Effects of pressure relief holes on coal burst:Insights from true-triaxial unloading tests  

作　　者：Fuqiang Ren Murat Karakus Giang Nguyen Thomas Bruning 

机构地区：[1]School of Civil Engineering,University of Science and Technology Liaoning,Anshan,114051,China [2]Mining and Petroleum Engineering,The University of Adelaide,Adelaide,South Australia,5005,Australia [3]State Key Laboratory for Geomechanics&Deep Underground Engineering,China University of Mining and Technology,Beijing,100083,China [4]School of Architecture and Civil Engineering,The University of Adelaide,South Australia,5005,Australia

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第9期3378-3394,共17页岩石力学与岩土工程学报（英文版）

基　　金：financial support from the Australian Coal Association Research Program(ACARPdC27020-Extension);the China Scholarship Council.

摘　　要：Drilling pressure relief is one of the methods to reduce the risk of coal bursts in deep mines.However,the effect of the drill hole orientations has not been studied well enough to understand their impact on the burst failure mechanism.In this study,we investigated two designs of drill hole orientations.The first design includes drill holes located on the upper free face of the rectangular samples and labelled as upper hole(UH)and centre hole(CH)e the long axes of the drill holes are aligned with minor principal stress,s3,direction.The second design includes drill holes at the top(TH)and the side(SH)of the rectangular samples in which the long axes of the drill holes are aligned with the maximum,s1,and intermediate principal stress,s2,directions,respectively.The coal samples with the proposed drill hole orientations were subjected to the true-triaxial unloading coal burst tests.The results show that the drill holes reduce the risk of coal bursts.However,we found that the intensity of coal burst was significantly reduced with the SH-type,followed by the CH-types.We also observed that the coal burst intensity is reduced better for the CH,UH,TH,and SH-type drilling patterns.However,it was found that the orientations of drill holes have little influence on the failure mode(splitting).The acoustic emission(AE)activities for coal with drill holes noticeably decreased,especially for the UH and CH layouts.The drill holes reduced the upper limit of the AE entropy(chaos of microcracks generation).However,regarding reducing the coal burst risk,the TH and SH are less effective than UH and CH.

关 键 词：Coal burst Triaxial unloading Drilling orientation Ejection characteristic Acoustic emission(AE) 

分 类 号：TU4[建筑科学—土工工程]