Grain size heterogeneity controls strengthening to weakening of granite over high-temperature treatment

Kang, Fangchao; Li, Yingchun; Tang, Chun’an

doi:10.1016/j.ijrmms.2021.104848

Cited by 50 publications

(9 citation statements)

References 50 publications

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“…After drying for 48 h, the physical and mechanical parameters of the rock samples were measured, as listed in Table 1. Then, the rock samples were heated to 200, 400, and 600°C at a heating rate of 5°C/min (Kang et al, 2021) separately in an MYC-5 high-temperature box-type resistance furnace. To ensure that the granite samples could be uniformly heated, they were placed in the furnace for 4 h for heat preservation after heating and then naturally cooled to room temperature in the furnace.…”

Section: Sample Preparationmentioning

confidence: 99%

Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

Qian,

Jia,

Mao

et al. 2023

Deep Underground Science and Engineering

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In order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting, dynamic Brazilian splitting tests were conducted on granite samples after thermal treatment at 25, 200, 400, and 600°C. Results show that the dynamic peak splitting strength of thermally damaged granite samples increases with increasing strain rate, showing obvious strain‐rate sensitivity. With increasing temperature, thermally induced cracks in granite transform from intergranular cracks to intragranular cracks, and to a transgranular crack network. Thermally induced damages reduce the dynamic peak splitting strength and the maximum absorbed energy while increasing the peak radial strain. The fracture mode of the thermally damaged granite under dynamic loads is mode II splitting failure. By using the axial roughness index , the distribution ranges of the wedge‐shaped failure zones and the tensile failure zones in the fracture surfaces under dynamic Brazilian splitting can be effectively identified. The radial roughness index is sensitive to the strain rate and temperature. It shows a linear correlation with the peak splitting strength and the maximum absorbed energy and a linear negative correlation with the peak radial strain. can be used to quantitatively estimate the dynamic parameters based on the models proposed.

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Section: Sample Preparationmentioning

confidence: 99%

Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

Qian,

Jia,

Mao

et al. 2023

Deep Underground Science and Engineering

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“…Kong et al (2021a, b) investigated the impact of grain size or anisotropy on the physical properties and mechanical behaviors of building stones and sandstone. Kang et al (2021) analyzed the grain size effect on the strength of granite after high-temperature treatment. Carbillet et al (2021) investigated the grain size and porosity effect on the mechanical compaction of crustal analogs.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Acoustic Emission Characteristics of Weakly Cemented Sandstone With Different Grain Sizes

Liu

Zhang

et al. 2022

Front. Earth Sci.

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The weakly cemented sandstone is widely distributed in the Western Mining Area, which is mainly formed by mineral grains and cemented minerals through compaction and cementation. To study the influence of grain size on the mechanical properties and acoustic emission (AE) characteristics of weakly cemented sandstone, uniaxial compression and Brazilian splitting AE tests were carried out on four weakly cemented sandstone specimens with different grain sizes. The physical properties, mechanical behaviors, and AE characteristics of sandstone under two conditions were analyzed, and the microfailure mechanism was investigated. The results show that the P-wave velocity, density, uniaxial compressive strength (UCS), and tensile strength of weakly cemented sandstones with different grain sizes decrease with the increase of grain size. The medium sandstone and coarse sandstone exhibit ductile failure, while the siltstone and fine sandstone exhibit brittle failure under the two conditions. The distribution of AE signal strength is nearly Gaussian in the time domain. The peak frequency and upper limit of signal strength are negatively correlated with grain size, and the occurrences of lots of high-strength AE signals can be used as the precursor of sandstone failure. The damage evolution shows the trend of low-speed damage-accelerated damage-low-speed damage, and the damage increase at the peak load is negatively related to the grain size. The microfailure mechanism is the tension-shear mixed failure, which is dominated by tensile failure, with few shear failures. The proportion of shear cracks is positively correlated with the grain size under uniaxial compression, while there is no significant correlation between shear cracks and grain size under Brazilian splitting.

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“…In the development of Dry Hot Rock, enhanced geothermal system EGS has become a very promising construction technology, the construction of underground heat exchange system has always been a difficult engineering problem. (Musa and Rosalind, 2021;Cheng et al, 2021;Kang et al, 2021;Pan et al, 2021). In order to effectively solve this problem, it is necessary to deeply study the mechanical property change and fissure development law of thermal storage matrix granite under the action of temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature damage regularity of granite based on micro-inhomogeneity

Chen²,

Chen³

et al. 2022

Front. Earth Sci.

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Enhanced geothermal system (EGS) is the primary means during Dry Hot Rock development. It is necessary to build an underground heat exchange area during its construction, and the temperature of underground rock will change significantly, thus, the mechanical properties of those rocks underground will be affected. In order to judge whether the mechanical properties under temperature are related to the crystal structure of granite, we firstly used the crystalline rock heterogeneity coefficient H to describe the crystal structure of granite. Then, the discrete element software was used to construct the GBM equivalent crystalline model and the thermal temperature field coupling model. Finally, the temperature effect test was carried out to explore the law of heterogeneity coefficient H and damage and fracture development. The results show that: 1) the variation of granite heterogeneity coefficient H and temperature will lead to the decline of mechanical properties of rock samples. 2) At the same temperature, the damage value D increases with the increase of the H value. This phenomenon is more apparent when the temperature is greater than 400°C. 3) The microcracks caused by temperature change are mainly tensile. The H value increases the number of microcracks in the crystal. 4) The damage phenomenon caused by temperature change will be affected by heterogeneity. When the temperature is high, the crystal will denature, and the stress concentration caused by heterogeneity is easier to be reflected.

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Grain size heterogeneity controls strengthening to weakening of granite over high-temperature treatment

Cited by 50 publications

References 50 publications

Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

Mechanical Properties and Acoustic Emission Characteristics of Weakly Cemented Sandstone With Different Grain Sizes

Temperature damage regularity of granite based on micro-inhomogeneity

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