Abstract Microwave assisted mechanical rock breaking is a hybrid rock breaking method that combines microwave heating and mechanical rock breaking technologies and is proven to have potential applications in mineral processing, mining, and geotechnical engineering. It is, thus, important to understand the effect of microwave-induced damage on rock fracture characteristics. In this study, granite specimens of the Cracked Straight Through Brazilian Disc (CSTBD) were used to carry out the mode I fracture test of the samples irradiated by microwave for different time and thermal cycles. The results showed that the heating rate of the surface temperature of granite is about 1 °C/s, under microwave power of 0.9 kW. When the heating time exceeds the 60 s and after 3 cycles, the fracture toughness of the granite hardly changes with the heating time and cycles. Before 100 °C, the fracture toughness and fracture energy of granite decrease by about 40% with the increase of temperature. Under microwave irradiation, the medium absorber (biotite) in granite is heated and expanded, which results in thermal damage to the rock. Moreover, the polar materials in fluid inclusions move more violently than under conventional heat conduction heating, resulting in a lower decrepitation temperature of the inclusions than under conventional heating and decrepitation degree is more severe, which further leads to an increase in the density of microcracks in mineral crystal and a significant decrease in fracture toughness. When the surface temperature is 300 °C, the bending degree of the crack increases and deviates from the straight line obviously.
#1Chao Sun(CUMT: China University of Mining and Technology)H-Index: 1
#2Weiqun Liu(CUMT: China University of Mining and Technology)H-Index: 3
Last. Tianran Ma(CUMT: China University of Mining and Technology)H-Index: 3
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Abstract Microwave stimulation technology is a potential effective method to improve shale gas recovery. It is very important to study the influence factors of microwave heating and evaluate the effect of microwave heating on promoting shale microstructure development. Infrared thermal imaging technology was used to study the influence of shale permittivity, saturation and microwave irradiation (MI) parameters on shale heating. The results show that the larger the permittivity is, the faster the...
#1J. L. Jayanthi(Centre for Earth Science Studies)H-Index: 3
Last. V. Nandakumar(Centre for Earth Science Studies)H-Index: 7
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Abstract Hydrocarbon bearing fluid inclusions (HCFIs) along with the coeval aqueous inclusions could be utilized in petroleum exploration industry for determining the paleotemperature and American Petroleum Institute’s (API) gravity of oils in a basin. These parameters can indirectly yield a quick assessment on the hydrocarbon quality in a basin. Here we use fluid inclusion data as a tool to study the paleo temperature and hydrocarbon quality of two offshore basins in India (dry wells from a pro...
#1Zhen Huang(Jiangxi University of Science and Technology)H-Index: 5
#2Wei Zeng(Jiangxi University of Science and Technology)H-Index: 5
Last. Kui Zhao(Jiangxi University of Science and Technology)H-Index: 6
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Recent infrastructure development in China and other developing countries has attracted global attention. As a control project of traffic engineering, tunnels also have rapidly increased. However, fire accidents induced by traffic accident or gas explosion frequently occur in tunnels, causing irreversible damage to the tunnel rocks. Moreover, the corrosive effects of acid rain or polluted groundwater have a long-term effect on the tunnel and surrounding rocks. In this paper, physical and thermop...
Abstract For urgent solutions to existing major engineering problems such as deep mining and deep burial of high level radioactive nuclear wastes, exploring the mechanical behaviors of rocks under the synergistic effect of the burial depth of rocks and temperature is of great significance. The mode-I fracture characteristics of granite specimens in the semi-circular bending (SCB) test under the effects of different temperatures and burial depths were experimental investigated. The test results s...
Last. Wenyuan Gao(NU: Northeastern University)H-Index: 1
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Abstract Microwave-induced rock fracturing technology is considered as a promising method for rock fragmentation and mineral processing. However, owing to microwaves causing selective heating, different types of rocks show different heating effects. Some rocks are cracked and broken, some other rocks are molten, while some parts undergo no significant change. Based on microwave heating experiments on multiple types of rocks, three typical rocks with different heating effects were investigated. A...
Last. Bingqiang Wu(CSU: Central South University)H-Index: 2
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Abstract The destruction and fracture failure of heat-treated rock structures have been major issues in the underground engineering, such as disposal of highly radioactive nuclear waste, deep mining and exploitation of geothermal resources. Although several literatures have focused on studying the mode I fracture toughness and mode I fracture characteristics of heat-treated rocks, studies of the thermal effect on the mixed-mode fracture toughness and mixed-mode fracture characteristics are rare....
Abstract Cutting hard rocks has some problems such as low penetration rate and high wear rate of cutting tools. These problems can be solved by the microwave treatment of hard rocks during cutting. In this study, the effects of microwave treatment were investigated on the strength of nine different igneous rocks. First, the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests were carried out on the untreated samples. Then, the strength tests were performed on the micro...
#1Xing Li(U of T: University of Toronto)H-Index: 7
#1Xing Li(U of T: University of Toronto)H-Index: 4
Last. Gaoming Lu(NU: Northeastern University)H-Index: 1
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Abstract Microwave irradiation has been considered as one of the most promising approaches to assisting mechanical rock breakage in rock engineering. Understanding the influence of microwave-induced damage on rock dynamic fracture properties is thus desirable. Using the notched semi-circular bend (NSCB) method, dynamic fracture tests were carried out on rock specimens irradiated by microwaves with different durations. Prior to the dynamic tests, X-ray micro-CT scanning and P-wave velocity measur...
#1Gao-Ming Lu(CAS: Chinese Academy of Sciences)H-Index: 4
Last. Xiwei Zhang(NU: Northeastern University)H-Index: 14
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Microwave energy can be used to assist mechanical rock breakage for civil and mining engineering operations. To assess the industrial applicability of this technology, microwave heating of basalt specimens in a multi-mode cavity (a microwave chamber) at different power levels was followed by conventional mechanical strength and fragmentation effect tests in the laboratory. X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectroscopy were used to determine the mineral c...
During the underground coal gasification process, a large amount of heat will be released, causing the surrounding rock in the goaf to undergo a high-temperature baking process. Therefore, it is essential to study the pyrolysis characteristics and mechanism of rocks. In this paper, the red sandstone in Linyi city of China is taken as an example. According to the results of thermogravimetric analysis in argon and air, the thermokinetic parameters are calculated by non isothermal pyrolysis kinetic...
Abstract null null Liquid nitrogen (LN2) ultra-low temperature fracturing technology has broad application prospects in the storage and transformation of geothermal wells. Therefore, it is of great significance to investigate the fracture toughness of granite samples after elevated temperature treatment and LN2 cooling. In this paper, the Cracked Straight Through Brazilian Disc (CSTBD) granite specimen was heat-treated at different temperatures to study the mode-I fracture toughness of granite a...
#1Zhenlong Ge(Xi'an University of Science and Technology)H-Index: 1
#2Qiang Sun(Xi'an University of Science and Technology)H-Index: 5
Last. He Zhang(Xi'an University of Science and Technology)H-Index: 2
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The mechanical properties of rock deteriorate at high temperatures, affecting the stability of the rock. Therefore, it is of great importance to predict the failure of rock at high temperatures. Through the uniaxial compression test, the acoustic emission (AE) characteristics of limestone during loading after being submitted to different heat treatment temperatures were studied, and the variation of the limestone b-value with temperature was discussed. The results show that the characteristics o...