During the construction of nuclear waste storage facilities, deep drilling, and geothermal energy development, high-temperature rocks are inevitably subjected to thermal shock. The physical and mechanical behaviors of granite treated with different thermal shocks were analyzed by non-destructive (P-wave velocity test) and destructive tests (uniaxial compression test and Brazil splitting test). The results show that the P-wave velocity (VP), uniaxial compressive strength (UCS), elastic modulus (E), and tensile strength (st) of specimens all decrease with the treatment temperature. Compared with air cooling, water cooling causes greater damage to the mechanical properties of granite. Thermal shock induces thermal stress inside the rock due to inhomogeneous expansion of mineral particles and further causes the initiation and propagation of microcracks which alter the mechanical behaviors of granite. Rapid cooling aggravates the damage degree of specimens. The failure pattern gradually transforms from longitudinal fracture to shear failure with temperature. In addition, there is a good fitting relationship between P-wave velocity and mechanical parameters of granite after different temperature treatments, which indicates P-wave velocity can be used to evaluate rock damage and predict rock mechanical parameters. The research results can provide guidance for high-temperature rock engineering.
#1Wei Sun(USTB: University of Science and Technology Beijing)
#2Shunchuan Wu(Kunming University of Science and Technology)H-Index: 11
Last. Xueliang Xu(USTB: University of Science and Technology Beijing)H-Index: 1
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Abstract The thermal cracking mechanism has been increasingly investigated to analyse and solve the mechanical behaviour of rocks in deep underground engineering. Classic laboratory tests bear the intrinsic limitation of non-repeatability and lack of direct observation of the interaction effect between thermal stresses and thermal micro-cracks. In this paper, the bonded-particle model and moment tensor is used to simulate the process of thermally induced micro-and macro-cracks in Lac du Bonnet g...
#1Zhang Bo(China University of Geosciences (Wuhan))
#2Hong Tian(China University of Geosciences (Wuhan))H-Index: 13
Last. Liu Hengwei(China University of Geosciences (Wuhan))
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Abstract During drilling, reservoir fracturing and hot dry rock development, high-temperature rock is subjected to cyclic water cooling. The mechanical properties and microscopic characteristics of granite exposed to high-temperature and water-cooling cycles were investigated experimentally. The results show that the uniaxial compressive strength and elasticity modulus decrease with increasing temperature and cycles, especially above 400 °C and after 1 cycle. In addition, the P-wave velocity dec...
Abstract Knowledge of thermo-hydro-mechanical (THM) coupling process is important for rock hydrofracturing of enhanced geothermal systems (EGS). The THM coupling parameters (e.g. thermal conductivity, water permeability and Biot’s coefficient, etc) of granite undergoing treatment with heating and water cooling (HWC) were measured using laboratory tests. A large number of cracks inside the granite are caused by the uncoordinated deformation of minerals and the tensile stress induced by the treatm...
Last. Gang Mei(China University of Geosciences)H-Index: 12
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Abstract The bedrocks of deep geothermal reservoirs are exposed to cyclic water cooling during the exploitation of deep geothermal energy. Therefore, it is important to understand the physico-mechanical parameters of geothermal reservoir rocks. This paper reports on the P-wave velocity (Vp), uniaxial compressive strength (UCS) and elastic modulus (E) of granite specimens after exposure to different cyclic heating and water cooling treatments based on laboratory tests, and the relationships betwe...
Last. Xiaoguang Wang(CDUT: Chengdu University of Technology)
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Abstract In order to investigate the fracture toughness of granite samples after elevated temperature treatment and liquid nitrogen (LN2) cooling, a series of fracturing tests were performed on semi-circular bend (SCB) specimens containing pure mode-I fracture. The acoustic emission (AE) technique was employed to monitor the damage process during the test. The experimental results indicate that, overall, the fracture toughness of LN2-treated granite samples decreases with the increase of sample’...
Last. Qiang Sun(Xi'an University of Science and Technology)H-Index: 3
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Based on the research background of the damage of high-temperature jointed rock masses, this paper studies the mechanical properties of jointed granite under high-temperature conditions and analyzes the failure law of jointed rock masses with increasing temperature, decreasing temperature and types of joints. The results have important scientific and engineering value. The main research results are as follows: (1) high-temperature conditions change the mechanical properties of granite, especiall...
Numerous studies have been performed on the generation of several silicon-based engineering materials that often have used chemical materials that have high risks for health and the safety of the environment. Generally, in the synthesis of Nano-silica, tetramethoxysilane, tetraethoxysilane, and tetraethyl orthosilicate (TEOS) are used as precursor materials; however, these materials are toxic and expensive for the production of Nano-silica. This paper presents an environmentally friendly short m...
#1Zhen Yang(CUMT: China University of Mining and Technology)H-Index: 3
#2Sheng-Qi Yang(CUMT: China University of Mining and Technology)H-Index: 38
Last. Wen-Ling Tian(CUMT: China University of Mining and Technology)H-Index: 10
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Abstract This study developed a fully coupled thermo-mechanical model within the framework of ordinary state-based peridynamics to investigate the thermal-mechanical properties and fracture characteristics of granite materials under real-time temperature (RT) and post-temperature (PT) treatments. Moreover, a modified multi-layer computational method was proposed to eliminate the effect of thermal gradient-induced cracks. In this method, the size of the thermal layer was set to be larger than tha...
#1Yanjun Shen(Xi'an University of Science and Technology)H-Index: 37
#2Yuan Jiangqiang(Xi'an University of Science and Technology)H-Index: 3
Last. Ting Li(CUMT: China University of Mining and Technology)
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Granite at a high temperature can cause a decrease in strength and cracking when exposed to a rapid cooling shock. Therefore, the cooling shock method can be considered as a potential cracking technology to improve the energy exploitation efficiency. The thermal cracking damage of high-temperature granite after cooling shock induced by different low-temperature refrigerants were studied. Firstly, granite samples were heated to different targeted temperatures (i.e.100, 300, 500, and 700 °C). Then...
We summarize the feasibility of using geothermal energy from the Western Canada Sedimentary Basin (WCSB) to support communities with populations >3000 people, including those in northeastern British Columbia, southwestern part of Northwest Territories (NWT), southern Saskatchewan, and southeastern Manitoba, along with previously studied communities in Alberta. The geothermal energy potential of the WCSB is largely determined by the basin’s geometry; the sediments start at 0 m thickness adjacent ...
In a naturally saturated state, rocks are likely to be in a stress field simultaneously containing static and dynamic loads. Since rocks are more vulnerable to tensile loads, it is significant to characterize the tensile properties of naturally saturated rocks under coupled static–dynamic loads. In this study, dynamic flattened Brazilian disc (FBD) tensile tests were conducted on naturally saturated sandstone under static pre-tension using a modified split-Hopkinson pressure bar (SHPB) device. C...
