不同卸荷速率下矩形巷道变形及声发射特性试验研究
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摘要
为研究矩形巷道在不同开挖卸荷速率条件下的变形规律和声发射特性,使用水泥砂浆矩形巷道围岩试件进行快、慢速开挖卸荷试验,得到顶板、隅角、帮部围岩的应变特征和声发射(AE)撞击计数、能量、频谱的演化特点。试验结果表明:(1)快速卸荷,应变释放率高,卸荷后变形不稳定;而慢速卸荷,围岩应力充分调整,有利于应变的充分释放,卸荷后变形相对稳定。(2)矩形巷道的快、慢速卸荷,均以顶板和帮部围岩的径向受拉、隅角围岩的切向受压变形为主;随围岩深度增加,卸荷效应的影响逐渐减弱。(3)两种卸荷速率的AE撞击计数和能量演化特征与应变特性形成良好对应,揭示了围岩内部裂隙与损伤随开挖卸荷的发展过程;峰值频率区段变宽和高幅值信号的峰值频率在某一频段增多的现象可看作围岩发生主破裂的前兆信息。(4)快速卸荷,顶板和帮部周边产生大块剥落现象;而慢速卸荷,顶板和帮部周边每隔一段距离产生垂直于隅角的贯通裂缝,碎胀现象明显但未脱落;两者的隅角围岩破坏程度均较小。
Under fast and slow excavation unloading rates, experiments were carried out on the surrounding rock specimens of the cement mortar to study the deformation law and acoustic emission characteristics of the rectangular roadway. The strain characteristics of surrounding rock and the evolution characteristics of AE impact count, energy and spectrum were obtained in this study. The test results showed that under rapid unloading, the strain release rate was high, and the deformation was unstable after unloading. However, under slow unloading, the surrounding rock stress was fully adjusted, which was conducive to the full release of strain, and the deformation developed relatively stable after unloading. Under the two unloading modes, the surrounding rock of the roof and the gang in the rectangular roadway were mainly subjected to the radial tensile deformation, while the surrounding rock of the corner mainly experienced the tangential compression deformation. As the depth of the surrounding rock increased, the unloading effect gradually decreased. The AE impact count and energy evolution characteristics of the two unloading rates were well correlated with the strain characteristics, revealing the development process of cracks and damages in the surrounding rock under excavation unloading. The precursor information of the main rupture of the surrounding rock can be referred to the increases of the width of peak frequency band and the number of the peak frequency of the high amplitude signal in a certain frequency band. Under rapid unloading, large pieces of flaking occurred around the roof and the gang. Under slow unloading, the through cracks perpendicular to the corners were generated at intervals around the roof and the gang, and the roof and the gang swelled obviously but didn't fall off. The damage of the right-angle rock was small in these two states.
Under fast and slow excavation unloading rates, experiments were carried out on the surrounding rock specimens of the cement mortar to study the deformation law and acoustic emission characteristics of the rectangular roadway. The strain characteristics of surrounding rock and the evolution characteristics of AE impact count, energy and spectrum were obtained in this study. The test results showed that under rapid unloading, the strain release rate was high, and the deformation was unstable after unloading. However, under slow unloading, the surrounding rock stress was fully adjusted, which was conducive to the full release of strain, and the deformation developed relatively stable after unloading. Under the two unloading modes, the surrounding rock of the roof and the gang in the rectangular roadway were mainly subjected to the radial tensile deformation, while the surrounding rock of the corner mainly experienced the tangential compression deformation. As the depth of the surrounding rock increased, the unloading effect gradually decreased. The AE impact count and energy evolution characteristics of the two unloading rates were well correlated with the strain characteristics, revealing the development process of cracks and damages in the surrounding rock under excavation unloading. The precursor information of the main rupture of the surrounding rock can be referred to the increases of the width of peak frequency band and the number of the peak frequency of the high amplitude signal in a certain frequency band. Under rapid unloading, large pieces of flaking occurred around the roof and the gang. Under slow unloading, the through cracks perpendicular to the corners were generated at intervals around the roof and the gang, and the roof and the gang swelled obviously but didn't fall off. The damage of the right-angle rock was small in these two states.
引文
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[15]侯公羽,李小瑞,张振铎,等.使用小型围岩试件模拟与再现巷道围岩开挖卸荷过程的试验系统[J].岩石力学与工程学报, 2017, 36(9):2136-2145.HOU Gong-yu, LI Xiao-rui, ZHANG Zhen-duo, et al.Experimental system for simulating excavation unloading process of rock around roadway by using small cylindrical hollow specimen[J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(9):2136-2145.
[16] MANOUCHEHRIAN A, CAI M. Simulation of unstable rock failure under unloading conditions[J]. Canadian Geotechnical Journal, 2015, 53(1):22-34.
[17]赵兴东,唐春安,李元辉,等.花岗岩破裂全过程的声发射特性研究[J].岩石力学与工程学报, 2016, 25(2):3673-3678.ZHAO Xing-dong, TANG Chun-an, LI Yuan-hui, et al.Study on an activity characteristics under uniaxial compression loading[J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 25(2):3673-3678.
[18]纪洪广,卢翔.常规三轴压缩下花岗岩声发射特征及其主破裂前兆信息研究[J].岩石力学与工程学报,2015, 34(4):394-702.JI Hong-guang, LU Xiang. Characteristics of acoustic emission and rock fracture precursors of granite under conventional triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(4):394-702.
[2]黄润秋,黄达.高地应力条件下卸荷速率对锦屏大理岩力学特性影响规律试验研究[J].岩石力学与工程学报, 2010, 29(1):21-33.HUANG Run-qiu, HUANG Da. Experimental research on affection laws of unloading rates on mechanical properties of Jinping marble under high geostress[J].Chinese Journal of Rock Mechanics and Engineering,2010, 29(1):21-33.
[3] WANG S F, LI X B, DU K, et al. Experimental study of the triaxial strength properties of hollow cylindrical granite specimens under coupled external and internal confining stresses[J]. Rock Mechanics and Rock Engineering, 2018, 51:2015-2031.
[4] YAHG S Q. Experimental study on deformation, peak strength and crack damage behavior of hollow sandstone under conventional triaxial compression[J]. Engineering Geology, 2016, 213:11-24.
[5]殷志强,李夕兵,金解放,等.围压卸载速度对岩石动力强度与破碎特性的影响[J].岩土工程学报, 2011,33(8):1296-1301.YIN Zhi-qiang, LI Xi-bing, JIN Jie-fang, et al. Effects of unloading rates of confining pressure on dynamic strength and fragmentation characteristics of rock under impact loads[J]. Chinese Journal of Geotechnical Engineering,2011, 33(8):1296-1301.
[6] LI X B, FENG F, LI D Y, et al. Failure characteristics of granite influenced by sample height-to-width ratios and intermediate principal stress under true-triaxial unloading conditions[J]. Rock Mechanics and Rock Engineering,2018, 51(5):1321-1345.
[7] ZHAO X G, WANG J, CAI M, et al. Influence of unloading rate on the strain burst characteristics of Beishan granite under true-triaxial unloading conditions[J]. Rock Mechanics and Rock Engineering,2014, 47(2):467-483.
[8] DU K, TAO M, LI X B, et al. Experimental study of slabbing and rock burst induced by true-triaxial unloading and local dynamic disturbance[J]. Rock Mechanics and Rock Engineering, 2016, 49(9):3437-3453.
[9] HU X C, SU G S, CHEN G Y, et al. Experiment on rockburst process of borehole and its acoustic emission characteristics[J]. Rock Mechanics and Rock Engineering, 2019, 52(3):783-802.
[10]侯公羽,李小瑞,梁洪垚,等.高强石膏材料配比研究及其在围岩试件(厚壁圆筒)开挖卸荷试验中的应用[J].岩土力学, 2018, 39(增刊1):159-166.HOU Gong-yu, LI Xiao-rui, LIANG Hong-yao, et al.Research on proportion of high strength gypsum materials and its application to excavation unloading test of surrounding rock specimen(thick wall cylinder)[J]. Rock and Soil Mechanics, 2018, 39(Suppl.1):159-166.
[11]侯公羽,李小瑞,梁洪垚,等.使用石膏围岩试件模拟巷道开挖卸荷效应的试验研究[J].煤炭学报, 2018,43(3):616-625.HOU Gong-yu, LI Xiao-rui, LIANG Hong-yao, et al.Study on deformation and failure of high-strength gypsum surrounding rock specimens(thick-walled cylinder)simulating roadway excavation[J]. Journal of China Coal Society, 2018, 43(3):616-625.
[12]李为腾,李术才,王琦,等.深部厚顶煤巷道围岩变形破坏机制模型试验研究[J].岩土力学, 2013, 34(10):2847-2856.LI Wei-teng, LI Shu-cai, WANG Qi, et al. Model test study of surrounding rock deformation and failure mechanism of deep roadway with thick top coal[J]. Rock and Soil Mechanics, 2013, 34(10):2847-2856.
[13] BAI J B, SHEN W L, GUO G L, et al. Roof deformation,failure characteristics, and preventive techniques of gob-side entry driving heading adjacent to the advancing working face[J]. Rock Mechanics and Rock Engineering, 2015, 48(6):2447-2458.
[14]李廷春,卢振,刘建章,等.泥化弱胶结软岩地层中矩形巷道的变形破坏过程分析[J].岩土力学, 2014, 35(4):1076-1083.LI Ting-chun, LU Zhen, LIU Jian-zhang, et al.Deformation and failure process analysis of rectangular roadway in muddy weakly cemented soft rock strata[J].Rock and Soil Mechanics, 2014, 35(4):1076-1083.
[15]侯公羽,李小瑞,张振铎,等.使用小型围岩试件模拟与再现巷道围岩开挖卸荷过程的试验系统[J].岩石力学与工程学报, 2017, 36(9):2136-2145.HOU Gong-yu, LI Xiao-rui, ZHANG Zhen-duo, et al.Experimental system for simulating excavation unloading process of rock around roadway by using small cylindrical hollow specimen[J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(9):2136-2145.
[16] MANOUCHEHRIAN A, CAI M. Simulation of unstable rock failure under unloading conditions[J]. Canadian Geotechnical Journal, 2015, 53(1):22-34.
[17]赵兴东,唐春安,李元辉,等.花岗岩破裂全过程的声发射特性研究[J].岩石力学与工程学报, 2016, 25(2):3673-3678.ZHAO Xing-dong, TANG Chun-an, LI Yuan-hui, et al.Study on an activity characteristics under uniaxial compression loading[J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 25(2):3673-3678.
[18]纪洪广,卢翔.常规三轴压缩下花岗岩声发射特征及其主破裂前兆信息研究[J].岩石力学与工程学报,2015, 34(4):394-702.JI Hong-guang, LU Xiang. Characteristics of acoustic emission and rock fracture precursors of granite under conventional triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(4):394-702.
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