Brazilian Splitting Test Research Articles

Study on the Compressive and Tensile Properties of Latex-Modified Cement Stone.

The integrity of wellbores is essential for the safe and efficient operation of drilling activities. Cement plays a critical role in this process, serving as a primary barrier that isolates the casing from the surrounding formation. To ensure the proper application of cement in wells, a thorough understanding of its mechanical properties is essential. Latex-modified cement stone (LMCS) offers significant advantages due to its anti-channeling, anti-corrosion, and mechanical characteristics. This study examined the mechanical properties of LMCS through uniaxial and triaxial compression and Brazilian splitting tests. Under uniaxial compression, the elastic modulus, Poisson's ratio, and compressive strength of LMCS were found to range from 4.08 to 8.29 GPa, 0.05 to 0.46, and 15.82 to 22.21 MPa, respectively. In triaxial compression tests with confining pressures of 2 MPa, 4 MPa, 6 MPa, 8 MPa, and 10 MPa, the elastic modulus ranged from 4.48 to 6.87 GPa, Poisson's ratio from 0.05 to 0.16, and compressive strength from 27.38 to 39.58 MPa. The tensile strength of LMCS ranged from 2.34 to 3.72 MPa. Moreover, the compressive strength of LMCS increased with confining pressure, showing enhanced resistance to failure due to the confining effect. However, the rate of increase gradually diminished. Strength criteria for LMCS, including Mohr-Coulomb and Drucker-Prager parameters, were derived from the triaxial compression tests. These strength criteria parameters provide a useful reference for developing the constitutive model of LMCS and for simulating triaxial compression conditions. The findings of this research offer valuable insights that can guide the construction of oil and gas wells.

Evaluation of Concrete Fatigue Damage with Elastic Wave-based Measurement Techniques

Fatigue damage is a progressive and permanent change in the internal material structure due to cyclic loading. The cyclic loads can be due to wind, waves, temperature variation, and traffic loads. Each cyclic load application introduces micro-damages that accumulate to induce failure. Detecting these micro-damages requires sensitive measuring techniques. Hence this research compares the sensitivity of different measuring techniques applied to fatigue experiments of concrete. The applied NDT are the passive acoustic emission technique (AET) and active ultrasonic measurements. In addition, linear variable differential transformers (LVDTs) are applied as a reference measurement. Accordingly in this research, cylindrical concrete samples are subjected to monotonic and cyclic Brazilian splitting tests. The cylinders are 100 mm in diameter and 150 mm in length. The cyclic load is applied to these samples with a loading frequency of 5 Hz. During the tests, the damage evolution is monitored with AET, ultrasonic measurements and LVDTs. There are eight AE sensors attached to the sample. The two LVDTs are positioned at the center of the sample's front and back side. Besides passively monitoring the acoustic emissions, the AET sensors are also used to do active ultrasonic measurements. The research reports the comparison conducted on the deformations and cracks measured with the LVDTs, the damage growth identified with the AET, and the change in the ultrasonic pulse velocity measurements. In addition, the study also presents the damage analysis capacity of the methods across different types of loading: monotonic, constant amplitude, and stepped fatigue loading. The comparison shows that combination of AET and ultrasonic velocity measurement is a sensitive indicator for damage growth.

Effects of Different Cooling Treatments on Heated Granite: Insights from the Physical and Mechanical Characteristics.

The exploration of Hot Dry Rock (HDR) geothermal energy is essential to fulfill the energy demands of the increasing population. Investigating the physical and mechanical properties of heated rock under different cooling methods has significant implications for the exploitation of HDR. In this study, ultrasonic testing, uniaxial strength compression experiments, Brazilian splitting tests, nuclear magnetic resonance (NMR), and scanning electron microscope (SEM) were conducted on heated granite after different cooling methods, including cooling in air, cooling in water, cooling in liquid nitrogen, and cycle cooling in liquid nitrogen. The results demonstrated that the density, P-wave velocity (Vp), uniaxial compressive strength (UCS), tensile strength (σt), and elastic modulus (E) of heated granite tend to decrease as the cooling rate increases. Notably, heated granite subjected to cyclic liquid nitrogen cooling exhibits a more pronounced decline in physical and mechanical properties and a higher degree of damage. Furthermore, the cooling treatments also lead to an increase in rock pore size and porosity. At a faster cooling rate, the fracture surfaces of the granite transition from smooth to rough, suggesting enhanced fracture propagation and complexity. These findings provide critical theoretical insights into optimizing stimulation performance strategies for HDR exploitation.

Improving erosion resistance of calcareous sand slope with zinc sulfate solution

Loose and uncemented calcareous sand slopes are prone to collapse under rainstorm erosion. In order to improve the erosion resistance stability of slopes, it is crucial to enhance the erosion resistance of calcareous sand. In this study, a new method of cementing calcareous sand with zinc sulfate solution (ZSS) is proposed. The ZSS reinforcement technique can effectively cement calcareous sand, enhance the mechanical properties and help reduce erosion on calcareous sand slopes. A series of laboratory experiments were conducted, including uniaxial compression tests, Brazilian splitting tests, surface penetration tests, microscopic tests, and rainfall scouring tests. The test results show that the uniaxial compressive strength of calcareous sand achieved 8.3 MPa reinforced with ZSS. Microscopic analyses revealed the mechanism of reinforcement, discovering the formation of environmentally friendly compounds such as ZnCO3 and CaSO4·2 H2O between calcareous sand particles, which enhanced the soil mechanical properties. The calcareous sand slope reinforced with ZSS forms a hard shell on the slope surface, which effectively improves the erosion resistance of the slope. After being reinforced with a ZSS concentration of 1.0 mol/L, the slope remained stable after 20 min of scouring at a rainfall intensity of 80 mm/h. This method provides a quick solution for reinforcing calcareous sand slopes and holds promising potential for practical engineering applications.

Dynamic constitutive relation and macro/micro failure mechanism of fine-grained WC-Co composite

As the core of an armour-piercing projectile, it is crucial to provide a microscopic perspective to elucidate the macroscopic mechanical responses of fine-grained WC-Co composite under dynamic loadings. This study investigated the dynamic constitutive relation and macro/micro failure mechanisms of fine-grained WC-Co composite. Results showed that the compressive and tensile strengths increase with the strain rate influenced by the inertia effect of crack propagation and the presence of the Co phase. The strain rate dependency mechanism of the composite was obtained by comparing it with typical ceramic materials. Macro-crack propagation and distribution were discussed under different stress states in dynamic compression and Brazilian splitting tests. Microscopic failure mechanisms were obtained by SEM technique, revealing that the Co phase creates numerous localized dimple fractures and improves the plastic deformation of the WC-Co composite.

Experimental study of rock fracture behavior under direct tension using three-dimensional digital image correlation

Understanding the mechanical characteristics of rocks when subjected to direct tension is crucial for assessing the stability of rock formations. Within the scope of this research, a series of tests was conducted using Tage tuff to assess the deformation behavior and crack extension of rock under direct tension. The axial, lateral, and shear strain fields as well as crack propagation, localized deformation behavior, and failure mode of the rocks were analyzed using three-dimensional digital image correlation method. The results showed that the axial strain fields on the specimen surface were heterogeneous, with different locations and localization occurring in the pre-peak stage, which was similar to the evolution of shear strain, whereas the lateral strain only showed slight changes. The crack extension direction was inferred, indicating that both tensile and shear stress occurred in the tests. Furthermore, different stress–strain responses were observed for the inside and outside of the localized bands. Then, the surface patterns of specimen failure were scanned and analyzed to assess the failure mode and residual strength of the specimen under direct tensile stress. Finally, the results of direct tension, uniaxial compression, and Brazilian split tests for Tage tuff were compared, and the complete stress–strain curve of uniaxial tension (UT) was simulated using a nonlinear-variable-compliance constitutive equation. This study provides a deeper understanding into the damage behavior of rocks under direct tension.

Experimental and numerical analysis of Brazilian splitting mechanical properties and failure mechanism for composite discs

The properties of structural planes and the strength of rock matrix significantly influence the splitting characteristics of composite rock masses. To investigate the effects of structural plane and differences in matrix strength on the mechanical behavior and failure characteristics of composite jointed rock bodies, composite jointed disc specimens with varying structural plane roughness and matrix combinations were prepared. These specimens were then subjected to Brazilian split tests under different loading angles ranging from 0° to 90°. Results indicate that the failure mode of the specimens is determined by the angle of the structural plane. As the structural plane angle increases, the failure mode transitions from structural plane failure to combination failure and finally back to structural plane failure. Increased roughness of the structural plane reduces the extent of structural plane failure, while matrix strength has no significant impact on the failure mode. The failure load of the specimens increases with increasing structural plane angle, roughness, and matrix strength. The influence of structural plane roughness and matrix strength on the mechanical properties of the specimens grows with increasing structural plane angle. Increases in structural plane roughness and matrix strength significantly enhance the strain energy and dissipated energy of the disc model. Finally, an analysis of the stress state on the structural planes is combined with an exploration of the failure mechanisms of the specimens.

A new model for chloride ion diffusion in cracked concrete with consideration of damage and strain fields

In this paper, a new model for chloride diffusion in cracked concrete is presented. The model was developed within a standard continuum damage mechanics framework but newly considers both an irreversible damage variable and a strain field, gaps identified through a literature review, offering a more comprehensive description of the diffusion-like processes in concrete with small and moderate cracks than current models. The model utilizes a realistic dependence for the diffusion coefficient on the damage state and employs a bi-logistic mapping function or an S-curve mapping function to effectively describe the non-linear effects of cracks on diffusion in concrete. The dependence on the strain field introduced by this model not only allows examination of diffusion in opening cracks, it also enables the process of crack closing to be simulated, whatever the irreversible damage variable may be. This paper also proposes a novel calibration procedure for experimental testing involving the use of the Brazilian splitting test on samples enclosed in a steel ring. This innovative approach simplifies the process of creating a portfolio of cracks with varying widths. In the calibration tests described here, samples were subjected to natural diffusion while chloride content was monitored in inlet and outlet chambers attached to the samples, eliminating the need for laborious chloride profiling. Our in-depth examination of chloride diffusion in cracked concrete is applicable to analyses of corrosion in steel-reinforced concrete structures worldwide, with the new calibration procedure offering a straightforward method for populating the model with realistic material parameters, thus providing a valuable tool for accurately predicting chloride penetration in real-world scenarios.

Enhancement of the tensile properties of cement mortar composites with nanoadditives produced by chemical vapor deposition

While graphene effectively enhances the performance of cement-based materials, its current production methods are characterized by environmental unfriendliness and high energy consumption. To investigate a large-scale and eco-friendly graphene preparation approach, Carbon Nano Sheets (CNS) were synthesized via chemical vapor deposition (CVD). The influence of CNS content on the tensile strength of cement mortar was assessed through the Brazilian splitting test. Concurrently, the mechanism of CNS was examined using acoustic emission monitoring and scanning electron microscope. The experimental results revealed that methane can be effectively decomposed into high-quality CNS at 1080 ℃ when using fly ash, silica fume, and sand as substrates. The Brazilian splitting test revealed that CNS effectively enhances the tensile strength of cement mortar, with improvements ranging from 9 % to 58.7 %. Acoustic emission results indicated that the inclusion of CNS reduces the occurrence of micro-fractures during the failure of cement mortar specimens. Furthermore, nano-mechanical testing and microstructural characterization demonstrate that CNS can reduce micro-cracks and pores in the interface transition zone and hydration products, playing a role in dense hydration products. Furthermore, it can decrease the width of the interface transition zone and enhance the micro-mechanical properties of cement pastes. This study offers a novel approach for the eco-friendly production of cement nano additives.

Investigation of the bedding effect on coal rock under Brazilian splitting tests

This contribution focuses on understanding the bedding effect of coal rocks under the Brazilian splitting test. First, multiple Brazilian splitting tests were performed on coal rocks with various bedding angles to systematically investigate the influence of stratification. Subsequently, numerical models with stratified structures were constructed, and a continuous–discontinuous numerical analysis method based on the cohesive zone model (CZM) was employed to conduct the corresponding numerical investigations. Results indicate that the load–displacement curves of coal rock specimens with different bedding angles can be classified into four stages: initial compaction stage, elastic deformation stage, crack rapid coalescence stage, and final destruction stage. With increase in the bedding angle, the failure patterns of coal rock specimens can be categorized into three groups: 1) stretching damage along bedding planes; 2) mixed tension and shear failure along the bedding planes and the coal matrix; and 3) stretching failure passing through the coal matrix. Furthermore, the tensile strength and cumulative acoustic emission (AE) energy–displacement relations are significantly influenced by the bedding angle. The numerical model can effectively predict the mechanical responses and fracture behavior of coal rock specimens, providing empirical parameters for the simulation of similar rock engineering.

Experimental Study on the Effect of Environmental Water on the Mechanical Properties and Deterioration Process of Underground Engineering Masonry Mortar

Urban underground engineering is generally buried at a shallow depth and suffers long-term environmental water effects such as rainfall, rivers, underground pipeline leakage, and groundwater. The mechanical properties of the structures are affected by constant deterioration, which seriously hinders the safe, healthy, and sustainable development of the city. On the basis of on-site investigation of civil defense engineering, this article simulates the water environment conditions of mortar in underground engineering in the laboratory and conducts manual sample preparation in the laboratory. Then, water, H2CO3, NaCl, and Na2CO3 solution or wet–dry cycles are used to corrode the sample, respectively. A uniaxial compression test, Brazilian splitting test, analyses of the acoustic emission signals and electromagnetic signals, and magnetic imaging testing are performed, respectively. The results show that an increase in the action time of environmental water leads to a gradual increase in the uniaxial compressive strength, tensile strength, and elastic modulus of cement mortar, but it will decrease over a long period of time. Different environmental water components can also lead to a different performance of soaked mortar. The uniaxial compressive strength R, tensile strength σt, and elastic modulus E of mortar samples exhibit values in different solutions in the order of H2CO3 solution < NaCl solution < Na2CO3 solution < water. A moderate solution soak time can enhance the mechanical properties of the mortar, but this effect decreases at long time scales. The effect of wet–dry cycles on the mechanical properties and degradation process of mortar is significant. With the increase in wet–dry cycles, the porosity of mortar continuously increases. The cumulative ringing count, energy, amplitude, and impact number of acoustic emission signals always increase when the samples are loaded to failure. The uniaxial compressive strength, tensile strength, and elastic modulus first increase and then decrease. The experimental results lay the foundation for further investigating the performance changes in mortar under complex water environments in underground engineering.

An interface constitutive model of plastic tensile–compressive damage under impact loading based on continuous–discontinuous framework

Bullet penetration test is a classic impact loading test, which involves complex dynamic elastic–plastic response. Conventionally, this process was often described using a single high-strain-rate constitutive model, which could only capture a specific type of failure during the impact damage process. Furthermore, these constitutive models were mostly defined on element and posed the risk of computational divergence(element distortion). In this work, a novel constitutive model for combined tensile–compressive damage in interface element was developed within a Continuous–Discontinuous Element Method(CDEM) framework. This model successfully captures the processes of pit formation and target collapse during projectile penetration. The tension and compression damage parts of the developed interface constitutive model were validated through Brazilian splitting test and interface direct shear test. Subsequently, bullet penetration test is simulated and the post-penetration velocity is compared with published results from other studies, with computational errors found to be within 2.56%, thus validating the accuracy of the developed interface constitutive model.

Study on acoustic emission and local deformation characteristics of feldspar vein-intrusive metagabbro at different angles of splitting

Feldspar vein-intrusive metagabbro is a special geological structure, and different stress angles have an important influence on the fracture mode and deformation characteristics of metagabbro. A Brazilian splitting test on feldspar vein-intrusive metagabbro was performed using three distinct stress angles (0°, 45°, and 90°), and acoustic emission signals and strain characteristics were monitored synchronously during the test. The results showed that the damage pattern of the feldspar vein-intrusive metagabbro was related to the feldspar mineral perforation damage on the main rupture surface. With the increase in stress angle, the percentage of high peak frequency increased gradually. The phenomenon of strain lagging stress appeared in the rock samples before the peak damage. The feldspar minerals played a controlling role in the expansion of microcracks in the feldspar vein-intrusive metagabbro. Significant differences in the local deformation coordination of rocks under different stress angles were observed. The deformation coordination of rock samples with a stress angle of 0° was much lower than that of other rock samples. This study is of great significance for the understanding of the deformation and damage laws of similar geological structures and also provides an important theoretical basis for the stability of deep chambers.

Experimental investigation on the influence of temperature on the fracture surface variations of granite after Brazilian splitting tests

Understanding the variation in the morphology of rock fracture surfaces after high-temperature is of great significance for evaluating the strength, deformation, and seepage characteristics of deep engineering rock masses. In this study, the variations in the granite fracture surface roughness after exposure to different temperatures (25–800 °C) were investigated, and the damage deterioration mechanism was revealed. The results showed that the maximum fluctuation (Z) and root mean square of the first derivative (Z2) of the granite fracture surface tended to increase with increasing temperature, whereas the fractal dimension (D) decreased, suggesting that the higher temperature contributed to greater roughness of the fracture surface. The anisotropy of the fracture surface was more evident at higher temperatures and had greater roughness in the 45°–75°, 105°–135°, and 155°–170° directions after different temperatures. Physicochemical reactions, such as dehydration, quartz phase transformation, and mineral oxidation, occurred in the granite owing to high temperatures. These reactions changed the crystalline state of the minerals and facilitated the increase and expansion of microcracks, thereby weakening the cementing property between mineral particles. Fracture surfaces with higher roughness were formed after tensile failure of the rock. The research results may provide theoretical references for the construction and operation of deep engineering.

Influences of bedding angle and soaking time on the mechanical behaviour of silty mudstone: laboratory testing and theoretical modelling

Silty mudstone is highly susceptible to the influence of hot and humid environments, leading to the deterioration of its mechanical properties presenting a geohazard and even resulting in geological disasters. Accurately characterizing the effects of bedding and water–rock interaction on the mechanical behaviour of silty mudstone is a crucial prerequisite for the protection and reinforcement of silty mudstone slopes. To this end, uniaxial compression tests and Brazilian splitting tests were conducted to examine the mechanical properties of bedded silty mudstone. Based on the test results, the effects of bedding angle and soaking time on mechanical properties such as tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone were revealed. The test results showed that the tensile strength increased exponentially with increasing bedding angle. The observed split failure patterns of bedded silty mudstone encompassed splitting–pulling damage, shear damage and splitting damage. The uniaxial compressive strength of silty mudstone exhibited a U-shaped variation with an increase in bedding angle. The specimen with a bedding angle of 45° had the lowest uniaxial compressive strength at 7.64 MPa. Furthermore, the elastic modulus of silty mudstone was positively correlated with the bedding angle. The failure patterns of bedded silty mudstone under uniaxial compression included splitting-tension damage, shear-slip damage and splitting-shear damage. The saturated tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone exhibited an exponential decrease with increasing soaking time. The test data confirmed the applicability of the Jaeger equation to the uniaxial compressive strength of bedded silty mudstone. Subsequently, a modified Hoek–Brown failure criterion was derived by combining fracture mechanics theory and test results and introducing a softening factor. The parameters A , D and m in the above failure criterion decreased exponentially with increasing soaking time and an empirical Hoek–Brown failure criterion considering the soaking time was established. Compared with previous theoretical models, this model is more adaptable to the actual engineering situation, which results in more accurate calculations.

Comparison of the Sample Preparation Strategies and Impacts on the Tensile Strength of Gas Shale with Variable Moisture Conditions

Moisture significantly affects the mechanical behavior of gas shale and further determines the hydraulic fracturing performance, as it is more attractive. Nevertheless, batch experiments have usually involved variable methodologies regarding the preparation of moisture-contained shale specimens in the sequence (and/or frequency) of drying and soaking treatments. Accordingly, this work investigates how the preparation methodology influences the test results of moisture-contained shale samples. This study compares three commonly used shale sample preparation strategies for acquiring different moisture contents, that is, “dry-wet”, “dry-wet-dry”, and “wet-dry-wet” strategies, followed by a Brazilian splitting test for the mechanical parameters. The results show that under the same saturation conditions, the longer the soaking time during sample preparation, the higher the degradation degree of shale tensile strength. Meanwhile, prolonged soaking can lead to a more discrete distribution of strength values, and the failure mode may deviate from the Brazilian splitting theory model. Under the combined influence of moisture content and soaking time, the tensile strength of shale decreases approximately linearly with increasing saturation, while the degradation degree increases nonlinearly with increasing saturation, and the degradation rate changes from slow to fast. According to the observation of the microstructure of hydrated shale, prolonged soaking can lead to an increase in the expansion of clay minerals in shale by hydration, resulting in looser and more fragmented internal structure, and further degradation in shale strength. In order to weaken the interference of hydration when studying the effect of moisture content on the tensile strength of shale, the soaking time should be minimized as much as possible during the preparation process.

Experimental study on the deterioration of mechanical properties of sandy mudstone under different water-gas interactions

Based on the water-rock-gas coupling test system, the work combined the scanning electron microscope and XTDIC 3D full-field strain measurement system. The Brazilian splitting test was performed on four groups of sandy mudstone specimens under contrast (CO), mash-gas soaking (MS), water-mash gas soaking (WM), and water-soaking (WS) conditions. The tensile strength, deformation failure, and microscopic characteristics of fractures were studied to reveal the deterioration mechanism of the tensile properties of sandy mudstone under water-gas coupling. The results showed that the uniaxial tensile strength of sandy mudstone specimens under the three soaking conditions was less than that of the contrast conditions. Compared with specimens in the CO group, the tensile strength of specimens in MS-WS groups was reduced; the WS group decreased the most. Specimens changed from brittle failure to plastic failure after soaking. The decrease rate in strength after the peak was consistent with the change trend in tensile strength. It led to a larger localized deformation zone of specimens and more obvious displacement. The deformation localization zone of the WS group was the broadest, with the most intense displacement. Besides, stress concentration first occurred in the submerged part of the WM group. Fractures expanded in the direction of maximum principal strain. The internal pore structure of sandy mudstone specimens in each group changed after soaking. The average porosity, maximum pore area, and probability entropy of specimens in WS-MS groups increased compared to the CO group. The WS group had the largest reduction and the MS group had the smallest. The pre-peak energy storage capacity of sandy mudstone specimens was gradually weakened. Compared with the CO group, that in the WS-MS groups was reduced. The WS group had the greatest reduction, and the MS group had the smallest. The deterioration effect of water on the interior of sandy mudstone was stronger than that of gas. The work is of great significance for understanding the stability of coal and rocks in closed-pit high-gas mines.

A new type of shale gas reservoir—carbonate-rich shale: From laboratory mechanical characterization to field stimulation strategy

Recently, a new promising type of marine shale gas reservoir, carbonate-rich shale, has been discovered. But the mechanical properties of this type of shale were still unrevealed and the corresponding reservoir stimulation design was lack of guidance. Using the deep downhole cores of an exploratory carbonate-rich shale gas well, the physical and mechanical parameters and failure mechanism of the whole reservoir section were acquired and evaluated systematically, by performing XRD, tri-axial compression, Brazilian splitting, and fracture toughness tests. A new model was established to evaluate the reservoir brittleness based on fracture morphology and stress-strain curve. Recommended strategy for reservoir stimulation was discussed. Results showed that (1) Carbonate-rich shale possessed high compressive strength and high Young's modulus, which were improved by 10.74% and 3.37% compared to that of siliceous shale. It featured high tensile strength and fracture toughness, with insignificant anisotropy. (2) With the content of carbonate minerals increasing, the shear failure morphology transformed from sparse and wide brittle fractures to diffusely distributed and subtle plastic cracks. (3) The brittleness index order was: siliceous shale, clay-rich shale, carbonate-rich shale, and limestone. (4) The special properties of carbonate-rich shale were rooted in the inherent feature of carbonate minerals (high strength, high elastic modulus, and cleavage structure), resulting in greater challenge in reservoirs stimulation. The above findings would promote the understanding of carbonate-rich shale reservoirs and provide reference for the optimum design of reservoir stimulation.

Estimating the macro strength of rock based on the determined mechanical properties of grains and grain-to-grain interfaces

Obtaining complete rock cores is exceptionally challenging in certain extreme environments, such as deep earth and deep space; consequently, it is difficult to obtain the macro strengths of rock, which are the key indexes for engineering design, via standard rock mechanical tests. This research indicates that by determining and leveraging the mechanical properties of grains and grain-to-grain interfaces, the rock macro strength can be effectively estimated. Nanoindentation tests were first conducted to determine the elastic modulus of the mineral grains and their interfaces. Subsequently, symmetrical and anti-symmetrical four-point bending tests were executed to establish the statistical law governing interfacial tensile and shear fracture toughnesses. Furthermore, by employing the Dugdale–Barenblatt model and considering the oblique angular distribution of interfacial cracks, the corresponding tensile strength, shear strength, and friction parameter were derived. These meso‑mechanical parameters were then inputted into the 3D Finite-Discrete Element Method to estimate rock macro strength. And the numerical results were then compared with the results of standard uniaxial compression, direct tension, Brazilian splitting, and direct shear tests. The consistency observed between the predictions and experimental results attests to the validity of the proposed method.

Effects of displacement rate on mechanical behaviors and failure mechanism of non-caking coal in Brazilian splitting tests

Effects of displacement rate on mechanical behaviors and failure mechanism of non-caking coal in Brazilian splitting tests