Engineering › Mechanics of Materials

Rock Mechanics and Modeling

Works Count: 56610

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Description

This cluster of papers covers advances in rock mechanics and engineering, including topics such as fracture behavior, acoustic emission monitoring, numerical modelling, brittle failure, damage propagation, dynamic behavior, compressive strength estimation, tunnel design, and geomechanics.

Keywords

Rock Mechanics; Fracture; Acoustic Emission; Numerical Modelling; Brittle Failure; Damage Propagation; Dynamic Behavior; Compressive Strength; Tunnel Design; Geomechanics

A Model for the Mechanics of Jointed Rock

1968-05-01

Richard E. Goodman , Robert L. Taylor , Tor L. Brekke

The representation of discontinuities in analysis of blocky rock is discussed. A linkage type element is developed for addition of rock joint stiffness to the structural stiffness matrix describing the … The representation of discontinuities in analysis of blocky rock is discussed. A linkage type element is developed for addition of rock joint stiffness to the structural stiffness matrix describing the behavior of a system of rock blocks and joints. Several basic problems of jointed rock are studied. These examples demonstrate the marked influence joints may have on the stress distribution, displacements, and failure pattern of an underground opening or other structures in jointed rock. A new classification of joints is introduced, based on the application of the joint element to finite element analysis of structures in jointed rock. Normal stiffness, tangential stiffness, and shear strength are used as parameters in the classification system. The methods discussed in this paper allow a jointed rock mass to be treated as a system of blocks and links. Just as analysis of a reinforced concrete building requires detailed knowledge of the behavior of concrete alone and steel alone, the joint stiffness approach calls for and uses detailed description of the behavior of rock blocks and rock joints independently.

Crack classification in concrete based on acoustic emission

2010-06-10

Kentaro Ohno , Masayasu Ohtsu

The role of acoustic emission in the study of rock fracture

1993-12-01

D. A. Lockner

Strength, deformation and conductivity coupling of rock joints

1985-06-01

Nick Barton , Stavros Bandis , Khosrow Bakhtar

A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials

2013-09-12

Qianbing Zhang , Jian Zhao

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Review of a new shear-strength criterion for rock joints

1973-01-01

Nicholas Barton

Brittle microtectonics: principles and practice

1985-01-01

P.L. Hancock

A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering

2003-03-25

Lanru Jing

Fundamentals of rock joint deformation

1983-12-01

Stavros Bandis , A.C. Lumsden , Nick Barton

Seismic velocities in dry and saturated cracked solids

1974-12-10

Richard J. O’Connell , Bernard Budiansky

The elastic moduli of a solid permeated with an isotropic distribution of flat cracks have been calculated from the energy of a single crack by use of a self-consistent approximation. … The elastic moduli of a solid permeated with an isotropic distribution of flat cracks have been calculated from the energy of a single crack by use of a self-consistent approximation. The results are applicable for a dense network of cracks and give physically reasonable results up to the point that the shear modulus vanishes. Results for both circular and elliptical cracks are essentially the same if the crack density is characterized by 2N〈A2/P〉/π, where N is the number of cracks per unit volume, A is the area of crack, and P is the perimeter of cracks; for circular cracks of radius a this becomes N〈a3〉. This crack density parameter can be related quantitatively to crack traces observed in thin section. Results for completely dry or saturated cracks, for mixtures of dry and saturated cracks, and for cracks saturated with a compressible fluid are presented. For all cases, both seismic wave velocities decrease with increasing crack density. The velocity ratio VP/VS decreases for dry cracks and increases for saturated cracks. For the analysis of data a plot of VP/VS versus VS uniquely specifies the crack density. Comparison of the theory with wave velocities measured in laboratory rock samples demonstrates its validity for large crack densities. Interpretation of velocity changes before the San Fernando earthquake indicates that the region contained a substantial density of cracks at all times, that the anomalous decrease in VP/VS was due to the vaporization of pore fluid in nearly all of the previously saturated cracks without the introduction of new dry cracks, and that during the period of the recovery of the velocities to previous values the number of cracks in the region away from the epicentral zone decreased as they were resaturated, whereas the crack density increased following resaturation in the epicentral zone. Such use of the theoretical results may be useful in further investigations of preseismic phenomena.

Continuum Damage Theory—Application to Concrete

1989-02-01

Jacky Mazars , Gilles Pijaudier‐Cabot

This paper presents a review of the different models for concrete based on continuum damage theory, formulated at the Laboratoire de Mécanique et Technologie (Cachan, France). Derived in the framework … This paper presents a review of the different models for concrete based on continuum damage theory, formulated at the Laboratoire de Mécanique et Technologie (Cachan, France). Derived in the framework of the thermodynamics of irreversible processes, each formulation is based on physical observation. Induced anisotropy, ductile behavior, and directional effects such as the closure of cracks are discussed and adequate damage models are proposed. Finally, the numerical implementations performed give a good description of the failure process as well as an accurate prediction of the behavior of concrete and reinforced concrete structures.

Empirical estimation of rock mass modulus

2005-08-16

E. Hoek , Mark S. Diederichs

Numerical simulation of progressive rock failure and associated seismicity

1997-02-01

Chuman Tang

Limits on lithospheric stress imposed by laboratory experiments

1980-11-10

W. F. Brace , D. L. Kohlstedt

Laboratory measurements of rock strength provide limiting values of lithospheric stress, provided that one effective principal stress is known. Fracture strengths are too variable to be useful; however, rocks at … Laboratory measurements of rock strength provide limiting values of lithospheric stress, provided that one effective principal stress is known. Fracture strengths are too variable to be useful; however, rocks at shallow depth are probably fractured so that frictional strength may apply. A single linear friction law, termed Byerlee's law, holds for all materials except clays, to pressures of more than 1 GPa, to temperatures of 500°C, and over a wide range of strain rates. Byerlee's law, converted to maximum or minimum stress, is a good upper or lower bound to observed in situ stresses to 5 km, for pore pressure hydrostatic or subhydrostatic. Byerlee's law combined with the quartz or olivine flow law provides a maximum stress profile to about 25 or 50 km, respectively. For a temperature gradient of 15°K/km, stress will be close to zero at the surface and at 25 km (quartz) or 50 km (olivine) and reaches a maximum of 600 MPa (quartz) or 1100 MPa (olivine) for hydrostatic pore pressure. Some new permeability studies of crystalline rocks suggest that pore pressure will be low in the absence of a thick argillaceous cover.

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Some new Q-value correlations to assist in site characterisation and tunnel design

2002-02-01

Nick Barton

The shear strength of rock joints in theory and practice

1977-12-01

Nick Barton , Vishnu D. Choubey

A study of brittle rock fracture in laboratory compression experiments

1970-09-01

W.R. Wawersik , C. Fairhurst

Conditions for the localization of deformation in pressure-sensitive dilatant materials

1975-12-01

John W. Rudnicki , J. R. Rice

Microcracks in rocks: A review

1983-12-01

Robert L. Kranz

The failure of brittle solids containing small cracks under compressive stress states

1986-03-01

Michael F. Ashby , S. D. Hallam

Compression‐induced microcrack growth in brittle solids: Axial splitting and shear failure

1985-03-10

Hideyuki Horii , Sia Nemat‐Nasser

Micromechanisms of rock failure (axial splitting and shear failure) are examined in light of simple mathematical models motivated by microscopic observations. The elasticity boundary value problem associated with cracks growing … Micromechanisms of rock failure (axial splitting and shear failure) are examined in light of simple mathematical models motivated by microscopic observations. The elasticity boundary value problem associated with cracks growing from the tips of a model flaw is solved. It is shown that under axial compression, tension cracks nucleate at the tips of the preexisting model flaw, grow with increasing compression, and become parallel to the direction of the maximum far‐field compression. When a lateral compression also exists, the crack growth is stable and stops at some finite crack length. With a small lateral tension, on the other hand, the crack growth becomes unstable after a certain crack length is attained. This is considered to be the fundamental mechanism of axial splitting observed in uniaxially compressed rock specimens. To model the mechanism of shear failure, a row of suitably oriented model flaws is considered and the elasticity boundary value problem associated with the out‐of‐plane crack growth from the tips of the flaws is solved. It is shown that for a certain overall orientation of the flaws the growth of the out‐of‐plane cracks may become unstable, leading to possible macroscopic faulting. On the basis of this model the variations of the “ultimate strength” and the orientation of the overall fault plane with confining pressure are estimated, and the results are compared with published experimental data. In addition, the results of a set of model experiments on plates of Columbia resin CR39 containing preexisting flaws are reported. These experiments are specifically designed in order to show the effect of confining pressure on the crack growth regime. The experiments seem to support qualitatively the analytical results.

The transition from brittle faulting to cataclastic flow in porous sandstones: Mechanical deformation

1997-02-10

Teng‐fong Wong , Christian David , Wenlu Zhu

Triaxial compression experiments were conducted to investigate the inelastic and failure behavior of six sandstones with porosities ranging from 15% to 35%. A broad range of effective pressures was used … Triaxial compression experiments were conducted to investigate the inelastic and failure behavior of six sandstones with porosities ranging from 15% to 35%. A broad range of effective pressures was used so that the transition in failure mode from brittle faulting to cataclastic flow could be observed. In the brittle faulting regime, shear‐induced dilation initiates in the prepeak stage at a stress level C ' which increases with effective mean stress. Under elevated effective pressures, a sample fails by cataclastic flow. Strain hardening and shear‐enhanced compaction initiates at a stress level C * which decreases with increasing effective mean stress. The critical stresses C ' and C * were marked by surges in acoustic emission. In the stress space, C * maps out an approximately elliptical yield envelope, in accordance with the critical state and cap models. Using plasticity theory, the flow rule associated with this yield envelope was used to predict porosity changes which are comparable to experimental data. In the brittle faulting regime the associated flow rule predicts dilatancy to increase with decreasing effective pressure in qualitative agreement with the experimental observations. The data were also compared with prediction of a nonassociative model on the onset of shear localization. Experimental data suggest that a quantitative measure of brittleness is provided by the grain crushing pressure (which decreases with increasing porosity and grain size). Geologic data on tectonic faulting in siliciclastic formations (of different porosity and grain size) are consistent with the laboratory observations.

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Permeability of granite under high pressure

1968-03-15

W. F. Brace , J. B. Walsh , William Frangos

Two Parameter Fracture Model for Concrete

1985-10-01

Yeou‐Shang Jenq , Surendra P. Shah

Attempts to apply linear elastic fracture mechanics (LEFM) to concrete have been made for several years. Several investigators have reported that when fracture toughness, Klc, is evaluated from notched specimens … Attempts to apply linear elastic fracture mechanics (LEFM) to concrete have been made for several years. Several investigators have reported that when fracture toughness, Klc, is evaluated from notched specimens using conventional LEFM (measured peak load and initial notch length) a significant size effect is observed. This size effect has been attributed to nonlinear slow crack growth occurring prior to the peak load. A two parameter fracture model is proposed to include this nonlinear slow crack growth. Critical stress intensity factor, KIcS, is calculated at the tip of the effective crack. The critical effective crack extension is dictated by the elastic critical crack tip opening displacement, CTODc. Tests on notched beam specimens showed that the proposed fracture criteria to be size independent. The proposed model can be used to calculate the maximum load (for Mode I failure) of a structure of an arbitrary geometry. The validity of the model is demonstrated by an accurate simulation of the experimentally observed results of tension and beam tests.

A description of micro- and macroscale damage of concrete structures

1986-01-01

Jacky Mazars

An exact effective stress law for elastic deformation of rock with fluids

1971-09-10

Amos Nur , J. D. Byerlee

Some basic stress diffusion solutions for fluid‐saturated elastic porous media with compressible constituents

1976-05-01

J. R. Rice , M. P. Cleary

This is a study of the formulation, some basic solutions, and applications of the Biot linearized quasistatic elasticity theory of fluid‐infiltrated porous materials. Whereas most previously solved problems are based … This is a study of the formulation, some basic solutions, and applications of the Biot linearized quasistatic elasticity theory of fluid‐infiltrated porous materials. Whereas most previously solved problems are based on idealizing the fluid and solid constituents as separately incompressible, full account is taken here of constituent compressibility. Previous studies are reviewed and the Biot constitutive equations relating strain and fluid mass content to stress and pore pressure are recast in terms of new material parameters, more directly open to physical interpretation as the Poisson ratio and induced pore pressure coefficient in undrained deformation. Different formulations of the coupled deformation/diffusion field equations and their analogues in coupled thermoelasticity are discussed, and a new formulation with stress and pore pressure as basic variables is presented that leads, for plane problems, to a convenient complex variable representation of solutions. The problems solved include those of the suddenly introduced edge dislocation and concentrated line force and of the suddenly pressurized cylindrical and spherical cavity. The dislocation solution is employed to represent that for quasi‐static motions along a shear fault, and a discussion is given, based on fracture mechanics models for fault propagation, of phenomena involving coupled behavior between the rupturing solid and its pore fluid, which could serve to stabilize a fault against rapid spreading. Also, the solution for a pressurized cylindrical cavity leads to a time‐dependent stress field near the cavity wall, and its relevance to time effects in the inception of hydraulic fractures from boreholes, or from drilled holes in laboratory specimens, is discussed. Various limiting cases are identified, and numerical values of the controlling porous media elastic parameters are given for several rocks.

The progressive fracture of Lac du Bonnet granite

1994-12-01

C. Derek Martin , N. Chandler

Revisiting brittle fracture as an energy minimization problem

1998-08-01

Gilles A. Francfort , Jean‐Jacques Marigo

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A clumped particle model for rock

2007-04-18

N. Cho , C. Derek Martin , David C. Sego

Practical estimates of rock mass strength

1997-12-01

E. Hoek , E.T. Brown

The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring; 1974-2006

2009-02-01

A. W. Hatheway

Book Review| February 01, 2009 The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring; 1974–2006 Allen W. Hatheway Allen W. Hatheway 110256 Stoltz Drive, Rolla, MO 65401 Search … Book Review| February 01, 2009 The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring; 1974–2006 Allen W. Hatheway Allen W. Hatheway 110256 Stoltz Drive, Rolla, MO 65401 Search for other works by this author on: GSW Google Scholar Author and Article Information Allen W. Hatheway 110256 Stoltz Drive, Rolla, MO 65401 Publisher: Association of Environmental & Engineering Geologists First Online: 02 Mar 2017 Online ISSN: 1558-9161 Print ISSN: 1078-7275 © 2007 Association of Engineering Geologists Environmental & Engineering Geoscience (2009) 15 (1): 47–48. https://doi.org/10.2113/gseegeosci.15.1.47 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Allen W. Hatheway; The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring; 1974–2006. Environmental & Engineering Geoscience 2009;; 15 (1): 47–48. doi: https://doi.org/10.2113/gseegeosci.15.1.47 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Many engineering geologists and geological engineers have a vested interest in the broad spectrum of professional activities that constitute "rock engineering." Important contributions to this greater body of knowledge have been provided by the fine, worldwide efforts of the International Society for Rock Mechanics (ISRM) over the past 34 years. While much of the published literature in the field is and has been theoretical, perhaps the larger part is of direct interest and use to practitioners. This long-needed revised compendium of the suggested methods for gathering site information of use to engineers designing structures on and in rock stands at... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Subcritical crack growth in geological materials

1984-06-10

Barry Kean Atkinson

A review is presented of the experimental data on subcritical crack growth in geological materials. The main parameters describing subcritical crack growth are the critical stress intensity factor K c … A review is presented of the experimental data on subcritical crack growth in geological materials. The main parameters describing subcritical crack growth are the critical stress intensity factor K c , the subcritical crack growth limit K o , and the stress intensity factor‐crack velocity (K‐v) relationship between K o and K c . The K‐v data are presented in terms of an equation in which the crack velocity depends on stress intensity factor raised to a power n because this is common practice in experimental studies. These data are presented as tables and in synoptic diagrams. For silicates the value of n increases as the environment becomes depleted in hyroxyl species and with increase in the microstructural complexity of the solid. Values of n as low as 9.5 have been found for tensile cracking of quartz in basic environments and as high as 170 for tensile cracking of basalt in moist air. Insufficient experimental data are available to predict subcritical crack growth behavior at depth in the earth's crust without major extrapolations of the data base. Schematic outlines are presented, therefore, of the probable influence on subcritical crack growth of some key parameters in the crustal environment. These include stress intensity factor, temperature, pressure, activity of corrosive environmental agent, microstructure, and residual strains. In addition, a discussion is presented of the likely magnitude of the subcritical crack growth limit. For stress corrosion tensile crack growth of quartz a limit of approximately 0.2 of the critical stress intensity factor is inferred from theoretical calculations. Further problems discussed with regard to the extrapolation of experimental data to crustal conditions include the choice of a suitable equation to describe crack growth and the magnitude of parameters in these equations. A brief discussion of the double torsion testing method is presented in order to aid the interpretation of experimental results because it is almost the sole method used to study subcritical cracking in rocks.

Dilatancy in the fracture of crystalline rocks

1966-08-15

W. F. Brace , Bartlett W. Paulding , Christopher H. Scholz

Volume changes of a granite, a marble, and an aplite were measured during deformation in triaxial compression at confining pressure of as much as 8 kb. Stress-volumetric strain behavior is … Volume changes of a granite, a marble, and an aplite were measured during deformation in triaxial compression at confining pressure of as much as 8 kb. Stress-volumetric strain behavior is qualitatively the same for these rocks and a wide variety of other rocks and concrete studied elsewhere. Volume changes are purely elastic at low stress. As the maximum stress becomes one-third to two-thirds the fracture stress at a given pressure, the rocks become dilatant; that is, volume increases relative to elastic changes. The magnitude of the dilatancy, with a few exceptions, ranges from 0.2 to 2.0 times the elastic volume changes that would have occurred were the rock simply elastic. The magnitude of the dilatancy is not markedly affected by pressure, for the range of conditions studied here. For granite, the stress at which dilatancy was first detected was strongly time dependent; the higher the loading rate the higher the stress. Dilatancy, which represents an increase in porosity, was traced in the granite to open cracks which form parallel with the direction of maximum compression.

Rupture velocity of plane strain shear cracks

1976-11-10

D. J. Andrews

Propagation of plane strain shear cracks is calculated numerically by using finite difference equations with second-order accuracy. The rupture model, in which stress drops gradually as slip increases, combines two … Propagation of plane strain shear cracks is calculated numerically by using finite difference equations with second-order accuracy. The rupture model, in which stress drops gradually as slip increases, combines two different rupture criteria: (1) slip begins at a finite stress level; (2) finite energy is absorbed per unit area as the crack advances. Solutions for this model are nonsingular. In some cases there may be a transition from rupture velocity less than Rayleigh velocity to rupture velocity greater than shear wave velocity. The locus of this transition is surveyed in the parameter space of fracture energy, upper yield stress, and crack length. A solution for this model can be represented as a convolution of a singular solution having abrupt stress drop with a ‘rupture distribution function.’ The convolution eliminates the singularity and spreads out the rupture front in space-time. If the solution for abrupt stress drop has an inverse square root singularity at the crack tip, as it does for sub-Rayleigh rupture velocity, then the rupture velocity of the convolved solution is independent of the rupture distribution function and depends only on the fracture energy and crack length. On the other hand, a crack with abrupt stress drop propagating faster than the shear wave velocity has a lower-order singularity. A supershear rupture front must necessarily be spread out in space-time if a finite fracture energy is absorbed as stress drops.

The shear strength of rock and rock joints

1976-09-01

Nick Barton

A discrete numerical model for granular assemblies

1979-03-01

Peter Cundall , Otto D. L. Strack

The distinct element method is a numerical model capable of describing the mechanical behaviour of assemblies of discs and spheres. The method is based on the use of an explicit … The distinct element method is a numerical model capable of describing the mechanical behaviour of assemblies of discs and spheres. The method is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the particles modelled particle by particle. The main features of the distinct element method are described. The method is validated by comparing force vector plots obtained from the computer program BALL with the corresponding plots obtained from a photoelastic analysis. The photoelastic analysis used for the comparison is the one applied to an assembly of discs by De Josselin de Jong and Verruijt (1969). The force vector diagrams obtained numerically closely resemble those obtained photoelastically. It is concluded from this comparison that the distinct element method and the program BALL are valid tools for research into the behaviour of granular assemblies. La méthode des éléments distincts est un modèle numérique capable de décrire le comportement mécanique de l'assemblage de disques et de sphères. La méthode est basée sur l'utilisation d'un système numérique explicite dans lequel l'interaction des particules est contrôlée contact par contact et le mouvement des particules simulé particule par particule. Les caracteristiques principales de la méthode des eléments distints sont décrites. La méthode est validée en comparant les tracés de vecteur de force obtenus par le programme sur ordicateur BALL avec les tracés correspondants obtanus a l'aide d'une analyse photo-élastique. L'analyse photo-élastique utilisée pour la comparaison est celle appliquée sur un assemblage de disques par De Josselin de Jong et Verruijt (1969). Les diagrammes de vecteur de force obtenus numériquement sont très voisins de ceux obtenus photo-élastiquement. Cette comparaison permet de conclure que la methode des éléments distincts et le programme BALL sont des instruments valables pour la recherche du comportement des assemblages granulaires.

The crack–seal mechanism of rock deformation

1980-03-01

John G. Ramsay

The effect of cracks on the compressibility of rock

1965-01-15

J. B. Walsh

Unified Theory of Thermal Shock Fracture Initiation and Crack Propagation in Brittle Ceramics

1969-11-01

D. P. H. Hasselman

A fracture‐mechanical theory is presented for crack propagation in brittle ceramics subjected to thermal shock. The criteria of crack stability are derived for a brittle solid uniformly cooled with triaxially … A fracture‐mechanical theory is presented for crack propagation in brittle ceramics subjected to thermal shock. The criteria of crack stability are derived for a brittle solid uniformly cooled with triaxially constrained external boundaries. Thermal stress crack instability occurs between two values of critical crack length. For short initial crack length, crack propagation occurs kinetically, with the total area of crack propagation proportional to the factor S t 2 (1‐2 v )/EG, where S t is tensile strength, v is Poisson's ratio, E is Young's modulus, and G is surface fracture energy. Under these conditions the newly formed crack is subcritical and requires a finite increase in temperature difference before propagation will proceed. For long initial crack length, crack propagation occurs in a quasi‐static manner and can be minimized by maximizing the thermal stress crack stability parameter R st = [G/α 2 E ] 1/2 , where α is the coefficient of thermal expansion. For heterogeneous brittle solids, such as porous refractories, the concept of an “effective flaw length” is introduced and illustrated on the basis of experimental data in the literature. The relative change in strength of a brittle solid as a function of increasing severity of thermal shock is estimated. Good qualitative agreement with literature data is found.

Size Effect in Blunt Fracture: Concrete, Rock, Metal

1984-04-01

Zdeněk P. Bažant

The fracture front in concrete, as well as rock, is blunted by a zone of microcracking, and in ductile metals by a zone of yielding. This blunting causes deviations from … The fracture front in concrete, as well as rock, is blunted by a zone of microcracking, and in ductile metals by a zone of yielding. This blunting causes deviations from the structural size effect known from linear elastic fracture mechanics (LEFM). The size effect is studied first for concrete or rock structures, using dimensional analysis and illustrative examples. Fracture is considered to be caused by propagation of a crack band that has a fixed width at its front relative to the aggregate size. The analysis rests on the hypothesis that the energy release caused by fracture depends on both the length and the area of the crack band. The size effect is shown to consist in a smooth transition from the strength criterion for small sizes to LEFM for large sizes, and the nominal stress σN at failure is found to decline as (1+λ/λ0)-1/2 in which λ0=constant and λ=relative structure size. This function is verified by Walsh's test data. If reinforcement is present at the fracture front and behaves elastically, the decline of σN is of the same type but is shifted to larger sizes; however, if the reinforcement yields, the decline of σN stops. It is also noted that some known size effects which have been attributed to random strength variations within the structure should be explained by fracture mechanics, which gives a very different extrapolation to large structures. Finally, exploiting the fact that in metals the size of the yielding zone at the fracture front is approximately constant, it is shown by dimensional analysis that elastic‐plastic fracture causes a similar size effect.

Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations

2004-04-10

Ming Cai , Peter Kaiser , Y. Tasaka +3 more

A bonded-particle model for rock

2004-12-01

D.O. Potyondy , Peter Cundall

Fracture coalescence in rock-type materials under uniaxial and biaxial compression

1998-10-01

Antonio Bobet , Herbert H. Einstein

Mechanism of brittle fracture of rock

1967-10-01

Z.T. Bieniawski

THEORETICAL DISPLACEMENTS AND STRESSES NEAR FRACTURES IN ROCK: WITH APPLICATIONS TO FAULTS, JOINTS, VEINS, DIKES, AND SOLUTION SURFACES

1987-01-01

David D. Pollard , P. Segall

The Hoek–Brown failure criterion and GSI – 2018 edition

2018-08-08

E. Hoek , E.T. Brown

The Hoek–Brown criterion was introduced in 1980 to provide input for the design of underground excavations in rock. The criterion now incorporates both intact rock and discontinuities, such as joints, … The Hoek–Brown criterion was introduced in 1980 to provide input for the design of underground excavations in rock. The criterion now incorporates both intact rock and discontinuities, such as joints, characterized by the geological strength index (GSI), into a system designed to estimate the mechanical behaviour of typical rock masses encountered in tunnels, slopes and foundations. The strength and deformation properties of intact rock, derived from laboratory tests, are reduced based on the properties of discontinuities in the rock mass. The nonlinear Hoek–Brown criterion for rock masses is widely accepted and has been applied in many projects around the world. While, in general, it has been found to provide satisfactory estimates, there are several questions on the limits of its applicability and on the inaccuracies related to the quality of the input data. This paper introduces relatively few fundamental changes, but it does discuss many of the issues of utilization and presents case histories to demonstrate practical applications of the criterion and the GSI system.

Experimental study on shear mechanical properties and shear stress oscillation characteristics of regular tooth-shaped concrete joints

2025-06-25

Mengtao Tian , Baohua Guo , Shengjin Cheng +3 more | Mechanics of Time-Dependent Materials

Study on the dynamic mechanical properties and crack evolution characteristics of layered gneiss with filled joints

2025-06-25

Z. L. Wang , Chuanxin Rong , Qingqing Su +1 more | Structures

The micro-shearing mechanism of the rock-concrete interface from acoustic emission using the improved Hilbert-Huang transform

2025-06-25

Zhenyu Gao , Yuan‐Shiun Chang , Fuqiang Ren | Construction and Building Materials

Size effect on mode I fracture behavior of compacted clay with different initial crack lengths

2025-06-24

Shiyuan Huang , Xuejun Wang , Bingxiang Yuan +4 more | Construction and Building Materials

Characterization of Pare Rock Mass in North East India using Various Classification systems

2025-06-24

Pawan Kumar Singh , Diganta Goswami | Journal of The Institution of Engineers (India) Series A

Rockburst grade evaluation and parameter sensitivity analysis based on SSA-PNN framework: Considering rock mass strength

2025-06-24

Xiaoyan Zhou , Yang Jiang , Zhenyi Wang +1 more | PLoS ONE

The occurrence of rockburst is closely related to the strength and stress conditions of rock mass. The Lalin Railway tunnel in China was taken as an example, the strength and … The occurrence of rockburst is closely related to the strength and stress conditions of rock mass. The Lalin Railway tunnel in China was taken as an example, the strength and stress parameters of rock mass at 22 rockburst locations were obtained by using the results of indoor and outdoor tests, including maximum in-situ stress, maximum tangential stress, uniaxial compressive strength of rock and uniaxial compressive strength of rock mass. These four parameters were then selected to form a rockburst grade evaluation index system. Furthermore, SSA (Sparrow search algorithm) and probabilistic neural network (PNN) were used to construct a rockburst grade evaluation network, and the sensitivity of rockburst grade evaluation parameters was therefore analyzed. It shows that SSA could determine the smoothness factor of PNN efficiently, and it is reasonable to use SSA-PNN framework to evaluate the rockburst grade; maximum tangential stress and uniaxial compressive strength of rock mass have the greatest influence on the accuracy of rockburst grade evaluation, followed by maximum in-situ stress, and uniaxial compressive strength of rock has the least influence on the accuracy of rockburst grade evaluation; integrated maximum in-situ stress, maximum tangential stress, uniaxial compressive strength of rock and uniaxial compressive strength of rock mass, the rockburst grade evaluation results are highly reliable. The results presented herein may provide important reference value for the rockburst grade evaluation and the selection of rockburst grade evaluation parameters.

Investigating the Scale Effect on the Compressive Strength of Marble: Influence of Specimen Size, Shape, and Loading Surfaces

2025-06-24

Adnan Qadir , Waqas Ahmed , Muhammad Yasir +3 more | Indian geotechnical journal

Study on Calibration Method of Micromechanical Parameters for Discrete Element Model of Moderately Consolidated Sandstones

2025-06-24

Wenhong Zhang , Zhengchao Ma , Hantao Zhao +4 more | Applied Sciences

The study of the mechanical properties of moderately consolidated sandstones is crucial for engineering safety assessments. As an effective research tool, the discrete element method (DEM) encounters challenges during the … The study of the mechanical properties of moderately consolidated sandstones is crucial for engineering safety assessments. As an effective research tool, the discrete element method (DEM) encounters challenges during the modeling phase, such as a large number of micromechanical parameters, low modeling efficiency, and unclear coupling mechanisms among multiple parameters. To address these issues, this paper proposes a calibration method for the micromechanical parameters of DEM models for moderately consolidated sandstones. By integrating orthogonal experimental design with a multivariate analysis of variance, the influence of micromechanical parameters on macroscopic mechanical properties is quantified, and a parameter prediction model is constructed using an intelligent dynamic regression selection mechanism, significantly improving the efficiency and accuracy of micromechanical parameter calibration. The results show that the macroscopic elastic modulus E is primarily controlled by the effective modulus (E¯), stiffness ratio (k), and particle size ratio (Rmax/Rmin), following a linear relationship. The influence of the particle size ratio decreases significantly once it exceeds a threshold value. The macroscopic uniaxial compressive strength (UCS) is dominated by cohesion (c¯) and tensile strength (σ¯c), exhibiting a polynomial relationship, where a stronger synergistic effect is generated when both parameters are at higher levels. Poisson’s ratio (μ) is significantly correlated only with the stiffness ratio (k), following a logarithmic relationship. An iterative correction method for micromechanical parameter calibration is proposed. The errors between the three groups of simulation results and laboratory test results are all less than 10%, and the crack distribution patterns show a high degree of consistency. The findings of this study provide a theoretical foundation and technical means for exploring the mechanical behavior and damage mechanism of moderately consolidated sandstones.

Hybrid Machine Learning Model for Predicting Shear Strength of Rock Joints

2025-06-24

Daxing Lei , Yaoping Zhang , Zhigang Lu +2 more | Applied Sciences

The accurate prediction of joint shear strength is crucial for rock mass engineering design and geological hazard assessment. However, traditional machine learning (ML) models often suffer from local optima and … The accurate prediction of joint shear strength is crucial for rock mass engineering design and geological hazard assessment. However, traditional machine learning (ML) models often suffer from local optima and limited generalization ability when dealing with complex nonlinear problems, thereby compromising prediction accuracy and stability. To address these challenges, this study proposes a hybrid ML model that integrates a multilayer perceptron (MLP) with the slime mold algorithm (SMA), termed the SMA-MLP model. While MLP exhibits strong nonlinear mapping capability, SMA enhances its training process through global optimization and parameter tuning, thereby improving predictive accuracy and robustness. A dataset with five input variables was constructed to evaluate the performance of the SMA-MLP model comprehensively. The proposed model was compared with other ML models. The results indicate that SMA-MLP outperforms these models in key metrics such as the root mean squared error (RMSE) and the correlation coefficient (R2), achieving an R2 of 0.97 and an RMSE as low as 0.10 MPa on the test set. Furthermore, feature importance analysis reveals that normal stress has the most significant influence on joint shear strength. This study demonstrates the superiority of SMA-MLP in predicting joint shear strength, highlighting its potential as an efficient and accurate tool for rock mass engineering analysis and providing reliable technical support for geological hazard assessment.

Investigation of Raw Material Properties of Turkoglu (Kahramanmaraş) Region Dolomites

2025-06-23

Özen Kılıç , Ahmet Mahmut KILIÇ | Geosound.

This study was carried out with the aim of determining the raw material properties of the dolomites of the Turkoglu (Kahramanmaraş) region. In this study, samples were taken from the … This study was carried out with the aim of determining the raw material properties of the dolomites of the Turkoglu (Kahramanmaraş) region. In this study, samples were taken from the dolomites of occur widely area in Turkoglu (Kahramanmaraş) and firstly, the chemical composition, mineralogical structure, petrographic properties and physico-mechanical properties of the dolomite samples were determined and secondly, calcination experiments were carried out. Calcination experiments were carried out to determine the thermal behavior of dolomites under high temperature conditions. As a result of the study, it was understood that the examined dolomite samples could be used for building materials, lime, glass and refractories production etc.

Study on the Mechanical Properties and Degradation Mechanisms of Damaged Rock Under the Influence of Liquid Saturation

2025-06-23

Bowen Wu , Jucai Chang , Jianbiao Bai +2 more | Applied Sciences

To investigate the degradation mechanisms of the surrounding rock in abandoned mine roadways used for oil storage, this study combined uniaxial compression tests with digital image correlation (DIC), scanning electron … To investigate the degradation mechanisms of the surrounding rock in abandoned mine roadways used for oil storage, this study combined uniaxial compression tests with digital image correlation (DIC), scanning electron microscopy (SEM), and other techniques to analyze the evolution of the rock mechanical properties under the coupled effects of oil–water soaking and initial damage. The results indicate that oil–water soaking induces the loss of silicon elements and the deterioration of microstructure, leading to surface peeling, crack propagation, and increased porosity of the sample. The compressive strength decreases linearly with the soaking time. Acoustic emission (AE) monitoring showed that after 24 h of soaking, the maximum ringing count rate and cumulative count decreased by 81.7% and 80.4%, respectively, compared to the dry state. As the liquid saturation increases, the failure mode transitions from tension dominated to shear failure. The synergistic effect of initial damage and oil–water erosion weakens the rock’s energy storage capacity, with the energy storage limit decreasing by 45.6%, leading to reduced resistance to external forces.

Critical grain size and shear behavior of polycrystalline rocks under confining pressure: A moment tensor-based GBM approach

2025-06-23

Zheng Yang , Qusi I. Alqawasmeh , Jinyin Ma +3 more | Computers and Geotechnics

Acoustic emission and wave velocity monitoring of rock-backfill composites: damage identification and failure characterization

2025-06-22

Yongchao Chen , Longjun Dong , Guido Maria Adinolfi +3 more | Measurement

Research on the Mechanical Behavior and Rockburst Risk of the Deep-Buried Roadway at the Stratigraphical Boundary of Different Lithologies

2025-06-22

Chaoqun Chu , Lei Xia , Shunchuan Wu +2 more | Applied Sciences

It has been found in engineering practice that the degree of rockburst risk increases when roadway excavation occurs near the stratigraphical boundary of different lithologies. This study uses the 1276 … It has been found in engineering practice that the degree of rockburst risk increases when roadway excavation occurs near the stratigraphical boundary of different lithologies. This study uses the 1276 m deep-buried roadway of a lead–zinc mine in Yunnan, China, as its engineering background. Based on a numerical analysis of this case, it investigates the mechanical behavior of surrounding rocks in different lithological formations and explores the causes of excavation-induced rockburst. Additionally, by changing the excavation strategy in a numerical simulation, the influence of the direction of roadway excavation on the degree of rockburst risk in the construction of different lithological formations is assessed. The results are summarized as follows: (1) When the tunnel passes from the C1b stratum (limestone) to the D3zg stratum (dolomite), an abnormal stress zone forms in the roof rock strata of the D3zg stratum (the lower plate of the stratum boundary). The rockburst risk level was evaluated by introducing the numerical rockburst index in this abnormal stress zone, which aligns closely with on-site rockburst investigation results. The rockburst risk is the greatest in the abnormal stress zone, which provides an external energy storage environment for the development of rockburst disasters. (2) Near the stratum boundary, the rockburst risk level when excavating from the D3zg stratum to the C1b stratum is greater than that when excavating from the C1b stratum to the D3zg stratum. The direction of tunnel excavation significantly affects the rockburst risk level during construction that crosses different lithological strata. These findings can provide a theoretical basis for the construction design of similar underground projects.

Numerical investigation on damage effect of deep hole pre-cracking roof rock and controlling rockburst

2025-06-22

Hao Qi , Anye Cao , Changbin Wang +2 more | International Journal of Coal Science & Technology

Abstract Deep hole pre-cracking blasting (DHPB) technology is the preferred means of preventing and controlling rockburst induced by hard-thick rock layers in coal mines. When DHPB is applied to hard-thick … Abstract Deep hole pre-cracking blasting (DHPB) technology is the preferred means of preventing and controlling rockburst induced by hard-thick rock layers in coal mines. When DHPB is applied to hard-thick rock layers, the insufficient knowledge about the crack extension scale under different rock properties and blasting parameters may result in undesirable pressure relief. Therefore, LS-DYNA was adopted to analyse the crack extension characteristics under the combined effect of rock tensile strength, explosive density, blasthole spacing, and decoupled coefficient. The Holmquist–Johnson–Cook model (HJC), verified by the results of blasting experiment and numerical simulation in literature, was used to characterise coal-bearing rocks. Numerical analysis was conducted to study the blasting crack extension and fractal damage for rock tensile strength, explosive densities, blasthole spacing, and decoupled coefficients. The results show that the tensile strength of rock is the key factor for blasting design. The fractal damage caused by blasting increases when the tensile strength of rock decreases. For rocks with lower tensile strength, more blasting energy is consumed by the increasing damage area in the crushed zone. Higher explosive density can promote the development of blasting cracks and increase fractal damage, but the increasing range of the crushed zone also wastes a large amount of energy. As the blasthole spacing increases, the fractal damage decreases, and the crack extension scale in the fractured zone first increases and then decreases, and eventually remains almost unchanged. An optimum interval exists for the decoupled coefficient, and the full utilization of explosive energy within the interval leads to penetrating blast cracks and smaller crushed zones. Based on the simulation results, the optimal blasting parameters for coarse sandstone were validated in the field practice. Monitoring data show that the optimized blasting significantly reduces the risk of rockburst.

Numerical Study of Surrounding Rock Damage in Deep-Buried Tunnels for Building-Integrated Underground Structures

2025-06-21

Penglin Zhang , Chong Zhang , Weitao Chen +3 more | Buildings

When deep-buried tunnels are excavated using the drill-and-blast method, the surrounding rock is subjected to combined cyclic blasting loads and excavation-induced stress unloading. Understanding the distribution characteristics of rock damage … When deep-buried tunnels are excavated using the drill-and-blast method, the surrounding rock is subjected to combined cyclic blasting loads and excavation-induced stress unloading. Understanding the distribution characteristics of rock damage zones under these conditions is crucial for the design and safety of building-integrated underground structures. This study investigates the relationship between surrounding rock damage and in situ stress conditions through numerical simulation methods. A constitutive model suitable for simulating rock mass damage was developed and implemented in the LS-DYNA (version R12) code via a user-defined material model, with parameters determined using the Hoek–Brown failure criterion. A finite element model was established to analyze surrounding rock damage under cyclic blasting loads, and the model was validated using field data. Simulations were then carried out to explore the evolution of the damage zone under various stress conditions. The results show that with increasing hydrostatic pressure, the extent of the damage zone first decreases and then increases, with blasting-induced damage dominating under lower pressure and unloading-induced shear failure prevailing at higher pressure. When the hydrostatic pressure is less than 20 MPa, the surrounding rock stabilizes at a distance greater than 12.6 m from the tunnel face, whereas at hydrostatic pressures of 30 MPa and 40 MPa, this distance increases to 29.4 m. When the lateral pressure coefficient is low, tensile failure occurs mainly at the vault and floor, while shear failure dominates at the arch waist. As the lateral pressure coefficient increases, the failure mode at the vault shifts from tensile to shear. Additionally, when the horizontal stress perpendicular to the tunnel axis (σH) is less than the vertical stress (σv), variations in the axial horizontal stress (σh) have a significant effect on shear failure. Conversely, when σH exceeds σv, changes in σh have little impact on the extent of rock damage.

An Experimental Investigation on the Microscopic Damage and Mechanical Properties of Coal Under Hygrothermal Conditions

2025-06-21

Haisen Zhao , Guichen Li , Jiahui Xu +5 more | Applied Sciences

Investigating the microstructural damage and mechanical properties of coal under deep mine hygrothermal conditions is essential for ensuring the safe and efficient extraction of coal resources. In this study, X-ray … Investigating the microstructural damage and mechanical properties of coal under deep mine hygrothermal conditions is essential for ensuring the safe and efficient extraction of coal resources. In this study, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and nanoindentation techniques were employed to examine the surface morphology and microscale mechanical properties of coal samples exposed to four environmental conditions, initial, humidified, heated, and coupled hygrothermal, under a peak indentation load of 70 mN. The results indicate that humidification led to the formation of dissolution pores and localized surface softening, resulting in a 15.9% increase in the peak indentation depth and reductions in the hardness and elastic modulus by 29.53% and 17.14%, respectively. Heating caused localized disintegration and the collapse of the coal surface, accompanied by surface hardening, with a slight 0.4% decrease in the peak indentation depth and increases in hardness and the elastic modulus by 1.32% and 1.56%, respectively. Under the coupled hygrothermal condition, numerous fine dissolution pores and microcracks developed on the coal surface, and the mechanical properties exhibited intermediate values between those observed in the humidified and heated states. Notably, the elevated temperature suppressed the moisture penetration into the coal matrix to some extent in the hygrothermal environment. A positive correlation was found between the hardness and elastic modulus, independent of the coal sample condition. The mineralogical composition significantly influenced the microscale mechanical behavior, with hard quartz minerals corresponding to lower peak indentation depths and a higher hardness, whereas soft kaolinite showed the opposite trend.

Role of microscopic heterogeneity for deformability of rock mass from drilling

2025-06-21

Xinxing Liu | Rock mechanics letters.

Heterogeneity of natural rock mass differs from most other engineering materials. Although the heterogeneity, such as macroscopic fracture, potentially contributes to the deformability of rock mass, evidence for macroscopic heterogeneity … Heterogeneity of natural rock mass differs from most other engineering materials. Although the heterogeneity, such as macroscopic fracture, potentially contributes to the deformability of rock mass, evidence for macroscopic heterogeneity from field studies has been circumstantial. We present the results of field drilling energy experiment on the rock mass of tuff, limestone and marble types that shows the evidence for the rock mass deformability from macroscopic heterogeneity caused by fracture, reflecting borehole macroscopic heterogeneity associated with drill energy. The experimental results show that the macroscopic heterogeneity is expected to vary linearly with the fracture frequency, and depends on rock types and drilling energy. The contributions of macroscopic heterogeneity for deformability of rock mass have undergone a leading role.

Experimental Investigation of Mechanical Behavior and Damage Evolution of Coal Materials Subjected to Cyclic Triaxial Loads with Increasing Amplitudes

2025-06-21

Zongwu Song , Tang Chun-an , Hongyuan Liu | Materials

As a part of the mining-induced stress redistribution process during coal mining, the repeated loading and unloading process with increasing peak stresses will cause more severe deformation and damage to … As a part of the mining-induced stress redistribution process during coal mining, the repeated loading and unloading process with increasing peak stresses will cause more severe deformation and damage to mining roadways, which is different from the findings in other underground engineering practices. Consequently, cyclic triaxial compression tests with increasing amplitudes were carried out to investigate the mechanical behavior, acoustic emission (AE) characteristics, and damage evolution of coal materials. It is found that peak deviatoric stress and axial residual strain at the failure of coal specimens increase with increasing confining pressures, while the changes in circumferential strain are not obvious. Moreover, the failure patterns of coal specimens exhibit shear failure due to the constraint of confining pressures while some local tensile cracks occur near the shear bands at both ends of the specimens. After that, the damage evolution of coal specimens was analyzed against the regularity of AE counts and energies to develop a damage evolution model. It is concluded that the damage evolution model can not only quantify the deformation and failure process of the coal specimens under cyclic loads with increasing amplitudes but also takes into account both the initial damage due to natural defects and the induced damage by the cyclic loads in previous cycles.

Effect of Gas Pressure on Energy Behavior of Coal Under Cyclic Loading and an Energy-Based Constitutive Model

2025-06-20

Hao Fan , Yu Wang | Indian geotechnical journal

Numerical modeling of effective elastic properties for heterogeneous porous media. Application to a case study of a carbonate reservoir rock sample

2025-06-20

A. Markov , Martín A. Díaz-Viera , Manuel Coronado +1 more | International Journal of Engineering Science

A statistical bonded particle model study on laboratory scale rock drilling

2025-06-20

Albin Wessling , Simon Larsson , Mathis Warlo +1 more | Computational Particle Mechanics

Abstract Rock drilling is a crucial process in many industries, one example being the mining industry, where it is used for exploration and blasting. In a typical rock drilling process, … Abstract Rock drilling is a crucial process in many industries, one example being the mining industry, where it is used for exploration and blasting. In a typical rock drilling process, the rock surface is fractured by dynamic mechanical interaction with a drill bit, resulting in rock fragments detaching from the surface. These cuttings are then transported through the borehole via water or air, and the rock fragment size is important for efficient borehole flushing. In this work, a heterogeneous bonded particle model was calibrated and applied to a laboratory scale rock drilling process. The mineral grain structure was obtained from an electron microscope scan of the rock surface, and the average grain size, volume percentage and stiffness of the three most common minerals were represented in the model. The dynamic mechanical behaviour of the rock material was obtained by conducting uniaxial compression and Brazilian disc tests in a split-Hopkinson pressure bar configuration. The results were used to calibrate the model. After the heterogeneous model was shown to be able to capture the macroscopic strengths and fracture modes of the split-Hopkinson experiments, it was used to simulate the laboratory scale rock drilling experiment, where two tool indentation depths were investigated. Here, the simulation was compared to experimental results in terms of vertical load acting on the tool, machine compliance as well as rock-cutting size distributions. The results from the simulation were in good agreement with the experimental observations.

Modelling the Cracking Mechanism of Transversely Isotropic Rocks Using a 3D Grain-Based Model: A Case Study of the Callovo-Oxfordian Claystone

2025-06-20

Juliette Michalon , Benoît Pardoen , Denis Branque +2 more | Rock Mechanics and Rock Engineering

A Robust Framework for Blast Fragmentation and Risk Mitigation: A Comparative Analysis

2025-06-20

Chandrakanta Behera , Subhamoy Ghosh , Tushar Gupta +1 more | Rock Mechanics and Rock Engineering

Mechanical Response of Soft Rock Roadways in Deep Coal Mines Under Tectonic Stress and Surrounding Rock Control Measures

2025-06-20

Anying Yuan , Chong Xu , Tian Xin | Applied Sciences

This study focuses on how rocks respond mechanically and how to keep them stable when soft rock roadways are under deep tectonic stress. It does this through a combination of … This study focuses on how rocks respond mechanically and how to keep them stable when soft rock roadways are under deep tectonic stress. It does this through a combination of theoretical analysis, numerical simulations, and field applications. We created a mechanical model of roof strata to calculate how much they would bend under both horizontal tectonic stress and their weight. This modeling helped us determine the critical yield limits. A systematic study of the angle θ between the direction of tectonic stress and the axis of the roadway showed that the concentration of horizontal stress on the roof gets stronger as θ increases, while the vertical stress on the sidewalls slowly gets weaker. The main sign of surrounding rock failure is shear damage that is most severe at the roof, floor, and shoulder angles. The maximum plastic zone depth occurs at θ = 90°. Studies that looked at both gob-side and along-roadway stages found that the two types of failure were very different, characterized by severe roof damage during roadway advancement and pronounced coal pillar instability in gob-side conditions. Based on these results, targeted support strategies were successfully used in field engineering to control deformations and provide both theoretical foundations and practical solutions for stabilizing deep soft rock roadways under tectonic stress.

The unique modified seesaw test (MST) instrument for the direct assessment of rock’s tensile strength utilizing ring-shaped specimens

2025-06-19

Parveen Kumar , Srijan Srijan , Vanita Aggarwal +1 more | Sadhana

A reliability model to predict failure behaviour of overlying strata in groundwater-rich coal mine

2025-06-19

Ruirui Li , Xiaowei Hou , Luwang Chen +3 more | International Journal of Coal Science & Technology

Abstract Coal mining in groundwater-rich coal fields will trigger failure of overlying strata, resulting in the formation of water-conducting fracture zone (WCFZ) and potentially leading to water-inrush accidents. In this … Abstract Coal mining in groundwater-rich coal fields will trigger failure of overlying strata, resulting in the formation of water-conducting fracture zone (WCFZ) and potentially leading to water-inrush accidents. In this study, a reliability model with consideration of spatial variability and uncertainty of strength parameters was proposed to predict the failure behaviour of overlying strata during coal mining in groundwater-rich coalfields. Rock strength parameters, including cohesion, internal friction angle, uniaxial tensile strength, and softening coefficient, are treated as random variables to determine the rock failure uncertainty. The experimental results of these geomechanical parameters at different positions are interpolated by the Kriging interpolation method. Spatially, the interpolated values are arranged as the average value of each random variable to demonstrate their autocorrelation. Furthermore, based on Mohr–Coulomb yield criterion, a performance function is deduced to calculate the failure probabilities of overburden rocks to evaluate the spatial scale of WCFZ. As a typical case, the failure features of adjacent overlying strata of No. 7121 mining face in Qidong Coal Mine is analyzed. The results show that the risks of water-inrush are high when the mining face advances to 260–380 m and 1120–1240 m, which aligns with both field monitoring results and borehole observation results. The proposed model holds significant implications for prevention of water-inrush accidents in groundwater-rich coal mines.

Three-Dimensional Printing Experiments and Particle-Based Meshless Numerical Investigations on the Failure Modes of Tunnel-Lining Structures Containing Fissures

2025-06-19

Shuyang Yu , Zhongqing Chen , Yifei Li +2 more | Buildings

The presence of fissures poses significant threats to tunnel-lining structures, and the interaction between tunnels and linings under complex stress conditions remains poorly understood. This study investigated the failure modes … The presence of fissures poses significant threats to tunnel-lining structures, and the interaction between tunnels and linings under complex stress conditions remains poorly understood. This study investigated the failure modes of tunnel-lining structures with prefabricated fissures via 3D-printed samples, uniaxial compression experiments using DIC technology for full-field strain monitoring, and a particle-based meshless (SPH) numerical method to simulate tunnel–fissure interactions. The results show that under uniaxial compression, three crack types (main, upper/lower side cracks) initiate from the tunnel, while only wing cracks form at pre-existing fissures; wing crack initiation suppresses upper-side cracks, whereas more lining cracks (upper, middle, lower, corner, bottom) emerge without fissure-induced propagation. Fissure orientation (β) and inclination (α) significantly affect crack distributions: β = 90° induces maximum stress concentration and asymmetric deformation, while α ≥ 45° promotes wing crack initiation and reduces lining crack density. Along with our findings, we offer design recommendations to prioritize fissure orientation in tunnel engineering and expand SPH applications for predicting crack propagation in underground structures with complex fissures.

Effects of Lithology Combination Compaction Seepage Characteristics on Groundwater Prevention and Control in Shallow Coal Seam Group Mining

2025-06-19

Kaijun Miao , Shihao Tu , Wenping Li +4 more | Applied Sciences

The mining of shallow coal seam groups triggers mine water inrush and ecological environment destruction. Effective groundwater prevention and control requires controlling the compaction and seepage characteristics (CSCs) of broken … The mining of shallow coal seam groups triggers mine water inrush and ecological environment destruction. Effective groundwater prevention and control requires controlling the compaction and seepage characteristics (CSCs) of broken rock in goaf. In this study, the CSCs of roof lithology and goaf broken rock combinations are experimentally investigated. The results indicate that, for samples with identical gradation, the percentage of void (PV) is minimized in sandstone–mudstone combinations, while PV increases with higher coal content. Initial compaction of composite samples is primarily governed by soft rock re-crushing, whereas the stable compaction stage is determined by the initial PV. Under low axial stress, the CSCs of lithological combination samples exhibit instability, with the mudstone layer reducing flow velocity by approximately 36% under equivalent compaction and seepage conditions. Particle migration, leading to the blockage of the seepage section, is an important cause of the decrease in permeability. Based on experimental findings, a stress–void–seepage coupling model is established to describe the compaction–seepage behavior of lithologic combination broken rock in shallow goafs.

3D RBSM-based mesoscale simulation on the fracture behavior of high-strength concrete under compression: considering aggregate strength grade and shape

2025-06-19

Yi Wang , Xunjie Zhang , Faxing Ding +2 more | Journal of Building Engineering

Pore-scale damage evolution in sandstone induced by fluid infiltration under various stress conditions

2025-06-19

Yongfa Zhang , Anfa Long , Arno Zang +1 more | International Journal of Rock Mechanics and Mining Sciences

Three-dimensional discrete element simulation of a transversely isotropic rock considering initial cracks

2025-06-19

Kaihui Li , Jiezhen Chen , Dongya Han +3 more | Computers and Geotechnics

Study on the effect of mining height on overburden strata movement in longwall mining

2025-06-19

Ying Ma , Qunying Wu , Yang Jin-hong +4 more | International Journal of Coal Science & Technology

Abstract The mining height of a coal seam is a critical factor influencing the detachment, collapse, and formation of the collapse angle of the strata during strata movement. To clarify … Abstract The mining height of a coal seam is a critical factor influencing the detachment, collapse, and formation of the collapse angle of the strata during strata movement. To clarify the mechanism by which mining height affects strata movement characteristics, a physical model experiment was conducted based on the geological conditions of the Panel 122104 in Caojiatan Coal Mine in Shaanxi. The experiment examined strata movement at mining heights of 1 m and 10 m, identifying differences in detachment, collapse behavior, and collapse angles under these two conditions. The results indicate the following: Delamination range directly governs collapse patterns, with higher stress concentration accelerating delamination initiation and expanding affected zones. 1 m mining height exhibits a “ superposed fixed beam” structure with lower strength compared to the “fixed beam + cantilever beam” configuration under 10 m height. A model estimating collapse step shows 9.13% average error. Strata structure dictates collapse angle mechanisms: Pseudo-plastic deformation under 1 m height determines collapse angle through vertical tensile stress boundaries, whereas 10 m height exhibits brittle fracture behavior with collapse angles approximating fracture angles. Periodic collapse volume above working face directly correlates with mine pressure intensity and is positively correlated with the caving step distance, collapse angle, and caving range. These parameters show higher values under 10 m mining height, resulting in more pronounced mine pressure manifestations compared to 1 m conditions.

Understanding mechanical behaviour of Zewan Formation limestones of Permian-Triassic age under traditional triaxial compression test

2025-06-19

Aasif Ibni Ahad , Syed Kaiser Bukhari | Journal of Earth System Science

Case study of hydraulic fracturing for coal burst risk mitigation

2025-06-19

Hongpu Kang , Xia Yongxue , Manxuan Feng +2 more | International Journal of Coal Science & Technology

Abstract Coal bursts pose significant safety and operational challenges in deep mining environments, necessitating effective mitigation strategies to address high-stress concentrations and dynamic failure risks. This study evaluated the efficacy … Abstract Coal bursts pose significant safety and operational challenges in deep mining environments, necessitating effective mitigation strategies to address high-stress concentrations and dynamic failure risks. This study evaluated the efficacy of hydraulic fracturing as a preconditioning tool at a longwall face of the Mengcun coal mine with strong coal bursts, Shaanxi Province. The program involved the systematic creation of a fracture network through high-pressure fluid injection, monitored via microseismic arrays, stress measurements, and hydrological sensors. Results demonstrated that hydraulic fracturing effectively redistributed in-situ stresses, reducing high-stress concentrations by up to 30%, lowering the frequency of high-energy microseismic events, and enhancing the stability of fractured zones. However, the presence of unfractured blind spots and interactions with pre-existing faults highlighted the need for optimized well placement and adaptive fracturing designs. These findings underscore the potential of hydraulic fracturing as a critical preconditioning tool in high-stress mining operations, which could provide a framework for improving safety and efficiency in similar geological and operational settings.

Dynamic behaviour and nonlinear ultrasonic characteristic of sandstone under intermittent cyclic impact loading

2025-06-19

Xiangyu Wang , Z.Y. Liu , Ye Wang +2 more | Engineering Fracture Mechanics

Nonlocal gradient viscoplastic analyses of interacting rate and scale effects in borehole failure

2025-06-18

Dawei Xue , Xilin Lü , Maosong Huang +1 more | Computers and Geotechnics

A finite-strain procedure for calculating fictitious support pressure of a tunnel based on a re-developed GRC and LDP considering large deformation

2025-06-18

Kai Guan , Hongping Li , Wancheng Zhu +1 more | Computers and Geotechnics

Precursory and damage characteristics of static and dynamic failures in granite under biaxial compression with different loading rates: Insight from sound signals

2025-06-18

Peifeng Li , Guoshao Su , Salvatore Martino +2 more | International Journal of Damage Mechanics

In deep rock engineering, rocks adjacent to excavation boundaries, subjected to biaxial compression, frequently encounter severe static and dynamic hazards induced by construction activities. These processes generate abundant sound signals … In deep rock engineering, rocks adjacent to excavation boundaries, subjected to biaxial compression, frequently encounter severe static and dynamic hazards induced by construction activities. These processes generate abundant sound signals associated with rock pre-failures, although the beneficial characteristics of these signals remain inadequately understood. Their potential drives us to comprehensively explore the precursory and damage characteristics of static (spalling) and dynamic (rockburst) failures in granite under biaxial compression with different loading rates using sound signals. Based on the characteristic analysis of sound signals in the time and frequency domains, we identified multiple precursors correlated with the rock failures and introduced a prediction method for determining the rock failure modes (spalling and rockburst). Subsequently, the strong effects of loading rate on the sound precursors were revealed. Moreover, the proposed sound-based damage constitutive model for granite under biaxial compression with different loading rates was proven to be feasible. Furthermore, the amplitude-frequency properties of sound signals produced by rock cracking under biaxial compression were uncovered. The research results of this study improve the prediction and warning of static-dynamic mechanisms driven rock failures under biaxial compression through sound monitoring technology.

Mechanical responses of sandstone exposed to triaxial differential cyclic loading with distinct unloading rates of confining stress: A lab scale investigation

2025-06-18

Zhengyang Song , W. H. Zhang , Z. Yu +3 more | International Journal of Coal Science & Technology

Abstract This article investigates the mechanical responses and acoustic emission (AE) characteristics of sandstone under the triaxial differential cyclic loading (DCL) at different unloading rates of confining stress. The test … Abstract This article investigates the mechanical responses and acoustic emission (AE) characteristics of sandstone under the triaxial differential cyclic loading (DCL) at different unloading rates of confining stress. The test results indicate that strength of rock specimens under different stress paths of triaxial unloading confining stress-differential cyclic loading (TUCS-DCL) can be fitted by the Mohr–Coulomb, Hoek–Brown, and Bieniawski criteria. The confining stress unloading rate can dominate the radial strain rate, while the axial DCL pattern has an unpronounced effect. The confining stress unloading rate affects the energy evolution in radial and axial directions of specimens, with the ratio of radially released energy to axially consumed energy fluctuating more significantly during the fast unloading of confining stress, the valley value of the ratio can serve as a precursor for failure. The confining stress unloading rate has no significant effect on stress–strain phase shift, while axial rapid-loading-slow-unloading can correspond to a larger magnitude of phase shift. AE signals begin to significantly increase after the confining stress is unloaded to zero, and a notable Kaiser effect is observed during cyclic loading preceding the failure.

Mechanical Response and Failure Mechanisms of Block Caving Bottom Structures Under Dynamic Conditions Induced by Slope Rockfalls

2025-06-18

Xinglong Feng , Guangquan Li , Zeyue Wang +3 more | Applied Sciences

The stability of bottom structures in block caving mines is significantly challenged by impact loads generated from large rockfalls and ore collapses on slopes. This study aims to investigate the … The stability of bottom structures in block caving mines is significantly challenged by impact loads generated from large rockfalls and ore collapses on slopes. This study aims to investigate the mechanical response and failure characteristics of bottom structures under such dynamic and cyclic loading conditions. Discrete element methods (DEMs) were employed to simulate the impact load amplitudes caused by large rockfalls on bottom structures. Specimens with identical mechanical properties to the bottom structure were fabricated at a 1:100 scale, based on the principle of similarity ratio tests. Three distinct types of impact loads were identified and analyzed: overall impact from large-scale slope collapses, localized impact from partial rock and soil mass collapses, and continuous multiple impacts from progressive slope failures. True triaxial tests were conducted to evaluate the mechanical response of the bottom structure under these loading scenarios. The results indicate that while overall and multiple impact loads from slope collapses do not lead to catastrophic failure of the bottom structure, severe damage occurs under a 100 m thickness of ore and large block impacts. Specifically, the inner walls of ore accumulation troughs peel off, and ore pillars between troughs fracture and fail. This study highlights the need for advanced experimental and numerical approaches to accurately predict the stability and failure modes of bottom structures under complex loading conditions.

New Insight into the Effect of Localised Mismatch on the Shear Strength of Rough Rock Discontinuities

2025-06-18

Olivier Buzzi , Andrew Vidler | Rock Mechanics and Rock Engineering

Abstract This paper presents the results of an experimental investigation on the shear strength of mismatched rock discontinuities. Direct shear tests were conducted on mortar replicas of three surfaces of … Abstract This paper presents the results of an experimental investigation on the shear strength of mismatched rock discontinuities. Direct shear tests were conducted on mortar replicas of three surfaces of different roughness and with increasing degrees of localised mismatch, as opposed to lateral dislocation, introduced both in areas of steep asperities (high gradients) and shallow asperities (low gradients). The peak shear strength was found to reduce with an increasing degree of mismatch in areas of high gradients and stabilises to an approximately constant value once a certain amount of mismatch, referred to as “maximum effective mismatch”, has been reached. The rougher the surface, the more pronounced the effect of mismatch. Removing even a small area of high gradients can halve the peak shear strength. In contrast, the effect of mismatch is marginal in areas of low gradients and almost inexistent on the residual shear strength. It was also found that the loss of strength due to mismatch is roughness dependent but not stress dependent. Two existing models predicting the shear strength of mismatched discontinuities were tested and found to perform poorly. Consequently, a new model was proposed, and much better predictions obtained.

On the effects of fault alignment on slip stability

2025-06-18

Yuri Fialko , Yoshihiro Kaneko | Nature

Pore fractal and damage characteristics of granite following high-temperature heating and water cooling

2025-06-18

Hongmei Gao , Lan Yong-wei , Yanlin Zhao +1 more | Acta Geotechnica

Anti-uplift stability for CAES rock caverns in Hoek-Brown rock masses considering the location of crack initiation

2025-06-18

Jia Pan , Zhi-Cheng Tang | Tunnelling and Underground Space Technology

Fracture behavior of concrete with waste ceramic coarse aggregates: Insights from digital image correlation and acoustic emission

2025-06-18

Wenlei Xu , Yantao Zhu , Lining Zhang +3 more | Construction and Building Materials

Double-Borehole Superimposed Effect of a New Non-Explosive Directional Rock-Breaking Method

2025-06-17

Quan Zhang , Manchao He , Kai Chen +6 more | Applied Sciences

Due to the difficulty of creating directional fractures efficiently and accurately with existing non-explosive rock-breaking methods, a directional fracturing technique utilizing a coal-based solid waste expansive agent, termed the instantaneous … Due to the difficulty of creating directional fractures efficiently and accurately with existing non-explosive rock-breaking methods, a directional fracturing technique utilizing a coal-based solid waste expansive agent, termed the instantaneous expansion with a single fracture (IESF), has been developed. IESF can generate high-pressure gases within 0.05–0.5 s and utilize gas pressure to achieve directional rock fragmentation. The rock-breaking mechanisms under double-borehole conditions of conventional blasting (CB), shaped charge blasting (SCB), and IESF were studied by theoretical analysis, numerical simulation, and in situ test. The gas pressure distribution within directional fractures of IESF was determined, and the crack propagation criterion between double-borehole was established. Numerical simulation results indicated that the stress distribution in CB was random. SCB exhibited tensile stress of −10.89 MPa in the inter-borehole region and −8.33 MPa on the outer-borehole region, while IESF generated −14.47 MPa and −12.62 MPa in the corresponding regions, demonstrating that stresses generated between adjacent boreholes can be superimposed in the inter-hole region. In CB, strain was concentrated along main fractures. SCB exhibited strains of 7 mm and 8 mm in the shaped charge direction, while non-shaped charge directions showed a strain of 1.5 mm. For IESF, strain in the shaped charge direction measured 6 mm, compared to 1 mm in non-shaped charge directions, resulting in superior directional fracture control. In situ test results from Donglin Coal Mine demonstrated that IESF can form superior directional rock-breaking efficacy compared to both CB and SCB, with the average crack rates of 95.5% by IESF higher than 85.0% by SCB. This technique provides a non-explosive method that realizes precise control of the direction of cracks while avoiding the high-risk and high-disturbance problems of explosives blasting.

Effects of the Shapes of Surrounded Cracks on the Failure Behavior of Rock‐Like Samples

2025-06-17

Jinwei Fu , Jiaxin Wei , Hadi Haeri +4 more | International Journal for Numerical and Analytical Methods in Geomechanics

ABSTRACT The research employed laboratory and numerical simulation methods to examine how the shapes and sizes of surrounding cracks influence the compressive breakage properties of concrete samples. The notches examined … ABSTRACT The research employed laboratory and numerical simulation methods to examine how the shapes and sizes of surrounding cracks influence the compressive breakage properties of concrete samples. The notches examined were of various shapes, including semicircle, semi‐ellipse, triangle, rectangle, square, and trapezoid, with an angle of 45° between the notch and the horizontal axis. Additionally, numerical models were created that included 15 embedded rectangular notches. The investigation focused on different notch angles (0°, 30°, 45°, 60°, and 90°) and notch lengths (3, 6, and 9 cm). A consistent displacement loading rate of 0.01 mm/s was maintained throughout the experiment. In the intact specimens tested, the measured uniaxial compressive strength was 16 MPa, while the tensile strength was found to be 1.2 MPa. Tests on different crack types revealed that both the surface area and shape significantly influenced the fracture and failure of rock mass specimens. A correlation was established between the strength of the specimens and crack propagation. As the angle of the joints decreased and the surface area of the cracks increased, tensile cracks developed, ultimately leading to the fracturing and final breakage of the specimens. The modeled specimens exhibited the lowest tensile strength at a 30‐degree inclination angle. Semicircular cracks displayed the highest tensile strength, whereas rectangular cracks had the lowest. In comparing the laboratory and numerical outcomes, the breakage patterns, failure mechanisms, and strengths of the geomaterial samples were found to be similar.

Boundary delineation and stability assessment of post-inrush water-immersed coal pillars based on integrated microseismic monitoring and field analysis

2025-06-17

Zhang Yugeng , Heng Zhang , H. Lian +4 more | Research Square (Research Square)

<title>Abstract</title> The stability of water-immersed coal pillars remains a significant challenge in coal pillar research, particularly during post-inundation recovery following water inrush incidents. Due to harsh underground conditions, direct sampling … <title>Abstract</title> The stability of water-immersed coal pillars remains a significant challenge in coal pillar research, particularly during post-inundation recovery following water inrush incidents. Due to harsh underground conditions, direct sampling and analysis are often infeasible, hindering both engineering design and operational planning. Consequently, the analysis of coal pillar inundation based on field monitoring data has become one of the few viable approaches. This study utilizes microseismic data collected from panel 1314 at the Xiaoyun Coal Mine to delineate the boundaries of water-affected coal pillars, with the results verified through numerical simulations. Notably, the analysis reveals that coal pillars near the retreat end of the panel exhibit highly complex inundation characteristics, including irregular and abrupt boundary transitions. To better understand this behavior, in-situ stress measurements and bedding separation data were integrated to identify the dominant influencing factors and to elucidate the underlying mechanisms. The findings of this study offer important insights into the spatiotemporal behavior of inundated coal pillars post-inrush, and provide critical guidance for boundary delineation, panel design, and safe mine operations.

Generalized Matsuoka–Nakai criterion considering hydrostatic pressure dependence in the brittle–ductile region

2025-06-16

Jiacun Liu , Junjie Xiao , Dongping Liu +1 more | Deep Underground Science and Engineering

Abstract A generalized Matsuoka–Nakai criterion is proposed in this study, taking the form of a polynomial function, incorporating two parameters to characterize the evolution of the failure envelope within the … Abstract A generalized Matsuoka–Nakai criterion is proposed in this study, taking the form of a polynomial function, incorporating two parameters to characterize the evolution of the failure envelope within the deviatoric plane. These two parameters exhibit an inverse correlation with both the aspect ratio and curvature. Besides, the first parameter primarily affects the curvature around the triaxial compression state, while the second parameter predominantly influences the curvature around the triaxial extension state. Three sets of strength data under true triaxial stress states were selected to evaluate the generalized strength criterion. These sets include three types: hydrostatic pressure independent within the brittle region (HPI‐B), hydrostatic pressure dependent within the brittle region (HPD‐B), and hydrostatic pressure dependent within the brittle–ductile region (HPD‐BD). In the case of HPI, the failure envelope within the deviatoric plane remains constant and is accurately described by two fixed deviatoric parameters. In contrast, for the HPD type, the shape of the failure envelope varies with hydrostatic pressure, and this variation is precisely captured using two deviatoric parameters. The experimental data are distributed around the edges of the three‐dimensional failure envelope. Additionally, a comparison with existing criteria further validates the accuracy of the proposed criterion.