Effect of real-time high temperature and loading rate on mode I fracture toughness of granite

Yang, Ke; Zhang, Fan; Meng, Fanyong; Hu, Dawei; Tan, Xianfeng

doi:10.1186/s40517-022-00225-3

Cited by 6 publications

(6 citation statements)

References 33 publications

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“…The Young's modulus and Poisson's ratios of granite are reported in literatures. 39,40 As shown in Figure 5, compared with the experimental data, 47 the predicted results still show high accuracy. However, the difference of the loading rates is not directly considered in the model, which can be one of the research directions in the subsequent work.…”

Section: Experimental Verification Of the Modelmentioning

confidence: 78%

Theoretical characterization of the temperature‐dependent mode I fracture toughness of rocks

Qiu,

Zhao,

Yang

et al. 2024

Fatigue Fract Eng Mat Struct

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Mode I fracture toughness, as a key index to reflect rocks' resistance to crack propagation and failure, which is significantly affected by temperature, plays an important role in accident prevention in underground engineering. In this work, a temperature‐damage‐dependent fracture surface energy model of rocks was developed first. Then, the theoretical characterization model of the temperature‐dependent mode I fracture toughness of rocks was proposed according to the relationship between the fracture surface energy and fracture toughness. All obtained experimental results are used for verification, and the predicted values are in good agreement with the experimental results. The temperature‐dependent mode I fracture toughness model of rocks established in this study not only provides a new method to predict the fracture toughness of rocks at different temperatures conveniently but also provides the theoretical basis to the research on stability analysis, monitoring, warning, and disaster control of underground rock engineering.

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Section: Experimental Verification Of the Modelmentioning

confidence: 78%

Theoretical characterization of the temperature‐dependent mode I fracture toughness of rocks

Qiu,

Zhao,

Yang

et al. 2024

Fatigue Fract Eng Mat Struct

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show abstract

“…The widths and lengths of the cracks also increase, and the damaged zones along the crack edges are more prone to initiate new cracks under the interaction of frictional forces. This also leads to the connection and propagation of some intergranular and intragranular cracks, forming distinct crack aggregation zones [46]. After 600 • C, due to the α-β phase transition of quartz at 573 • C, transgranular cracks appear abundantly on the fracture surface, with a wider distribution and deeper aggregation.…”

Section: Microcrack Evolutionmentioning

confidence: 99%

Study on the Meso-Failure Mechanism of Granite under Real-Time High Temperature by Numerical Simulation

Li,

Zhang

2024

Applied Sciences

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In the development of geothermal resources in hot dry rocks, deep underground rock masses are typically subjected to real-time high-temperature environments. High temperatures alter the physical and mechanical properties of the rocks, directly affecting the safe and efficient utilization of hot dry rock resources. Therefore, a grain-based model (GBM) of particle flow code (PFC) was constructed based on uniaxial compression tests, and the model was verified according to macroscopic mechanical parameters and damage modes, in order to carry out the simulation study of the uniaxial compression of granite and explore the meso-failure mechanism of granite under real-time high temperature. The relationships between stress–strain curves and crack derivation, the evolution of microcracks, and the characteristics of acoustic emission activity and energy changes at different temperatures were investigated in conjunction with the results of laboratory tests. The results show that crack development, acoustic emission activity, and energy evolution during uniaxial compression include four main stages: initial compression, elasticity, plastic strengthening, and post-peak damage. The failure of granite is primarily controlled by mica and feldspar. During loading, intergranular tensile cracks first emerge within the granite, followed by intragranular tensile cracks, with shear cracks appearing last. As the temperature increases, the total number of microcracks continuously rises, the frequency of acoustic emission events increases, and both dissipated energy and boundary energy gradually decrease, showing an upward trend in the energy dissipation ratio, indicating an increase in thermal damage due to high temperatures. At 400 °C, the rate of microcrack formation increases significantly, with intergranular and intragranular cracks starting to coalesce into macroscopic cracks that extend outward. In the post-peak stage, the phenomenon of multiple peaks in acoustic emission events begins to appear. At 600 °C, the rate of microcrack formation reaches its maximum, with cracks extending throughout the sample to form a network of fractures, resulting in the granite exhibiting ductile failure characteristics.

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Section: Fracture Surface Morphologymentioning

confidence: 99%

“…However, the mechanical test results still demonstrate a predominantly abrupt fracture trend, indicating that the granite is currently undergoing a brittle-to-ductile transformation stage [22,72]. Yang et al's experimental results demonstrated that as the temperature increases up to 500 °C, the fracture behavior of granite transitions towards ductile fracture [73]. Interestingly, when the upper load limit is set at 85% at 400 °C, the significant reduction in the required number of cycles results in fewer exfoliated particles, ultimately leading to minimal disparity in the microstructures of the fracture surfaces after MTB and CTB tests.…”

Section: Fracture Surface Morphologymentioning

confidence: 99%

Effect of Cyclic Loading on Mode I Fracture Toughness of Granite under Real-Time High-Temperature Conditions

Lv,

Zhang,

Zhang

et al. 2024

Applied Sciences

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Under hot dry rock development, rock formations undergo the combined challenges of cyclic loading and high temperatures, stemming from various sources such as cyclic hydraulic fracturing and mechanical excavation. Therefore, a fundamental understanding of how rocks fracture under these demanding conditions is fundamental for cyclic hydraulic fracturing technology. To this end, a series of three-point bending tests were conducted on granite samples. These tests entailed exposing the samples to cyclic loading under varying real-time high-temperature environments, ranging from 25 °C to 400 °C. Furthermore, different upper load limits (75%, 80%, 85%, and 90% of the peak load) obtained in monotonic three-point bending tests were used to explore the behavior of granite under these conditions. The analysis encompassed the study of load–displacement curves, elastic stiffness, and mode I fracture toughness under cyclic loading conditions. In addition, the microscopic features of the fracture surface were examined using a scanning electron microscope (SEM). The findings revealed notable patterns in the behavior of granite. Cumulative vertical displacement in granite increased with the growing number of cycles, especially at 25 °C, 200 °C, and 300 °C. This displacement exhibited a unique trend, initially decreasing before subsequently rising as the cycle count increased. Additionally, the critical damage threshold of granite exhibited a gradual decline as the temperature rose. As the temperature ascended from 25 °C to 200 °C, the damage threshold typically ranged between 80% and 85% of the peak load. At 300 °C, this threshold declined to approximately 75–80% of the peak load, and at 400 °C, it fell below 75% of the peak load. Within the temperature ranging from 25 °C to 300 °C, we noted a significant increase in the incidence of cracks, crystal microfracture zones, and the dislodging of mineral particles within the granite as the number of cycles increased.

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Effect of real-time high temperature and loading rate on mode I fracture toughness of granite

Cited by 6 publications

References 33 publications

Theoretical characterization of the temperature‐dependent mode I fracture toughness of rocks

Theoretical characterization of the temperature‐dependent mode I fracture toughness of rocks

Study on the Meso-Failure Mechanism of Granite under Real-Time High Temperature by Numerical Simulation

Effect of Cyclic Loading on Mode I Fracture Toughness of Granite under Real-Time High-Temperature Conditions

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