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

Thermally induced fracture is a common phenomenon for concrete and rock-like materials, which presents a significant challenge to numerical modelling. In this work, a thermo-mechanical model for mixed-mode fracture based on phase-field method is proposed. This approach overcomes the difficulties of modelling the thermally induced cracking process when it comes to complex fracture patterns. To simulate

Investigating the pore size characteristics and mechanical properties of the stone bodies formed by residual grout is crucial for understanding the authentic permeability and load-bearing capacity of grouting materials after being scoured by water flow. In this study, the pore size distribution, porosity, uniaxial compressive strength (UCS), and elastic modulus (E) of stone bodies formed by residual

The creep of rock salt greatly influences the performance and safety of rock salt caverns when they are used as an underground repository for oil, nuclear waste, or other hazardous materials. Creep may cause shearing of casings of oil wells drilled through thick layers of salt rock formation. The crystallographic structure of salt rock grains, in-situ deviatoric stress changes caused by excavation

Acoustic emission (AE) and 4D X-ray computed tomography (4D XCT) were used simultaneously to study crack initiation and propagation in two different types of quartz-rich sandstones during the four-point bending experiments. Statistical analysis of the AE response indicated the failure mechanisms and their dynamics. The characteristic changes observed in the AE response defined the timing of the bending

Geotechnical stability analyses of mine waste rock (WR) piles require the critical friction angle (ϕcr) of the coarse blasted rock. However, due to the presence of oversized rock clasts, shear strength can only be characterized on small samples prepared using grading scaling techniques, such as scalping. Thus, considering a testing device able to handle samples of characteristic size D, the material

The flexural toppling occurring in anti-dip layered slopes exhibits complex mechanical behaviours and poses a serious threat to human engineering practices. In this paper, a novel method for evaluating the stability of flexural toppling is proposed by combining analytical solution and numerical simulation. The anti-dip rock layers in the slope are regarded as inclined slabs, and the deflection equations

It is of great importance to determine peak shear strength (PSS) of rock fractures, and data-driven criteria have showed advances in fitting capability in recent years. However, the generalization ability of existing data-driven criteria is limited by dataset size and fracture roughness characterization, which is negative to predictive power and robustness of models. Here we proposed a novel data-driven

Rock failure under external force is a process of energy conversion between the external environment and the rock system. This study aims to quantify rock damage and predict failure from an energy perspective. Infrared radiation (IR) and acoustic emission (AE) technologies were used to monitor the failure process of red sandstone during uniaxial loading experiments in real time. The energy evolution

Fractures control fluid flow, solute transport, and mechanical deformation in crystalline media. They can be modeled numerically either explicitly or implicitly via an equivalent continuum. The implicit framework implies lower computational cost and complexity. However, upscaling heterogeneous fracture properties for its implicit representation as an equivalent fracture layer remains an open question

Fracability evaluation for unconventional reservoir is critical to the selection of candidate zones for post-frac productivity and plays a key role in fracturing design. Historically, the prevailing models for assessing fracability have been largely relied on brittleness indices. Brittleness indices focus mainly on rock fracture characteristics and offers limited assessment of fracture surface area

In many engineering applications, understanding gas adsorption and its induced swelling in nanoporous materials is crucial. In this study, we propose a novel coarse-grained molecular dynamics (CGMD) model with gas-gas, solid-solid, and gas-solid interactions explicitly controlled to achieve the coupling between gas transport and solid deformation at the microscale. The CGMD model has the capability

Rockburst hazards exhibit different spatiotemporal characteristics in deep tunnel excavation. Failure characteristics and energy evolution process of delayed and instantaneous rockburst of basalt rock were investigated based on single-sided unloading experiments under true triaxial conditions. High-speed photography and acoustic emission (AE) monitoring were used, and computed tomography (CT) scanning

Direct measurement of the real contact area of rock joints under normal loading is crucial for comprehending the subsurface geological processes. However, measuring this phenomenon quantitatively at site-scale or laboratory-scale is challenging. Here, we investigate the evolution mechanism of the real contact area in rock joints by conducting closure tests on artificial and saw-cut sandstone joints

Microseismic source mechanisms in underground mines can provide information about the rock mass response to mining. Conventional approaches to such studies rely upon moment tensor solutions that are susceptible to modeling assumptions and need reliable information about source locations and high-resolution velocity models. We propose the application of unsupervised clustering to group microseismic

Axial studies on cable bolts can be conducted using various scale testing apparatuses. Large scale testing, while providing a powerful platform for testing, is expensive and time consuming. This study presents details of a small scale pull out testing campaign on cable bolts and investigates the results achieved. Six popular types of cable bolts were studied using an anti rotation apparatus while encapsulated

In geotechnical engineering, activities such as landslides, rockfalls, blasting, and excavation often subject jointed rock masses to dynamic shear loads, impacting project stability. With continuous innovation of anchoring support technology, the appearance of energy-absorbing bolts has provided more options for rock support. This study selected fully-grouted bolts and energy-absorbing bolts, considering

The Cerchar test is the most commonly used method for evaluating rock abrasivity and estimating tool wear. The conventional test results are reported based on the measured changes of the wear parts, and little attention is paid to what happens on the rock surface and scratching force. Since the cutting process is the interactive behavior between cutting tools and rock materials, the changes in both

Freeze-thaw cycles are recognized as one of the key triggers for some major landslides in cold regions around the world. Though the effects of freeze-thaw cycles on the rock strength degradation have been studied extensively, little effort has been made to qualitatively evaluate how it contributes to the evolution from a stable rock slope to a large-scale mass movement. In this study, we use a discrete

This paper presents a three-dimensional numerical analysis of multiple fracture growth leading to the development of excavation disturbed zones and spalling around deposition boreholes in a geological disposal facility. The development of fracture patterns is simulated with the Imperial College Geomechanics Toolkit, a finite-element based simulator that can model the simultaneous nucleation, growth

The study of rock creep phenomena is of paramount importance due to its potential to trigger geological disasters, such as landslides. To predict and prevent such disasters, creep constitutive models are widely employed to comprehend the time-dependent deformation of rocks. These models encompass various mechanical parameters that describe the intricate stress-strain behaviors. Nevertheless, significant

Post-peak behaviour is crucial for the estimation of rock mass fracturing in cave mining operations where hard rocks can exhibit class-II or snap-back response when subjected to loading. Despite the rapid development of research into class-II rocks under compression, the corresponding behaviour in tensile tests has rarely been investigated, which is critical considering the complexity of rock mass

Conventional seismic designs are currently inadequate to withstand earthquakes in mountain tunnels, which have historically suffered devastating seismic damage. Seismic buffers made of expanded polystyrene geofoam, which are widely used in aboveground structures, have potential applications in tunnels. However, it is not known what the optimal thickness should be, and the seismic effects on such buffers

Sc-CO2 fracturing would be a potential stimulation method for Hot Dry Rock. A series of Sc-CO2 fracturing experiments were performed on granite under different temperature and stress conditions. Quantitative and qualitative analysis of injection pressure curves and cracks were conducted to explain the Sc-CO2 fracturing mechanism under high temperature and high stress conditions. Under the same stress

In the geo-energy industry, fluid injection induces different slip behaviors of a rock fracture, from aseismic creep to dynamic slip. The transition from aseismic creep to dynamic slip is explained by the ratio of the stiffness of surrounding rock and the critical stiffness of the fracture. However, numerous studies suggest multiple controls affecting the slip behaviors, and their joint influences