Crack Coalescence Research Articles

Study of presplit blasting under high in-situ stress

High in-situ stress generally results in difficulties in achieving crack interconnection in presplit blasting, which can further arouse challenges related to construction cost and schedule of rock engineering. In this study, the crack interpenetration in presplitting under high in-situ stresses is theoretically analysed according to the propagation and superposition of stress waves, and then the relationships between in-situ stress, hole spacing and charge diameter in presplitting are analytically established. Following, based on the theoretical results, the rock cracking and crack coalescence induced by presplitting under different in-situ stresses are numerically investigated with a two-hole planar model in LS-DYNA. The simulation results demonstrated the effectiveness of presplitting. Subsequently, to provide guidance for practical application, presplitting with multi-holes in circular tunnel excavation under high hydrostatic pressure and high anisotropic in-situ stress is numerically performed. The performances of presplitting under high in-situ stress using different methods such as changing hole spacing and adjusting charge diameter are analysed and compared. Based on the theoretical analysis and numerical findings, we suggest that drilling boreholes along the direction of the major principal stress, using less charge, and employing small and uniform hole spacing can be effective in presplitting under high in-situ stress. This study provides insights into the mechanisms of crack interpretation in presplitting and offers guidance for overcoming difficulties in controlled blasting under high in-situ stress.

Water content effects on the strain-rate-dependent dynamic response of fine-grained and coarse-grained sandstones

In deep-mining engineering, water inrush accidents induced by dynamic disturbance were often controlled by the formation of the inrush channel (mainly caused by crack coalescence). It always originated from the microcrack growth and coalescence from the mineral-grain scales and can be influenced by the loading rates. Therefore, this paper selected fine-grained (fine grain) and coarse-grained (coarse grain) sandstones and conducted the dynamic split Hopkinson pressure bar (SHPB) tests with high-speed cameras. Moreover, the microcrack evolution was identified by the optical microscopy that can observe the true microcrack generation and propagation. The results show that water content can weaken the dynamic compressive strength of sandstones and contribute to the rate dependence of strength and energy dissipation, and moreover the coarse grain samples represent a more obvious trend (ε˙ = 40–160s−1). In addition, the box dimension was introduced to calculate the fractal dimension and built the quantitative relationship between mesodamage variable and fractal dimension to identify the microcrack evolution. It can offer a new method to understand the influenced mechanism of water content on the rate dependence of mechanical response from a multi-scale analytical framework.

Probabilistic investigation into brittle fracture of functionally graded materials using phase-field method

Modelling fracture using numerical techniques based on discrete modelling is complex as it requires tracking of progressing discontinuities in field parameters. Phase-field method for fracture is based on the variational framework and represents discontinuous crack surfaces by a damage variable that diffuses onto the crack surface. This approach offers the advantage of modelling crack where multiple crack nucleation, branching and coalescence can be determined without prior knowledge of the crack path. In this work, a probabilistic approach is used to predict the crack growth response in functionally graded material media when the mechanical properties and geometric parameters are random independent variables. Numerical implementation based on the standard phase-field method is employed in a finite element framework to model crack growth in functionally graded brittle materials. Peak failure loads are estimated within acceptable limits due to dispersion in system properties. Benchmark problems are solved to demonstrate the applicability of this technique. The proposed approach is advantageous as no further intensive computations are needed after the initial evaluation of probabilistic measures for predicting dispersion in fracture propagation when material and geometric properties exhibit scatter.

The Modelling of Rock Fragmentation Mechanisms by Carbide Buttons Using the 3D Discrete Element Method

Button cutters are commonly used in hard rock drilling because the inserted carbide buttons provide exceptional wear resistance, impact resistance, and high strength in challenging geological formations. One of the most pressing issues in designing a button cutter is to study the rock breaking mechanisms of carbide buttons. In this study, the three-dimensional discrete element method (DEM) was employed to investigate the rock breaking mechanism and cutting performance of five widely used carbide buttons, i.e., spherical, saddle, wedge, conical, and parabolic buttons. The simulation results were compared with laboratory tests to reveal the rock indentation process. The crack propagation pattern, energy dissipation, and damage evolution associated with the force–penetration depth curve were investigated. Tensile damage was the primary determinant for crack propagation and coalescence. By systematically exploring the penetration index, specific energy, and crack propagation characteristics, the conical button had a high rock breaking efficiency when the penetration depth was low, and the saddle button had a high rock breaking efficiency when the penetration depth was high. The findings can provide references for the design of a button cutter.

Micro-macro damage, deterioration and cracking of heterogeneous composite rock masses with non-penetrating cracks under uniaxial compression

Rock masses with non-penetrating cracks are widely found in nature. Their mechanical behavior plays a key role in rock engineering applications. However, previous studies have concentrated on the single lithologic layer, and few studies have reported the crack coalescence mechanism in heterogeneous composite rock mass with non-penetrating cracks (HCRC). In this study, uniaxial compression tests were performed on HCRC by discrete element numerical simulation experiments. Through the uniaxial compression simulation tests, the stress–strain variation and acoustic emission (AE) characteristics of HCRC are revealed. The instability and failure characteristics, energy evolution law and crack coalescence process of HCRC are also studied. And the influence of the crack numbers and crack positions (in weak body or strong body) on the mechanical behavior and failure processes in heterogeneous composite rock mass is investigated. The results show that the mechanical properties of HCRC are not all weakened with the increase of the crack numbers. As the number of cracks increases, the failure modes of the HCRC changes from brittle failure to ductile failure. The number of cracks will regulate the relative relationship between the strength of the two bodies of heterogeneous composite rock masses, so the crack coalescence forms, instability forms and failure characteristics of the HCRC will also change accordingly. If the number of cracks in the weak body is large, the damage of the HCRC mainly occurs in the weak body. The strong body produces a rebound energy release to the weak body, accelerating the destruction of the weak body. At this time, the overall strength of the HCRC is low. Conversely, increasing the number of cracks in a strong body will weaken the strength of the strong body. At this time, the strength difference between the strong body and the weak body decreases. The HCRC shows that the overall bearing capacity is not lower but becomes stronger. The research results provide a theoretical reference for the stability and disaster prevention of jointed rock mass engineering.

An extended peridynamic model equipped with a new bond-breakage criterion for mixed-mode fracture in rock-like materials

This paper develops a numerical model based on two-parameter extended bond-based peridynamics with a new bond-breakage criterion to simulate mixed-mode fracture in rock-like materials. This model requires only four basic parameters: Young’s modulus, Poisson’s ratio, and Mode-I and Mode-II energy release rates. Tensile and shear cracks can be distinguished explicitly from mixed-mode fracture phenomena by decomposing the bond potential into dilatational and deviatoric terms. The m- and δ-convergence studies are first performed on the gypsum specimen with a single flaw subjected to uniaxial compression. The initialization and propagation of wing cracks (tensile cracks), quasi-coplanar and oblique secondary cracks (shear cracks) are successfully captured. As an example application, the crack initiation, propagation and coalescence processes of gypsum specimens with various double-flaw configurations are investigated. Under uniaxial compression, three typical types of crack coalescence patterns characterized by shear cracking or mixed tensile-shear cracking are obtained. In all cases, the numerical results predicted by the developed approach agree well with the experimental observations, both qualitatively and quantitatively.

Numerical aspects of phase field models for low-temperature fracture in asphalt mixtures

Unlike the cohesive interface element model, the phase field model (PFM) is a newly developed computational model which provides a unified approach to predicting crack nucleation, propagation, coalescence and branching without any ad-hoc criterion. Over the years, several variants of the phase field model are presented. This paper aims to investigate the suitability of different phase field models and determine the optimal characteristic functions/model parameters for low-temperature fracture in asphalt mixtures. The analysis results of the phase field method (which belongs to a class of diffuse damage models) are also compared with the interface element model (which belongs to a class of discrete damage models). The models are compared by examining the governing equations and performing numerical simulations on single-edge notch specimens. Furthermore, various aspects of cohesive zone model (CZM) based PFM are discussed including the type of softening laws and damage growth under uniform/non-uniform stress states. It is concluded that brittle phase field models are not fully capable to predict fracture in asphalt mixtures even at low temperatures.

Coupled hydromechanical analysis of sparsely fractured crystalline rocks

This paper addresses the issue of evolution and coalescence of localized damage zones in sparsely fractured crystalline rocks. The approach incorporates a constitutive law with embedded discontinuity, which is phrased in terms of both the hydraulic and mechanical response. The formulation takes into account the hydromechanical interaction in regions intercepted by discontinuities. An internal length scale parameter is employed in the definition of equivalent hydraulic conductivity and the tangential stiffness operators, and the onset of newly developed macrocracks is detected by the bifurcation analysis. An enhanced mixed u-p finite element formulation is derived which considers the effect of progressive evolution of the fracture aperture in the weak statements of balance equations. Fully implicit temporal discretization is employed, and the finite element formulation is stabilized by invoking the Polynomial-Pressure-Projection (PPP) technique. A coupled FE analysis is conducted examining the response of Luc du Bonnet granite, with pre-existing fracture network, subjected to plane strain compression that triggers the crack propagation and coalescence. The approach is first verified on some benchmark problems that involve the presence of a dominant fracture. The results of simulations are compared with those obtained using a very fine mesh incorporating interface elements. Later, a series of coupled analyses are carried out examining the hydromechanical response in the presence of multiple fractures.

Frost damage evaluation of concrete irrigation structure by X-ray CT and AE energy release trend at the initial loading stage

Deterioration of concrete infrastructures occurs for several reasons, leading to operational problems and further collapse. Freezing-thawing processes are one of the active damage mechanisms in cold regions causing defect accumulation in the inner structure of the material and reduction of the mechanical properties. The optimal way to evaluate the damage degree is by applying non-destructive testing (NDT) methods which allow detailed and integrated results. In this research, a relationship between Acoustic Emission (AE) release energy trend and X-ray Computed Tomography (CT) parameters was investigated for damage quantification. Visualization and extraction of the internal concrete components were conducted by X-ray CT. The ultrasonic pulse velocity (UPV) and resonant frequency methods were employed for the determination of the dynamic modulus of elasticity. After utilizing AE on the compression test, the damage characterization was evaluated. The extensive description of structural members in in-service structure was acquired using principal component analysis (PCA). The X-ray CT results show that all specimens have initial damage degrees in form of cracks and voids unevenly distributed within the concrete matrix. Regarding the irrigation structure, all concrete specimens have unique particle characteristics depending on which structural members they were drilled out from. Moreover, it is observed that the accumulated damage in the form of voids positively correlates with the initial AE energy release rate. In concrete specimens with low damage degrees, the AE energy release has an upward trend of low amplitude (≤50 dB) with a silent stage at the initial loading and sudden release only near the final failure. In contrast, heavily damaged concrete shows continuous AE energy release of high amplitude (≥60 dB) and with a high initial AE energy release rate corresponding to the uninterrupted crack propagation and coalescence in the early stage of fracture and throughout the loading due to the high weak zones ratio. These results indicate that frost damage can be evaluated by the comprehensive analysis of the fracture process of concrete based on X-ray CT and AE results to characterize the damage degree.

Mechanical responses and fracturing behavior of jointed rock masses with a cavity under different dynamic loads

Dynamic impact tests were conducted on parallel-jointed granite specimens with a cavity to study the effects of joint angle and impact pressure on the mechanical responses, energy evolution characteristics, and fracturing behavior of the specimens. An improved split Hopkinson pressure bar device and a high-speed camera were employed in the experiments. The experimental results indicate that the joint angle and impact pressure have a remarkable influence on the dynamic mechanical parameters. The dynamic compressive strength and elastic modulus exhibit a nonlinear trend of first decreasing and then increasing with increasing joint angle, reaching minimum values at 45°. As the impact pressure increases, the dynamic compressive strength increases, and the elastic modulus increases or decreases, showing distinct nonlinear variation characteristics. With increasing joint angle, the transmitted energy ratio first decreases and then increases, while the reflected and absorbed energy ratios first increase and then decrease, all of which have a critical value. The reflected energy ratio of each sample is relatively small, while the transmitted and absorbed energy ratios are relatively large. With increasing impact pressure, the transmitted and absorbed energy ratios increase, while the reflected energy ratio decreases. Different joint angles and impact pressures lead to some differences in the cracking behavior and failure types of the samples, depending on the induced stress distributions in the samples under different conditions. Overall, the ultimate failure of the specimens is primarily tensile failure, accompanied by local shear failure. In addition, two distinct categories of crack coalescence patterns between the two joints and the cavity are distinguished, namely, coalescence by tensile cracks and shear + tensile cracks. There is no coalescence as a result of pure shear cracks. The influence of the impact pressure may be much greater than that of the joint angle on the type of crack.

The behavior of cutting discs for mechanized tunneling under cyclic loading conditions

In the case of a heterogenous ground condition, tunneling tools are exposed to cyclic loading. The cyclic loads can exceed the materials' permanent load-bearing capacity, which is associated with fatigue crack growth. Subsequently, the coalescence of fatigue cracks can cause spalling of material from the tool surface, leading to the deterioration of their functionality. The problem of fatigue damage on tunneling tools has lately been recognized. However, the underlying micromechanism of subcritical crack growth and the counteraction of fatigue by advanced material concepts still require fundamental research. In this work, miniaturized cutting discs made of different tool steels are subjected to a laboratory scale fatigue test and subsequently analyzed concerning fatigue damages and the material response to cyclic loading. The hot work tool steel X40CrMoV5-1, widely used for cutting discs in industrial practice, showed fatigue crack growth and significant plastic deformation of the cutting edge under cyclic loading, leading to chip formation and spalling at the cutting edge. An improvement was found by using X153CrMoV12 ledeburitic cold work tool steel, which offers a higher strength due to the coarse chromium carbides distributed in the microstructure. Due to their high young modulus, the carbides can inhibit the plastic deformation of the softer metal matrix at the cutting edge, thus increasing the edge retention and suppressing chip formation.

A time series comprehensive evaluation method of acoustic emission signal based on information entropy weighting and its application of red bed soft rock compression failure critical characteristics study

To deeply understand the self-organization critical phenomenon of red bed soft rock in the process of compression failure, a uniaxial compression test was carried out on silt mudstone. The acoustic emission signal was collected simultaneously during the whole test process. The information entropy theory was applied to weigh the acoustic emission signal. The translation time domain was introduced to analyze the acoustic emission signal time series variation law. Finally, the time series comprehensive evaluation index value variation law of acoustic emission signal based on information entropy weighting was obtained. (1) During the compression loading process, with the increase of time, all the time series comprehensive evaluation index values showed an increasing trend with the saturated cycle increasing. When the time series comprehensive evaluation index value remains stable, it could be considered that the red bed soft rock enters a critical state. (2) The acoustic emission three-dimensional positioning results showed that when the compression failure reaches the critical point, the time series comprehensive evaluation index value would be the largest, and the coalescence crack also begins to form. When entering the critical state, the time series comprehensive evaluation index value would be in a stable state. (3) When the compression failure reached the critical point, the positioning signal would accumulate towards the rupture area until the sample was destroyed. The acoustic emission three-dimensional positioning results revealed the silt mudstone internal defects evolution law. These internal defects evolve from the slow and random development-disordered state to the instantaneous development-ordered state. These evolution laws corresponded well with the time series comprehensive evaluation index value variation trend. (4) During the compressive loading process, the energy probability density function satisfied the power-function distribution under different saturated periods. The research results are expected to provide a theoretical reference for the study of red bed soft rock compression failure critical damage characteristics.

Strength Properties and Damage Evolution Mechanism of Single-Flawed Brazilian Discs: An Experimental Study and Particle Flow Simulation

Understanding the tensile strength properties and damage evolution mechanism in fissured rock is very important to fundamental research and engineering design. The effects of flaw dip angle on the tensile strength, macroscopic crack propagation and failure mode of symmetrical Brazilian discs of rock-like materials were investigated. A parallel bonding model was proposed to examine the damage of pre-flawed discs under splitting the load. The microscopic parameters of particles and bonds in the model that can characterize rock-like materials’ mechanical and deformation properties were obtained by calibrating against the laboratory test results. The crack development, energy evolution and damage characteristics of Brazil discs containing a single pre-existing flaw were studied at the microscopic scale. The results show that the flaw significantly weakens the strength of the Brazilian disc, and both the peak load and the initial cracking load decrease with increasing flaw angle. The failure modes of the rock-like specimens are mainly divided into three types: wing crack penetration damage mode, tensile-shear penetration damage mode and radial penetration failure mode. Except for the flaw dip angle 0°, the wing cracks generally sprouted at the tip of the pre-flaw, and the wing cracks at both tips of the pre-flaw are centrosymmetric. Crack coalescence was concentrated in the post-peak stage. Based on the particle flow code (PFC) energy partitions, the damage variables characterized by dissipation energy were proposed. The disc specimen’s pre-peak damage variables and peak damage variables decreased with increasing flaw angle, and the damage was concentrated in the post-peak phase.

Coalescence of Two Coplanar Internal Penny-Shaped Cracks in Brittle Solid under Uniaxial Tension Based on 3D-ILC

Crack coalescence is an important topic in the research of brittle fracture mechanics. Most of the previous studies have focused on surface or penetrating cracks, while few experimental studies have been performed on internal cracks coalescence. This study fills in the missing data. First, the 3D internal laser-engraved crack (3D-ILC) method was introduced to make internal cracks in glass without causing any damage to the surfaces of the glass. Next, uniaxial tensile tests were performed on the samples with two coplanar internal penny-shaped cracks. A new grid reconstruction algorithm is also proposed to simulate the coalescence and the growth path of two coplanar internal cracks. The crack coalescence process and fracture characteristics were analyzed in detail. The results indicate that the fracture in the test is static fracture, while the fracture is Mode I, based on the characteristics of the fracture morphology. In addition, the Wallner lines were observed after the coalescence of cracks, which were overall elliptical in shape. Before coalescence, the stress intensity factor I (KI) at the center was higher than that at the outside, indicating the attraction of the twin cracks. Then, after coalescence, the KI increased significantly at that coalescence site, which indicated that the new crack had rapidly become “elliptical” in shape following the coalescence. The normalized KII/|KImax| and KIII/|KImax| of the coplanar cracks were approximately equal to 0 in the simulation, and it was confirmed that the fracture in the test was Mode I.

Damage Mechanism on Different Joint Types of Plain Concrete under Uniaxial Compression

Excavation of tunnels or chambers causes crack initiation, propagation and coalescence, resulting in the instability and destruction of underground projects. Understanding the damage mechanism of joint rock-like materials is important for maintaining the stability of concrete construction. Based on the Mohr–Coulomb criterion and Lemaitre strain equivalence hypothesis, the coupling-damage constitutive model of rock masses was improved for application to plain concrete. Parameters including the mesoscopic and macro-meso coupling damage variables, as well as the fractal dimension, were calculated to realize the non-linear mechanical behaviour during damage evolution. The rationality of the model was verified by comparing experimental and theoretical parameters. Results revealed that the coupled-damage constitutive model of rock masses has a good applicability to plain concrete. Furthermore, two main factors affected the damage deformation: the number of joints and the inclination angle. As the number of joints increased, the early damage accumulation increased and the inflection point of the damage rate occurred in advance. The damage deformation varied significantly when the inclination angle was changed. The cumulative damage curve of the plain-concrete specimens is shown as the evolution law of an S-type curve. Both peak strength and elastic modulus were positively correlated with the damage variable. Moreover, a smaller peak strength resulted in a larger fractal dimension and coupling-damage variable. KEYWORDS: Rock mass, Joint inclination angle, Mesoscopic, Macroscopic, Fractal dimension, Coupling-damage constitutive model.

On the fracture and energy characteristics of granite containing circular cavity under variable frequency-amplitude fatigue loads

The cavities left after engineering construction obviously affect the stability of underground rock mass. Extensive studies have been devoted to investigate the mechanical behaviors of cavity-contained rock under static or impact stress paths, however, the damage process and energy dissipation characteristics were not well understood. The presented studies aim to reveal the volumetric deformation and energy dissipation characteristics of granite samples with different cavity orientations under unconventional cyclic loading conditions. The applied stress path is characterized with variable frequency-amplitude sinusoidal loads. Testing results show that the intersection between the maximum principal stress and cavity orientation affects the strength, deformation, energy, and failure modes. Crack damage evolution and hole collapse were revealed using strain rate and energy rate. It is found that the dissipated energy rate gives an early instability warning than the volumetric strain rate.A series of CT images of the failed rock give new insights into the mesoscopic mechanism of hole spalling and crack coalescence. A transition from tensile failure to shear failure was found as the cavity orientation increases with respect to the principal stress.

Experimental study on the influence of loading rate on the directional propagation law of rock mode-I cracks

To investigate the influence of the loading rate on the propagation behavior of rock mode-I cracks, a simple device for simulating rock-crack directional propagation was developed. Subsequently, loading tests were performed for rock mode-I crack propagation at different loading rates. The entire crack propagation process was monitored by applying acoustic emission (AE) and digital image correlation (DIC), and the influence of the loading rate on the mode-I crack propagation mechanism was investigated. The results showed that the peak load increased as the loading rate increased; however, the crack initiation angle and crack initiation time both tended to decrease. According to the evolution law of the deformation field, the crack propagation process can be divided into four stages: local strain band initiation, local strain band development, main control crack initiation, and main control crack coalescence. The deformation separation degree of the main control crack increased with an increase in the loading rate. The evolution process of AE can be divided into four stages: quiet, slowly increasing, booming, and decreasing periods. When the loading rate increased, the intensity of the released AE energy increased. The energy evolution law of the crack propagation process was closely related to the loading rate. The energy dissipated before the peak load decreased with an increasing loading rate, whereas the releasable elastic energy increased after the peak load increased. Scanning electron microscopy analysis revealed that when the loading rate increased, the crack propagation changed from a low-energy-efficiency fracture mode with high energy consumption to a high-energy-efficiency fracture mode with low energy consumption.

Modeling progressive failure and crack evolution in a randomly distributed fiber system via a coupled phase-field cohesive model

Despite the high microstructural heterogeneity of fiber-reinforced composites, few modeling framework provides a comprehensive and detailed understanding of the failure mechanisms of these materials. The aim of this work is to present a coupled phase-field cohesive-modeling framework that can precisely capture the progressive failure and damage behaviors of multiphasic microstructures and multifiber systems. Here, the phase-field method captures crack evolution in the matrix, and a coupled cohesive-zone model is introduced to characterize interfacial debonding. The novel model framework comprises the following novel aspects. (1) A newly developed scalar indicator that directly extracts inelastic strain from the total strain field and couples the cohesive traction-separation law with the phase-field model to determine the regularized interfacial displacement jump. (2) The periodic boundary conditions in the coupled phase-field cohesive framework are incorporated to characterize crack evolution in random fiber systems. (3) A complete set of failure modes, namely crack initiation, propagation, kinking, and coalescence are characterized in highly heterogeneous solids. Parametric studies of the novel framework yield numerical results that are highly consistent with experimental findings and reveal the effects of fiber distributions, fiber volume fractions, and boundary conditions on the nonlinear mechanical behaviors of fiber-reinforced composites. The results demonstrate the excellent potential of the novel numerical framework to evaluate the mechanical performances of composite materials in engineering applications.

Study on mechanical and fracture characteristics of rock-like specimens with rough non-persistent joints by YADE DEM simulation

Rough non-persistent joints exist widely in natural rock mass. The roughness of joints influences its mechanical and fracture characteristics. However, the research on rough non-persistent jointed rock mass is inadequate. To investigate the effects of joint angle, rock bridge angle and roughness of rough non-persistent joints, the rough non-persistent joints were truncated and their JRC was calibrated based on the Barton typical roughness profiles. A series of DEM numerical uniaxial compression tests were conducted based on the laboratory tests of rock-like specimens with 3D printed non-persistent joints. By the investigation of mechanical behaviour, crack coalescence types, crack evolution law, fracture modes presented by the strain field, and micro-fracture mechanism revealed by the displacement vectors, it was verified that YADE is suitable to simulate the fracture of rough non-persistent jointed specimens; the six types of coalescence of rough non-persistent joints were concluded, and the relation between micro-crack and macro-fracture was established by the four types of micro-cracks causing macro-fractures.

Evaluating the Effect of Overburden Depth, Mining Height, and Support Density on Coal Rib Damage Using DEM Modeling

There has been a global effort in the past decade, especially in major coal-producing countries, toward understanding the mechanics involved in the stability of coal mine ribs. Buckling and spalling of mine ribs are known to have an impact on their stability and degradation. The generation, propagation, and coalescence of cracks in mine pillar ribs are significantly affected by the overburden depths. In addition, the in situ stress magnitudes tend to affect the rib damage process. High horizontal stresses and increased depths can lead to unfavorable stress conditions, inducing coal mass damage and strength loss. Understanding the dynamics involved in rib behavior will inform better rib control practices. This study intended to assess the effect of mining depth, mining height, and supports on coal mine rib stability. In this research, the response of the coal mass was studied using distinct element modeling to better understand the failure process of coal mine ribs. The study confirmed mining depth as a significant factor controlling the rib loading and failure mechanism. In addition, increased mining heights increased the rib deformation and failure process. The evaluated support effect revealed that at shallower depths, shorter bolt lengths are sufficient to control rib stability. Increasing the bolt length for depths greater than 250 m is in order, but higher depths do not correlate with longer supports. The approach used in this study demonstrated its capacity to be used in designing rib support requirements and understanding coal mass and support mechanisms.