Physical Parameters, Tensile and Compressive Strength of Dolomite Rock Samples: Influence of Grain Size

Lakirouhani, Ali; Asemi, Farhad; Zohdi, Afshin; Medzvieckas, Jurgis; Kliukas, Romualdas

doi:10.3846/jcem.2020.13810

Cited by 20 publications

(10 citation statements)

References 36 publications

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“…For instance, between temperatures of 25 a 400 °C (Figure 9a-c), both the load and the duration of acoustic emissions remained belo 275 s. It was only at a temperature of 600 °C that the samples experienced failure at a proximately 270 s, with the peak displacement being more than double that at other te peratures. This is primarily due to a series of activities in the granite, such as therm expansion, dehydration, thermal decomposition, and phase transformation at 600 °C, w the most representative being the phase transition of α-quartz to β-quartz at 573 [14,63,64]. These activities disrupt the rock's native framework, increase the spacing b tween mineral grains, and promote the development of secondary defects, thereby redu ing the brittleness and increasing the ductility of the samples.…”

Section: Brazilian Test Mechanics and Acoustic Emission Patternsmentioning

confidence: 99%

Digital Fracture Surface Morphology and Statistical Characteristics of Granite Brazilian Tests after Non-Steady-State Thermal Disturbance

Chen,

Yin

2024

Mathematics

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With the widespread advent of digital technologies, traditional perspectives in rock mechanics research are poised for further expansion. This paper presents a Brazilian test conducted on granite after non-steady-state thermal disturbance at 25 °C, 200 °C, 400 °C, and 600 °C, with detailed documentation of the damage process and failure response using an acoustic emission (AE) apparatus and a digital image correlation (DIC) system. Subsequently, utilizing point cloud data captured by a three-dimensional (3D) laser scanning system, a digital reconstruction of the failed specimen’s fracture surface was accomplished. The 3D fractal characteristics and roughness response of the digitized fracture surface were studied using the box-counting method and least squares approach. Furthermore, texture information of the digitized fracture surface was calculated using the Gray Level Co-occurrence Matrix (GLCM), and statistical characteristics describing the elevation distribution were analyzed. The results elucidate the influence of thermal disturbance temperature on the mechanical parameters of the specimen, acoustic emission behavior, surface strain field evolution, and digital fracture morphology characteristics. The findings indicate a non-linear degradation effect of temperature on the specimen’s tensile strength, with a reduction reaching 80.95% at 600 °C, where acoustic emission activity also peaked. The rising thermal disturbance temperature inhibited the crack initiation load at the specimen’s center but expanded the high-strain concentration areas and the growth rate of horizontal displacement. Additionally, varying degrees of linear or non-linear relationships were discovered between thermal disturbance temperature and the 3D fractal dimension of the fracture surface, average roughness (Ra), peak roughness (Rz), and root mean square roughness (Rq), confirming the potential of Rsm in predicting the 3D fractal dimension of Brazilian test fracture surfaces. The study of the GLCM of the digitized 3D fracture surface demonstrated a high dependency of its four second-order statistical measures on thermal disturbance temperature. Finally, the statistical parameters of the fracture surface’s elevation values showed a significant non-linear relationship with thermal disturbance temperature, with a critical temperature point likely existing between 400 and 600 °C that could precipitate a sudden change in the fracture surface’s elevation characteristics.

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Section: Brazilian Test Mechanics and Acoustic Emission Patternsmentioning

confidence: 99%

Digital Fracture Surface Morphology and Statistical Characteristics of Granite Brazilian Tests after Non-Steady-State Thermal Disturbance

Chen,

Yin

2024

Mathematics

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“…Many microscale factors affect the macroscopic mechanical properties of rocks. Lakirouhani et al [6,7] conducted uniaxial compression and Brazilian splitting tests on rocks, and they found that the macroscopic strength and Young's modulus of rocks exhibit a positive correlation with their grain size and a negative correlation with their quartz mineral content. With advancements in nondestructive testing technology, it has become feasible to study rock damage evolution from a microscopic structural perspective [8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Confining Pressure on the Macro- and Microscopic Mechanisms of Diorite under Triaxial Unloading Conditions

Duan,

Yang,

2024

Buildings

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In this study, the response mechanism between macro- and microscales of deep hard-rock diorite is investigated under loading and unloading conditions. Moreover, the statistical theory is combined with particle flow code simulations to establish a correlation between unloading rates observed in laboratory experiments and numerical simulations. Subsequent numerical tests under varying confining pressures are conducted to examine the macroscopic mechanical properties and the evolution of particle velocity, displacement, contact force chain failures, and microcracks in both axial and radial directions of the numerical rock samples during the loading and unloading phases. The findings indicate that the confining pressure strength curve displays an instantaneous fluctuation response during unloading, which intensifies with higher initial confining pressures. This suggests that rock sample damage progresses in multiple stages of expansion and penetration. The study also reveals that with increased initial confining pressure, there is a decrease in particle velocity along the unloading direction and an increase in particle displacement and the number of contact force chain failures, indicating more severe radial expansion of the rock sample. Furthermore, microcracks predominantly accumulate near the unloading surface, and their total number escalates with rising confining pressure, suggesting that higher confining pressures promote the development and expansion of internal microcracks.

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“…Yu [22] found that grain size resulted in different stress concentrations within a rock; the bigger the grain size was, the stronger the stress concentration was, and the lower the rock strength was. Lakirouhani [23] concluded that there was a significant positive correlation between grain size and tensile strength.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Tensile Strength Difference with Variable Gravel Sizes on the Hydraulic Fracture Propagation in the Conglomerate Reservoir

Chen¹

2022

Geofluids

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Conglomerate reservoir is a representative reservoir of unconventional oil and gas resources, and hydraulic fracturing is also used to increase its production. However, the tensile strength of conglomerates with different sizes is various, which has an important impact on the hydraulic fracture propagation in the conglomerate reservoir. To study the tensile strength difference caused by the size of conglomerate gravel, some Brazilian splitting tests were conducted. To find the influence of tensile strength difference on the hydraulic fracture propagation, some true triaxial hydraulic fracturing experiments for layered formations were carried out. The concept of the fracture element in conglomerate formations was proposed. The results showed the following: (i) the tensile strength of conglomerate rock decreased with the increase of the gravel size, and the average tensile strengths of specimens with gravel diameters of 2.0–6.0 mm and 6.0–20.0 mm were 65.5% and 43.6% of that with 0.1–2.0 mm diameter, respectively; (ii) hydraulic fractures easily deflected at the interface of fine-grained conglomerate and medium-grained conglomerate; (iii) hydraulic fractures were prone to propagate to the layers with larger gravel sizes, and the smaller the gravel size, the lower the penetration probability. It is helpful to increase the understanding of the hydraulic fracture propagation under different gravel sizes in the conglomerate reservoir, and it can provide a reference for well distribution and hydraulic fracturing design.

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Physical Parameters, Tensile and Compressive Strength of Dolomite Rock Samples: Influence of Grain Size

Cited by 20 publications

References 36 publications

Digital Fracture Surface Morphology and Statistical Characteristics of Granite Brazilian Tests after Non-Steady-State Thermal Disturbance

Digital Fracture Surface Morphology and Statistical Characteristics of Granite Brazilian Tests after Non-Steady-State Thermal Disturbance

Effect of Confining Pressure on the Macro- and Microscopic Mechanisms of Diorite under Triaxial Unloading Conditions

The Influence of Tensile Strength Difference with Variable Gravel Sizes on the Hydraulic Fracture Propagation in the Conglomerate Reservoir

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