Majority of the world's mine production is made by surface mining facilities for various reasons. Use of explosives is the most economical way in loosening of the main rock where hard rock formations exist. The degree of fragmentation affects the subsequent excavation and loading operations as well as indicates the success of the blasting process. Although the most preferred method for the measurement

A large amount of lining cracks, pavement uplift and cable trench overturning occurred during the operation of the Dugongling tunnel, which finally led to the closure of the whole line. The study on the lining cracking mechanism is very important to ensure that the tunnel opens again early. First, the actual cracks of the lining were investigated in the field. According to the geological data, the

Comprehensive knowledge and analysis of in situ rock strength and geo-mechanical characteristics of rocks are crucial in hydrocarbon and mineral exploration stage to maximize wellbore performance, maintain wellbore stability, and optimize hydraulic fracturing process. Due to the high cost of laboratory-based measurements of rock mechanics properties, the log-based prediction is a viable option. Nowadays

The chief characteristic of the caving mining method is that caved ores, surrounded by overlying rocks, are drawn from the drawpoint. And the ultimate objective of investigating the draw problems is to forecast the ore loss and dilution. In this paper, the rolling resistance model in the Particle Flow Code was used to simulate the effect of actual shape of different materials flowing towards a drawpoint

Local topography and structural features of discontinuities have a great effect on the movement characteristics and failure mechanisms of the unstable rock blocks of the rock slope. By taking full advantage of the geometric information contained in the multi-temporal terrestrial laser scanning (TLS) point clouds, a technique based on a roto-translation method has been developed to track and monitor

The engineered slopes along transportation routes in the Himalayan region are manifested by multiple sets of discontinuities and are vulnerable to structurally controlled failures. The hazard potential along one such route was assessed by an empirical Q-slope method. The investigated engineered slopes along the route are unstable, and the Q-slope value ranges from 0.0023 to 0.7701. By considering the

The trend today to ever increasing modelling sophistication demands that much more attention be paid by practitioners to achieving better appreciation and characterization of geology and rockmass variability, so that rock–structure interaction effects can be analysed more realistically in better calibrated models. This paper is thus directed towards focussing attention on risk-based geological characterization

Success of a hydraulic fracturing operation depends on the height and width of the induced fractures. One of the critical components controlling fracture size is fracture toughness of the formation. In this work, mode I fracture toughness of Berea Sandstone and Mancos Shale is measured by combining semi-circular bend test (SCB) and digital image correlation (DIC). Experiments were carried out in different

Firmness is one of the most important physical properties of rock, and indicates the rock’s ability to resist damage. It has considerable relevance to mining, blasting, tunneling, construction, and other engineering fields. In this study, the fractal particle-size-distribution theory was used to calculate the surface areas of coal particles after impact crushing. Combining the surface area with the

Laboratory hydraulic fracturing tests on cubic granite specimens with a side length of 100 mm were performed under true triaxial stress conditions combined with acoustic emission monitoring. Six different injection schemes were applied to investigate the influence of the injection scheme on hydraulic performance and induced seismicity during hydraulic fracturing. Three of these schemes are injection

The influence of tectonic, geostatic, and mining stresses on coal and gas outburst (CGO) becomes more obvious with increasing mining depth. The limitations of general experimental methods and test systems hinder the direct observation and characterization of the dynamic responses of the multi-physical parameters associated with CGO. In this study, a custom-made large-scale physical simulation test

Rock breaking using conical picks is a complex process affected by several factors; its performance is directly related to the excavation rate of rock tunnels, which is important in terms of the economic benefits and social impact of a project. This study investigates the effects of cutting depth and water pressure on rock breaking performance using a conical pick assisted by an abrasive water jet

The establishment of spatial correlation among scattering acoustic emission (AE) signals has great potential applied into a deep analysis of triaxial compression behaviors by the AE monitoring technology. Taking the randomly distributed AE signal could as the cube cluster by an introduction of covering strategy from the percolation theory, the quantitative evaluation of spatial correlation instead

Damaged rock mass contains a great number of microstructures and defects at various scales, which could influence wave propagation significantly. In this paper, investigation of low-amplitude stress wave attenuation in rocks with different damage degrees was undertaken to determine the effects of parameters including damage degree, heterogeneity and type of waveforms on wave propagation, attenuation

The impact of blast vibrations on cement-grouted rock is an unresolved challenge in construction projects where blasting is conducted near the grouted areas. This study investigates the blast vibration resistance of cement-grouted rock using both theoretical and experimental approaches. An analytical model is first presented based on structural characteristics and mechanical properties to describe

The anelastic properties of porous rocks depend on the pore characteristics, specifically, the pore aspect ratio and the pore fraction (related to the soft porosity). At high frequencies, there is no fluid pressure communication throughout the pore space and the rock becomes stiffer than at low frequencies, where the pore pressure is fully equilibrated. The models considered here include explicit pore

Rock masses that have a well-defined structure may also present a remarked in situ stress anisotropy; thus, the misalignment of a tunnel with the geostatic principal stresses and/or with the principal axes of material anisotropy is very likely. Analytical solutions for tunnels in transversely anisotropic rock available in the literature assume alignment of the tunnel with the geostatic principal stresses

The constant mi is a fundamental parameter required in the Hoek–Brown (H–B) failure criterion for estimating rock strength. Triaxial tests for the calculation of this constant are time-consuming and expensive. In this paper, a new perspective is presented for the physical meaning of the parameter mi of the H–B model in consideration of the contact friction coefficient. A correlation between the contact

Thermal fracturing in reservoir rocks can cause significant increase in permeability. The change in permeability due to fracturing was predicted using the change in elastic wave velocity, density, and elastic moduli. Westerly granite samples were thermally treated to 250, 450, 650 and 850 °C. Increasing the temperature produces an increase in fracture length, aperture and density that is isotropically

Numerous cases of casing failure have been reported worldwide. Depletion-induced compaction is one of the main factors that may cause casing failure. Stress perturbation in salt layers may accommodate rock flow which endangers the stability of cased wells. Besides, poor cementing jobs are recognized as one of the wellbore instability causes. These factors need to be considered to determine the mechanism

Gas sorption-induced coal deformation is one of the primary geomechanics effect in coalbed methane (CBM) engineering. Coal is known to have transversely isotropic properties because of its cleat structure. We propose a new theoretical approach to modeling the strain behavior of bulk coal by including sorption-induced matrix shrinkage/swelling strain, cleat volume strain and matrix mechanical strain

Knowledge regarding microseismic characteristics associated with longwall coal mining is crucial in evaluating the potential for underground mining hazards. Although microseismicity is induced by mining activities, it still remains uncertain as to what extent mining activities influence the spatial, temporal, and magnitude characteristics of microseismicity. To establish a thorough understanding of

Several experimental studies, carried out on anisotropic rocks, have evidenced that even though strains, due to isotropic loading and/or internal fluid pressure, are strongly anisotropic, the resulting Biot’s tensor is almost isotropic. Those results were found on two different rocks: a clay rock (France—Bure argillite) and a sandstone from the Vosges region (France). Such (a priori) surprising results

Dilatancy controlled gas flow is characterized by a series of gas pressure-induced dilatant pathways in which the pathway aperture is a function of the effective stress within the solid matrix. In this paper, a three-dimensional hydro-mechanical model is presented to simulate the gas migration in initially saturated claystone with considerable anisotropy. The governing equations including mass conservation

Underground mining or tunnelling activity is always associated with the composite geological formations. The mechanical properties of layered composite coal–rock subjected to true triaxial stress conditions are significantly different from those under conventional triaxial or uniaxial stress conditions. In this work, we conducted a series of true triaxial tests using the self-developed true-triaxial

Near-surface buckling of horizontally laminated sedimentary rock has been reported to occur in Ontario, Canada and the Upper Midwestern U.S. where high horizontal in situ stresses occur. Often referred to as ‘pop ups’, these buckling events typically occur suddenly and are commonly accompanied by a rapid energy release akin to rock bursting. In recent years, this mode of instability has become a concern

When rock salt is subjected to discontinuous fatigue, time intervals (periods during which the stress remains constant) can accelerate plastic deformation and reduce the fatigue life due to the internal residual stress generated between various defects and the host material. However, the time interval effect on rock salt in a three-dimensional stress state has rarely been investigated despite its great

This experimental study is dedicated to the measurements of gas permeability under confinement and to preliminary characterizations of salt rock poromechanical behavior. Salt porosity and permeability under loading are recorded either with argon or hydrogen gas. Permeability measurements carried out with both gases led to similar values. Poromechanical effects occur but they are weak and strongly dependent

Hydraulic fracturing is widely used in the exploitation of unconventional reservoirs, such as shale gas and tight gas. However, a full understanding of the activation of natural fractures, prediction of fracture growth, distribution of proppant, and network fracture system effectiveness remain unresolved. The onset of fracturing in the media requires energy and this is due to the buildup of pressure

This paper addresses the problem of the stability of structures on calcareous rocks due to long-term weathering processes. The case study consists of a building resting on a calcarenite rock formation where two abandoned man-made caves exist directly under the structure. The boundaries of the caves were exposed to a slightly acidic environment inducing time-dependent weathering. Analyses were performed

Understanding the temperature-dependent shear behaviors of rock discontinuity would be critical for evaluating the stability of deep underground engineering structure. However, there are few documents available in the literature. In this study, a number of direct shear tests were performed on granite discontinuities with equal/similar joint roughness coefficient (JRC) after high temperatures from room

Mechanical parameters of rock mass in mining engineering feature the characteristics of spatial variability and time decay, and it plays an important role in the slope stability analysis. The mechanical behaviour of rock engineering in low in-situ stress condition is highly affected by the rock mass quality. In this paper, the distribution of geological strength index (GSI) was obtained by geostatistics-based

Slate frequently encountered in numerous engineering applications basically exhibits significant anisotropies in terms of physico-mechanical properties due to the presence of well-developed foliation structures. The objective of this study is to investigate the mechanisms of foliation effects on the mechanical and failure characteristics of slate in three-dimensional (3D) space under Brazilian test

Dividing rock mass homogeneous regions according to discontinuities has important engineering significance. This study proposes a multidimensional clustering analysis method for dividing rock mass homogeneous regions based on shape dissimilarities, which reflect the comprehensive properties of discontinuities. The method mainly includes four procedures: (a) division of small trace maps, (b) calculation

Tunnel squeezing is a time-dependent process that typically occurs in weak or over-stressed rock masses, significantly influencing the budget and time of tunnel construction. This paper presents a new framework to probabilistically predict the potential squeezing intensity and to dynamically update the prediction during construction based on the sequentially revealed ground information. An extensively

A set of experiments on avalanches—each one with a single particle size (monodisperse)—is presented. Experiments were performed with different flume lengths, inclinations, and roughness, for different avalanching masses and particle sizes. A transition from an inertial behavior to a frictional dominated one is observed at a particle size of 1 mm, in all cases. Taking into account the energy dissipated

New developments of an in-house hybrid code, named Modified Discrete Element Method (MDEM) are presented in the paper. The new developments are on the treatment of pre-existing and propagating fractures in quasi-brittle materials. These developments are the embedment of Linear Elastic Fracture Mechanics (LEFM) and elastic-softening crack band model -based methodologies in the MDEM and their application

Pretensioned partially encapsulated resin bolting with mesh systems (PPERBMSs) are commonly employed in underground mines, particularly for soft coal gateways requiring immediate support. However, the behavior of bolts and reinforced coals has not been explained, and supporting schemes are determined by engineering analogy and experience. Herein, two large-scale physical models of extremely soft coal

Excavation, river incision and anchor cable relaxation would result in unloading of stress in at least one direction of rock masses in caverns or slopes, and the unloading failure is prominent and it even shows remarkable tensile failure. The previous direct shear tests with constant normal stress can no longer meet these circumstances. However, the experimental study of rock shear behavior under unloading

Static elastic properties, derived from stress–strain data, and dynamic elastic properties, derived from P- and S-wave velocities, are significantly different for rocks. Most rocks are deformed nearly statically (due to tectonic forces and reservoir compaction during production of the reservoir) but static measurements are not as readily available as dynamic measurements. Hence, empirical relationships

The deformational characteristics of a set of synthetic sandstones when subjected to true triaxial stress conditions were investigated in this study. The experimental results showed that the lateral stress anisotropy (σ2 ≠ σ3) significantly affected the rock’s compressive strength, elastic modulus, inelastic deformation, dilatancy and failure mode. By increasing the intermediate principal stress (σ2)

The point load strength index is a widely used index in rock engineering, and cylindrical core and irregular shaped specimens are used in its determination. But, in mine sites, the borehole cores are cut axially into two equal parts to obtain half-cut cores and one part of these half cores is sent to laboratory for geochemical analyses. This situation causes a problem that the remaining half of the

Recent research has paid little attention to the shear damage of discontinuities with different joint wall material (DDJM). In this paper, we present an investigation on the evolution of the shear behaviour and the damage of three typical types of natural DDJM in a sliding-prone stratum of China. Experimental direct shear tests were performed on 14 pairs of natural DDJM specimens to examine the changes

Block-flexure toppling is the commonest type of failure in anti-dip bedding rock slopes. In this work, a new model called the force-transfer model (FTM) for this kind of failure is proposed, which is based on cantilever beams and limit equilibrium theory. A genetic algorithm (GA) was further employed to predict the safety factor and failure surface of the rock slope. A centrifuge test was also conducted

The application of cable bolts tends to increase in both underground mining operations and civil tunnel excavations have given its outstanding performance to support the excavation surface and hence minimise the hazards and risk of failure in the field. Understanding the mechanical behaviour of cable bolts under axial loading subjected to different field environment from analytical perspective is essential

This paper describes the results of a field investigation with the objective of evaluating the possibility to produce drone-derived 3D digital point clouds sufficiently dense and accurate to determine discontinuity surface roughness characteristics. A discontinuous rock mass in Italy was chosen as the investigation site and Structure from Motion and Multi-View Stereo techniques adopted for producing

Rock masses are typical inhomogeneous geological materials that contain many fissures and cracks. The coupling effect of the crack propagation and seepage evolution in rocks is very important to the safety of rock engineering. However, hydromechanical coupling behavior during the failure of fissured rocks has rarely been investigated. In this research, hydromechanical coupling tests are performed to

In this paper, a new safety control method of the jointed slope under blasting excavation is presented. The spatial distribution of blasting damage and time-history characteristic of dynamic stability around the joint were investigated carefully based on the secondary development of the explicit FE code, LS-DYNA. Results clearly indicated that the evolution law of damage and stability are opposite

With the increasing number of long tunnelling and urban subway constructions, mixed-face ground conditions are frequently encountered. Rock fragmentation mechanism under disc cutter cutting in TBM tunneling through the mixed-face ground is complex and can lead to engineering difficulties. During TBM tunneling in mixed-face ground with soft rock in upper layer and hard rock in the lower layer, reduction

Microwave heating is a promising technique in assisting the breakage of hard and abrasive rocks. It features rapid heating and selective heating, enabling generation of large enough thermal stresses to induce damage in rocks. This paper investigated the effect of microwave treatment on the heating rate, spatial temperature distribution, ultrasonic wave velocity, elastic modulus and load bearing capacity

This paper describes a liquid application device used in combination with a split Hopkinson pressure bar (SHPB) to perform a series of dynamic tests investigating stress wave propagation through a fully saturated rock joint under undrained conditions. The characteristics of the filling-liquid dynamic response are also analyzed. Granite is used as the experimental material for the rock joint and a dynamic

To investigate the failure mechanism of reinforced coal pillars and compare their pre- and post-reinforcement bearing capacity, a series of acoustic emission (AE)-monitored uniaxial compression tests were carried out on three types of specimens, namely coal, concrete, and concrete-encased coal. The results show that the stress–strain curve of encased coal sample shows obvious double-peaked behavior

This paper presents the results of an experimental study on the dynamic fracture behaviour of 3D printed rock-like disc specimens with various pre-existing flaw configurations under high strain rate loading. The 3D printing technology is utilized to prepare disc specimens containing a single or a pair of unfilled or filled flaws. A split Hopkinson pressure bar is employed to generate high rate loading

Fracture toughness is a critical parameter responsible for fracture initiation and propagation. Fracture toughness in shale gas reservoir, however, is highly variable because of its anisotropy and spatial variation of clay content. In this paper, a series of laboratory and numerical experiments are carried out to estimate shale fracture toughness at different bedding plane orientations with respect

Joint surface morphology has essential implications for joint shear behaviors. In this paper, constant normal load (CNL) direct shear tests were performed on 150 artificial rock joint specimens to study the joint surface degradation process under various initial joint roughness coefficient (JRCinitial), joint wall compressive strength (JCS), and normal stress (σn) values. The experimental results revealed

Nondestructive imaging techniques enable the study of failure mechanisms within physical models for a wide range of geotechnical problems. This paper presented an innovative experiment that utilized micro X-ray computed tomography (CT) and an in-house experimental apparatus to study the bearing mechanisms of model piles embedded in synthetic soft sandstone rock with regular triangular asperities subjected

An old large-scale landslide with a volume of 4.6 × 106 m3 located on the right bank of the Lancang River, Southwest China, was formed by the deep-seated toppling failure of a rock mass. The rock mass located downstream of the landslide toppled intensely with a maximum toppling depth exceeding 200 m and a volume over 1.5 × 108 m3. We studied the formation mechanism of the landslide and determined the

This study is devoted to understanding the impact of irregularly shaped rock blocks against a soil buffering layer above a rock shed via numerical simulations by discrete element method (DEM). In the DEM model, the rock block is represented by an assembly of densely packed and bonded spherical particles with the block shape reconstructed from the laser scanning results of a real rock block. The soil

Characterising the size-dependent behaviour of rock has been a significant challenge in rock engineering particularly during the design of structures on or within a rock mass. Generally, the mechanical characterisation of rock starts at the laboratory scale where the intact rock is tested and then the resulting data is extrapolated to the field conditions using a suitable size effect model. Despite

From blasting to downstream, processes are linked through the continuous reduction of the size of the rock. The effect of blasting is traditionally limited to fragmentation, although effects on crushing and grinding are also recognized and examined in the paper. Fragmentation prediction methods are reviewed to identify issues that need to be addressed in engineering models to improve the accuracy of