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Journal ArticleDOI

How do thermally induced microcracks alter microcracking mechanisms in Hong Kong granite

01 Oct 2021-Engineering Geology (Elsevier)-Vol. 292, pp 106268
TL;DR: In this paper, the authors analyzed the effects of pre-existing thermal microcracks on the microcracking mechanisms of Hong Kong granite under mode I loading, and found that the presence of the thermal micro-cracks aggravates the micro crack damage.
About: This article is published in Engineering Geology.The article was published on 2021-10-01. It has received 13 citations till now.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors investigate the effect of the loading condition and granite heterogeneity on the cracking mechanism and find that the microcracks under mixed-mode I-II loading do not nucleate as easily as compared with that in mode I case.

14 citations

Journal ArticleDOI
TL;DR: In this article , acoustic emission (AE) signals were acquired, and their clustering features were automatically extracted by the clustering unsupervised learning method, which showed that a class of AE signals featured high rise time, high ring count, high energy and low peak frequency and low quantity can be used as an indicative precursor feature of hard rock instability.

9 citations

Journal ArticleDOI
TL;DR: In this paper , a cracked straight-through Brazilian disc (CSTBD) specimen was applied to investigate the fracture behavior of two types of rock materials (hard rock and soft rock) under high temperature, which was made of granite and green sandstone and heating temperature from 25 °C (room temperature) to 700 °C.

9 citations

Journal ArticleDOI
TL;DR: In this article , the authors employed the Split Hopkinson pressure bar to measure the dynamic compressive mechanical response of shale specimens with five different bedding dips after thermal treatment of 25-200 °C under the same impact energy.

8 citations

Journal ArticleDOI
TL;DR: In this article , the effects of cyclic freeze-thaw (F-T) on the microcracking behavior of sandstone under mode I loading were investigated and the results showed that the damage degree does not significantly increase until the F-T cycle number exceeds a threshold between 60 and 90.

5 citations

References
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Journal ArticleDOI
01 Mar 1991-Nature
TL;DR: In this article, the failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission, and the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process.
Abstract: The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process which normally would occur violently in a fraction of a second. Using a procedure originally developed to locate earthquakes, acoustic emission arrival-time data are inverted to obtain three-dimensional locations of microseisms. These locations provide a detailed view of fracture nucleation and growth.

870 citations

Journal ArticleDOI
TL;DR: A review of the successes and limitations of acoustic emission (AE) studies as applied to the fracture process in rock with emphasis on our ability to predict rock failure is presented in this paper.

867 citations

Journal ArticleDOI
TL;DR: A review of recent work on microcracks in rock can be found in this paper, with a focus on the morphogenesis, kinematics, dynamics, population statistics and observational techniques.

812 citations

01 Dec 1993
TL;DR: A review of the successes and limitations of acoustic emission (AE) studies as applied to the fracture process in rock with emphasis on our ability to predict rock failure is presented in this paper, where application of laboratory AE studies to larger scale problems related to the understanding of earthquake processes is also discussed.
Abstract: The development of faults and shear fracture systems over a broad range of temperature and pressure and for a variety of rock types involves the growth and interaction of microcracks. Acoustic emission (AE), which is produced by rapid microcrack growth, is a ubiquitous phenomenon associated with brittle fracture and has provided a wealth of information regarding the failure process in rock. This paper reviews the successes and limitations of AE studies as applied to the fracture process in rock with emphasis on our ability to predict rock failure. Application of laboratory AE studies to larger scale problems related to the understanding of earthquake processes is also discussed. In this context, laboratory studies can be divided into the following categories. 1) Simple counting of the number of AE events prior to sample failure shows a correlation between AE rate and inelastic strain rate. Additional sorting of events by amplitude has shown that AE events obey the power law frequency-magnitude relation observed for earthquakes. These cumulative event count techniques are being used in conjunction with damage mechanics models to determine how damage accumulates during loading and to predict failure. 2) A second area of research involves the location of hypocenters of AE source events. This technique requires precise arrival time data of AE signals recorded over an array of sensors that are essentially a miniature seismic net. Analysis of the spatial and temporal variation of event hypocenters has improved our understanding of the progression of microcrack growth and clustering leading to rock failure. Recently, fracture nucleation and growth have been studied under conditions of quasi-static fault propagation by controlling stress to maintain constant AE rate. 3) A third area of study involves the analysis of full waveform data as recorded at receiver sites. One aspect of this research has been to determine fault plane solutions of AE source events from first motion data. These studies show that in addition to pure tensile and double couple events, a significant number of more complex event types occur in the period leading to fault nucleation. 4) P and S wave velocities (including spatial variations) and attenuation have been obtained by artificially generating acoustic pulses which are modified during passage through the sample. (A) This paper was presented at the 34th U.S. Symposium on rock mechanics, 27-30 June 1993, University of Wisconsin-Madison. For the covering abstract see IRRD 863389.

696 citations

Journal ArticleDOI
TL;DR: In this paper, a single-face dynamic unloading tests under true-triaxial condition were carried out for Paleozonic marine sedimentation limestone samples produced by blocks cored from 1140m depth in Jiahe coal mine of China.

609 citations