate the influence of water–rock interaction on the mechanical properties of red sandstone, a series of uniaxial and triaxial compression tests were conducted on sandstone immersed in solutions of different pH values

Garnet and steel shot have advantages and disadvantages in terms of cutting performance and economic efficiency as single abrasive materials for cutting rock and concrete using abrasive waterjet. However, the application of abrasive waterjet technology in construction sites is still limited due to the cutting performance and cost limitations of single abrasive. A new strategy is needed for effective

Understanding the fracture behavior of rock after thermal treatment is important in the deep rock engineering, such as nuclear waste disposal and geothermal energy exploration. In this work, to investigate fracture properties of thermally treated rock under compression-shear loading, a series of variable angle shear (VAS) tests were performed on shear-box (SB) granite specimens exposed to temperatures

Coal bursts, arising from abrupt dynamic disturbances from mining tremors, are among the most critical dynamic disasters in underground coal mines. Understanding the dynamic disturbance process of mining tremors is crucial for unravelling the mechanism behind coal bursts and identifying high-risk zones. However, previous studies have often utilized oversimplified source representations to model the

Multistage fractures in different reservoirs exhibit competitive extension and mutual feeding mechanisms under different fracturing sequence conditions. To better understand these mechanisms for a more efficient extraction of mine gases, a combination of true triaxial physical tests and numerical simulation was performed in this study. The expansion process of hydraulic fractures in different layers

In this study, dynamic photomechanical blasting experiments were conducted to investigate the interaction mechanisms of dual cracks induced by explosions at different relative positions. The experimental results demonstrate that both cracks penetrate when the actual relative vertical distance at which the crack tips begin to interact is within 10 mm in the experimental group; however, when it exceeds

A prototype finite element double porous Thermo-Hydro-Mechanical (THM) model that considers elastoplastic and damage evolution effects, is used to investigate deformability, fluid flow and heat transfer during injection of carbon dioxide (CO2) injection. The primary objective is to explore the feasibility of injecting CO2 at temperatures lower than the surrounding formation, including subzero conditions

Fluid extraction from sandstone oil, gas, or geothermal reservoirs causes elastic and inelastic compaction of the reservoir, which may lead to surface subsidence and induced seismicity, as observed in the Groningen Gas Field, Netherlands. The inelastic compaction is partly caused by rate- or time-dependent processes, meaning that compaction may continue even if production is stopped. To reliably evaluate

The geometric shape of the slope and the distribution characteristics of the complex fracture system significantly impact the stability of highly-jointed rock slopes. Constructing an accurate three-dimensional (3D) geological model is crucial for the 3D stability analysis of these slopes. However, the numerous minor discontinuities in rock slopes complicate model construction and reduce computational

Underground infrastructures are crucial for resource extraction, energy storage, and space utilisation. The geomaterials that make up these structures, such as rock and concrete, are subjected to multiaxial stress conditions and are frequently exposed to dynamic and extreme loadings caused by both natural disasters and human activities. These stresses are particularly significant during the construction

Microwave fracturing has great potential in improving the efficiency of hard rock breaking. However, the pore evolution, which can be regarded as the damage accumulation and progressive failure of the rock subjected to microwave irradiation, remains unclear. In this study, nuclear magnetic resonance (NMR) is employed to investigate the pore evolution and fracture mechanism of the sandstone under different

Rock fragmentation is a critical process for mineral extraction and for mitigating overstressed rock in geotechnical applications. In this study, 3D-printed concrete was used to simulate the stratified rock mass, and experimental and numerical methods were employed to investigate crack propagation under static expansive loadings in transversely isotropic rocks. Two types of cracks were observed in

This study performed mechanical tests and monitored acoustic emissions (AE) in shale samples with six bedding layer orientations (β = 0°, 30°, 60°, 90°, 120°, and 150°) to investigate the progressive damage mechanisms under direct shear. The results revealed that the peak shear load (Pcr), crack initiation threshold (Pci), crack damage threshold (Pcd), and cumulative AE count exhibited an approximate

Stress-induced brittle fracturing near an excavation boundary results in a volume increase, known as bulking. Excessive bulking places added demand on the rock support, which, if not detected and addressed through preventative support maintenance (i.e., proactively added reinforcement), can cause the support to fail, leading to a safety hazard and costly production delays for underground mining operations

Underground hydrogen energy storage (UHES) in lined rock caverns (LRCs) represents a crucial solution to the challenge of unstable and uneven clean energy generation. Nevertheless, the attainment of enhanced storage efficiencies frequently necessitates the utilization of elevated hydrogen storage pressures. Consequently, a comprehensive understanding of the elastic-plastic mechanical response of surrounding

Fluid injection via a vertical well into a high-temperature formation may induce multiple longitudinal thermal fractures, which may eventually transition to two-wing fractures during fracture propagation, depending on horizontal stress ratio κ. In this study, we develop a plane strain model with radial heat conduction to investigate either two-wing fractures under highly anisotropic stresses κha≫1

Understanding fault dynamics is essential for comprehending the underlying mechanisms of seismic events. This study introduces a novel fault activation-shearing-sliding model within a peridynamic (PD) framework, characterized by distinctly defined static and kinetic frictional behaviors. Static friction bonds are developed to sustain normal forces perpendicular to the fault plane and to manage tangential

Understanding fracture slip susceptibility in geothermal reservoirs is central to the control of fluid injection-induced seismicity. To investigate the role of regional fracture systems on induced seismicity, a coupled thermo-hydro-mechanical (THM) model containing fracture networks was developed, which features direct coupling between different physics for explicit fractures, fractured rocks (porous

In-situ stress is essential in shale reservoir fracturing, driving oil and gas migration and informing wellbore stability and drilling optimization. The accurate prediction of 3D in-situ stress is inseparable from seismic data. However, existing methods predominantly rely on empirical formulas or simplified assumptions, which limit their accuracy in representing the real distribution of in-situ stress

Chemical and mechanical processes are coupled in many geological and geochemical environments. Reactive processes anneal defects and restructure grain boundaries, modifying their elastic properties, levels of internal friction, wave propagation rates and fracture behaviors. The nature of these changes is, however, contingent on the initial state of the rock. In this study, impulse excitation was used

Multiwell fracturing is a key technology for developing shale gas and shale oil reservoirs. In this study, a multiple planar 3D (PL3D) fracture simulator that can capture multiple thin layers was developed to examine the propagation of multiple fractures during multicluster fracturing in multiple horizontal wells. The simulator considers multiple thin layers in the vertical direction. The results of

Impregnated diamond bits (IDBs) are widely used for drilling in hard formations. To improve the drilling efficiency and exposure behavior of IDBs in granite, three types of Cu-based basalt fiber (BF) composite IDBs were designed and prepared by using the medium-frequency induction hot-pressing and sintering method, in which 0 wt% BF and 25 vol% diamond were used in 0BF25D IDB, 1 wt% BF and 25 vol%

This research develops an energy-driven constitutive model designed to tackle the complex phenomenon of grain crushing in porous rocks. Initially, a novel coupled relationship is proposed to integrate various energy dissipation mechanisms, including both plastic and crushing effects, using spherical polar coordinates. This approach results in a robust coupling of energy dissipation, providing a comprehensive

The stress-strain state of the saturated porous media determines the behavior of fracturing, which defines the efficiency of developing tight oil, shale, coalbed, and thermal energy fields. Therefore, reliable hydromechanical coupled simulations with destruction reconstruction are critical.

Accurate determination of the representative elementary volume (REV) size plays a pivotal role in analysing the mechanical properties and failure processes of heterogeneous rocks in complex engineering environments. In this study, a novel microstructure modelling strategy (NMMS) for determining the REV size is proposed by combining deep learning and an improved phase-field method (PFM). Micro- and

The long-term stability of jointed rock masses is usually dominated by fault activation, which may be triggered by the dynamic disturbance generated by blasting during mining activities, leading to the occurrence of disasters such as landslides in open-pit and rockbursts in deep mining. The initial stress and dynamic disturbance are key factors that strongly affect the shear creep behavior of rock

The precise forecasting of the weathering degree of surrounding rock holds paramount importance for the scientific design and secure execution of tunnel engineering. The apparent features of the surrounding rock serve as critical indicators for evaluating its weathering degree. This paper endeavors to quantify the rock apparent features based on an improved Computer vision model and establish a multi-source

Fluid flow in subsurface tight reservoirs containing pores, microcracks and macrocracks is notably influenced by the characteristics of macro/micro-cracks. A novel hybrid multiscale model is proposed to address the response of macrocracks and pores/microcracks in different spatial scales. Specifically, an equivalent macroscopic model (EMM) deduced from locally periodic representative element volume

Hard roof is the primary concern of strata control in underground mining. Various techniques have been utilized to fracture the hard roof and control the failure of strata. Understanding the impact of cracks on strata behaviour is vital for optimizing strata control strategies. In this study, the hard roof was regarded as a beam structure with different loading, support, and boundary conditions. The

Elastic (seismic) wave stimulation is considered one of the unconventional enhanced oil recovery (EOR) methods. Increasing water quantity in the high permeability layer of a mature oil reservoir is highly challenging and can significantly decrease the ultimate recovery due to the reservoir heterogeneity. Using seismic waves can be considered low-cost, environmentally friendly, and illuminates the entire

Pressure, temperature, and infilling fluids influence the petrophysical properties and the associated damaging processes of rocks at all scales and at all depths. Moreover, each fluid-rock system possesses peculiar mechanical behavior, being this particularly complex in carbonate rocks. We focus on an outcropping carbonate-bearing reservoir (Majella, Central Italy), that represents a very good analogue

Quantitative characterization of the geo-mechanical properties of shale and organic matter (OM) holds paramount significance in the assessment of shale gas reserves and the design of hydraulic fracturing. However, the mechanical evolution processes during shale hydrocarbon generation and its influencing factors have received limited attention. This study examines the changes in shale mechanical properties

The deformation modulus of rock mass is an essential parameter for evaluating the bearing capacity and deformations. A deformation modulus obtained through conventional approaches, including empirical equations and in situ tests, cannot present the deformation modulus at representative elementary volume (DREV) due to limited test coverage and technical difficulties in harsh geological or topographic

The shear resistance of multi-joint rock masses significantly affects the stability of underground engineering structures. In this work, using 3D printing technology, rock-like samples containing two joints with varying joint spacings and roughness values are prepared and subjected to direct shear tests under different normal stress conditions. The results demonstrate that the shear stress-shear displacement

Percussion rock drills have been widely used in mine development and civil engineering. During percussive rock drilling, a hammer in the rock drill collides with a shank rod several thousand times per minute, and elastic waves generated by the collisions propagate in the shank rod, rods, and a bit. Cemented carbide buttons, which are embedded in the bit, are penetrated into rock by the elastic waves

Mechanical mining and excavation in deep metal mines can be regarded as the process of crushing hard rock by conical pick indentation. In this study, a confining pressure loading device was designed and used to carry out dynamic conical pick indentation crushing tests under confining pressure conditions on three types of granite with varying strengths, using the Split Hopkinson Pressure Bar (SHPB)

The nanoscale elastic moduli and hardness of the constituent minerals of the Class II Kuru granite and the Class I Fauske marble were experimentally investigated. The aims were to correlate the microcrack patterns with the nanomechanical properties of the minerals, and to help understand the important roles of the nanomechanical properties of the minerals in brittle and ductile behaviors. Cylindrical

The storage of renewable hydrogen in salt caverns requires fast injection and production rates to cope with the imbalance between energy production and consumption. This raises concerns about the mechanical stability of salt caverns under such operational conditions. The use of appropriate constitutive models for salt mechanics is an important step in investigating this issue, therefore many constitutive

Understanding the control mechanism of fault rock particle size in fluid-induced fault slip and rupture processes is crucial for mitigating the seismic risks associated with large-scale fluid injection. Here, we conducted laboratory experiments to present the effects of fault rock particle size on slip behavior, friction, and slip modes under fluid injection. Our results demonstrate that the particle

The water-coupling blasting (WCB) technology has received widespread attention due to its advantages of high efficiency and environmental protection. However, the parameters of WCB in practical engineering are generally determined based on the experience and standards of air-coupling blasting (ACB), leading to poor blasting effects and wastage of explosive energy. The study focuses on comparing the