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The characteristics and mechanism of microwave-induced borehole fracturing of hard rock under true triaxial stress
Abstract High stress induced by excavation disturbance in deep hard rock engineering can cause rockburst accidents. Microwave-induced borehole fracturing of hard rock is a promising technique for preventing rockbursts, the principle of which is to reduce energy and stress concentration levels in rock mass through microwave heating. The characteristics and mechanism of microwave-induced borehole fracturing of hard rock under different true triaxial stresses were experimentally investigated. After microwave-induced borehole fracturing under different σ 1 and σ 2 conditions, a complex crack network dominated by tensile cracks was generated in the rock specimen, which is consistent with the results obtained by AF and RA. According to the P-wave velocity before and after the test, the degree of thermal fracture is positively linearly correlated with σ 1 and σ 2 as a whole, and has good consistency with the length and number of thermal cracks. The results show that the technique will have better applicability and higher fracturing efficiency in high-stress areas. The thermal fracture process of basalt specimens under different σ 1 and σ 2 conditions is similar, which can be divided into a silent period, quiet period, dense period, and persistent period. In addition, thermal fracture exerts a significant threshold temperature effect, and fracture rate increases rapidly when the temperature reaches 150–192 °C (average about 172 °C). The relationship between thermal fracture and stress provides guidance for parameter design.
Highlights Microwave-induced borehole fracturing of hard rock is a promising technique for preventing rockbursts. Microwave-induced borehole fracturing tests are conducted under different true triaxial stress. The characteristics and mechanism of microwave-induced borehole fracturing under different σ 1 and σ 2 conditions are investigated. Microwave-induced borehole fracturing process is investigated by AE technique.
The characteristics and mechanism of microwave-induced borehole fracturing of hard rock under true triaxial stress
Abstract High stress induced by excavation disturbance in deep hard rock engineering can cause rockburst accidents. Microwave-induced borehole fracturing of hard rock is a promising technique for preventing rockbursts, the principle of which is to reduce energy and stress concentration levels in rock mass through microwave heating. The characteristics and mechanism of microwave-induced borehole fracturing of hard rock under different true triaxial stresses were experimentally investigated. After microwave-induced borehole fracturing under different σ 1 and σ 2 conditions, a complex crack network dominated by tensile cracks was generated in the rock specimen, which is consistent with the results obtained by AF and RA. According to the P-wave velocity before and after the test, the degree of thermal fracture is positively linearly correlated with σ 1 and σ 2 as a whole, and has good consistency with the length and number of thermal cracks. The results show that the technique will have better applicability and higher fracturing efficiency in high-stress areas. The thermal fracture process of basalt specimens under different σ 1 and σ 2 conditions is similar, which can be divided into a silent period, quiet period, dense period, and persistent period. In addition, thermal fracture exerts a significant threshold temperature effect, and fracture rate increases rapidly when the temperature reaches 150–192 °C (average about 172 °C). The relationship between thermal fracture and stress provides guidance for parameter design.
Highlights Microwave-induced borehole fracturing of hard rock is a promising technique for preventing rockbursts. Microwave-induced borehole fracturing tests are conducted under different true triaxial stress. The characteristics and mechanism of microwave-induced borehole fracturing under different σ 1 and σ 2 conditions are investigated. Microwave-induced borehole fracturing process is investigated by AE technique.
The characteristics and mechanism of microwave-induced borehole fracturing of hard rock under true triaxial stress
Zhang, Jiuyu (author) / Feng, Xia-ting (author) / Yang, Chengxiang (author) / Lin, Feng (author) / Li, Shiping (author) / Tong, Tianyang (author) / Su, Xiangxin (author)
Engineering Geology ; 306
2022-06-19
Article (Journal)
Electronic Resource
English
A novel true triaxial test system for microwave-induced fracturing of hard rocks
| DOAJ | 2021
The Microwave-Induced Fracturing of Hard Rock
| Online Contents | 2019