Influence of Thermal Treatment on the Thermal Conductivity of Beishan Granite

Zhao, Xingguang; Zhao, Zhihong; Zhang, Guo; Cai, Ming; Li, X.; Li, P. F.; Chen, L.; Wang, J.

doi:10.1007/s00603-018-1479-0

Cited by 52 publications

(15 citation statements)

References 60 publications

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“…(3) Because of various thermal expansion coe cients of mineral composition in rock, induced thermal stress between crystal and ssure leads to aw and exfoliation of rock after heat treatment [32,33]. After 400°C, the ssures between the crystalline grains in the interior of rocks shows a cracking phenomenon, and the crack cannot be recovered [38,39]. 13.2 mm, 16 mm, 19 mm, 26.5 mm, 31.5 mm, and 37.5 mm, and the typical grading curves are illustrated in Figure 12.…”

Section: Variation In Damage Using Damage Mechanics Methods To Studymentioning

confidence: 99%

Effect of Hydrothermal Coupling on Physical and Dynamic Mechanical Properties of Sandstone

Zhang

Yuan

2019

Advances in Civil Engineering

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Split-Hopkinson pressure bar (SHPB) tests were conducted for sandstone after recurrent heat-cool (H-C) cycles. Physical and mechanical properties, damage, and fracture characteristics of sandstone after the H-C cycle were explored. Additionally, the damage variable and release rate of damage strain were defined to describe the damage degree of the sandstone specimen after recurrent H-C cycles. Finally, the relationship between mass fractal dimension of fragmentation and cycling number was discussed. Results show that the P-wave velocity and density decrease with the increase of cycling number, while the porosity increases. It was found that the dynamic compressive strength and relative elastic modulus decrease with the increase of cycling number. 20 cycles is the critical point for the low temperature (L-T) group and moderate temperature (M-T) group, while it is 4 cycles for the high temperature (H-T) group. With the increase of cycling number, both the damage variable and release rate of damage strain of rock increase, while the destruction degree of sandstone becomes greater, and the corresponding fragments show more evenly.

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Section: Variation In Damage Using Damage Mechanics Methods To Studymentioning

confidence: 99%

Effect of Hydrothermal Coupling on Physical and Dynamic Mechanical Properties of Sandstone

Zhang

Yuan

2019

Advances in Civil Engineering

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“…Indeed, it has been observed that the two parameters, temperature and elastic wave velocity, are inversely correlated and induced microstructural damage affects all elastic properties [Hadley, 1976]. Other studies regarding granite subjected to thermal stresses focus on the variation of physical properties, particularly the porosity [David et al, 1999;Chen et al, 2017] and/or thermal properties such as thermal conductivity [Dwivedi et al, 2008;Kant et al, 2017;Zhao et al, 2018]. Those showed that the thermal conductivity of a cracked granite tends to decrease as temperature increases and thermally induced cracking occurs.…”

Section: Introductionmentioning

confidence: 99%

Multi-geophysical Approach for the Characterization of Thermally-Induced Cracks in Granite: Discussion of Reproducibility and Persistence

Boussaid

Mallet

Beck

et al. 2020

Pure Appl. Geophys.

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We study damage induced by low temperature variations in granite samples given their role in shallow geological reservoirs. We consider two thermal treatments, slow cooling and thermal shock, and implement a multi-geophysical approach to characterize the induced micro-scale damage. The methodology consists in monitoring elastic wave velocity and thermal conductivity as well as describing the damage by the way of Hg-porosity measurements and microscopic observations. To discuss the reproducibility of the induced damage, the same thermal protocol is performed on five samples. Our first results indicate that the thermal shock leads to a more pronounced damage. This is interpreted to be due to a larger variety of nucleated intragranular and intergranular cracks as observed by SEM and optic microscope. Yet, this more significant damage does not appear reproducible from one sample to another compared to the damage introduced by slow cooling. According to this first result, thereby, we propose a timely monitoring of elastic wave velocity, conductivity and Hg-porosity. It appears that the damage introduced by the slow cooling, unlike the thermal shock, does not present a long persistence. Indeed, after 15 days, the different properties had returned to their initial state. A time-dependence mechanism is proposed to discuss this observed process.

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“…An appropriate modelling on the mechanical behavior of granite is of great importance for site selection and design of the repository [9][10][11][12][13]. Specially, it should be noted that the heat induced by the nuclear waste may have considerable influences on the mechanical behavior of the host rock, so the thermal effect cannot be ignored [8,12,[14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…What is the relationship between the mobilized Hoek-Brown strength parameters and the rock damage or plastic strain? This has not been investigated in the published researches, and it is required to conduct a detailed study.In the recent several decades, extensive field and laboratory researches have been carried out in the site selection of HLW disposal in China [1,2,4,10,15,20,22,44,45]. Alxa candidate area in Inner Mongolia is one of the three candidate areas with large volume of granitic rock.…”

mentioning

confidence: 99%

Mobilized Mohr-Coulomb and Hoek-Brown Strength Parameters during Failure of Granite in Alxa Area in China for High-Level Radioactive Waste Disposal

Cheng

Zheng

2019

Energies

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Strength parameters of the host rock is of paramount importance for modelling the behaviors of underground disposal repository of high-level radioactive waste (HLW). Mobilization of strength parameters should be studied for a better understanding and modelling on the mechanical behaviors of the surrounding rock, considering the effect of temperature induced by the nuclear waste. The granite samples cored from NRG01 borehole in Alxa candidate area in China for HLW disposal are treated by different temperatures (T = 20 °C, 100 °C and 200 °C), and then are used to carry out a series of uniaxial and tri-axial compression experiments under various confining pressures (σ3 = 0, 5, 10, 20, and 30 MPa) in this study. With the recorded axial stress—axial strain and axial stress—lateral strain curves, mobilization of both Mohr-Coulomb and Hoek-Brown strength parameters are analyzed with the increasing plastic shear strain. It has been found that NRG01 granite samples show generally similar cohesion weakening and friction strengthening behaviors, as well as the non-simultaneous mobilization of Hoek-Brown strength parameters (mb and s), under the effect of various treatment temperatures. Furthermore, the samples treated by higher temperatures show lower initial values of cohesion, but their initial friction angle and mb values are relatively higher. This should be mainly owing to the thermally induced cracks in the samples. This study should be helpful for a better modelling on the mechanical behaviors of NRG01 granite samples as the host rock of a possible HLW disposal repository.

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Influence of Thermal Treatment on the Thermal Conductivity of Beishan Granite

Cited by 52 publications

References 60 publications

Effect of Hydrothermal Coupling on Physical and Dynamic Mechanical Properties of Sandstone

Effect of Hydrothermal Coupling on Physical and Dynamic Mechanical Properties of Sandstone

Multi-geophysical Approach for the Characterization of Thermally-Induced Cracks in Granite: Discussion of Reproducibility and Persistence

Mobilized Mohr-Coulomb and Hoek-Brown Strength Parameters during Failure of Granite in Alxa Area in China for High-Level Radioactive Waste Disposal

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