期刊
CANADIAN GEOTECHNICAL JOURNAL
卷 52, 期 7, 页码 890-902出版社
CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS
DOI: 10.1139/cgj-2014-0355
关键词
rockburst; strainburst; specimen height-to-width ratio; stress path; true-triaxial unloading; acoustic emission; Tianhu granite
资金
- China Atomic Energy Authority through the Geological Disposal Program
- National Natural Science Foundation of China [11102061]
- Natural Sciences and Engineering Research Council (NSERC) of Canada
- State Key Laboratory for GeoMechanics and Deep Underground Engineering [GDUEKB2013024]
Strainbursts occur frequently near excavation boundaries, posing a significant threat to the safety of workers and stability of underground structures. A better understanding of the strainburst phenomenon is important for safe underground construction and risk management. This paper presents the results of an experimental study on strainburst behaviours of Tianhu granite with four specimen height-to-width (H/W) ratios. A series of tests under unloading conditions were conducted using a true-triaxial strainburst test system that was equipped with an acoustic emission (AE) monitoring system. A high-speed camera was used to capture the instantaneous strainburst process of the specimens on the unloading surface. The experimental results indicate that regardless of the H/W ratio, strainbursts occurred in all specimens but strainburst characteristics depend on the H/Wratio. When the H/W ratio changes from 2.5 to 1.0, the dynamic failure process of the unloading surface transforms from local rock ejection to full-face burst. The strainburst is more violent when the H/W ratio is small. Analysis of the cumulative AE energy revealed that the cumulative AE energy is not sensitive to the H/W ratio for ratios lower than 1.5. When the H/W ratio is greater than 1.5, the cumulative AE energy shows a decreasing trend during rock failure.
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