真三轴条件下砂岩强度、变形及破坏特征试验研究
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摘要
研究真三轴应力状态下岩石强度、变形及破坏模式对于科学准确地预测和评价地下岩石工程稳定性具有重要的意义。通过自主研制的真三轴电液伺服控制系统开展一系列砂岩真三轴加载试验,结合CT扫描技术,系统研究了不同中间主应力影响下砂岩强度、变形及破裂特征。研究发现:随着中间主应力的增加,砂岩强度呈先增加后减小的趋势;中间主应力的增加促使该加载方向变形逐渐受到抑制,侧向膨胀主要沿最小主应力加载方向,并出现先减小后明显加快的趋势,中间主应力由对岩石的保护作用逐渐演变为损伤作用;真三轴条件下,岩样内部出现两条规则的破裂面,裂纹面沿着σ2方向,倾向于σ3方向,整体破裂形态较规整,岩样破裂面表面积随中间主应力的增加呈先减小后增加的趋势。本文研究成果对于更深入的理解真三轴条件下砂岩力学行为及破坏特征有一定的意义。
It is of great significance to predict and evaluate the stability of underground rock engineering scientifically and accurately to study the strength, deformation and failure behavior of rock under the true triaxial stress condition. This experiment conducts a thorough and systematic study on the strength, deformation and failure characteristics of sandstone by using the self-developed true triaxial electro-hydraulic servo test system and CT scanning technique. Results have been drawn: With the intermediate principal stress increasing, the peak strength of sandstone firstly increases and then decreases. Owing to the increasing intermediate principal stress, the deformation along the direction of the intermediate principal stress is gradually suppressed, while the lateral expansion is mainly along the direction of minimum principal stress and it shows a decreasing trend of expanding and then increasing obviously. The intermediate principal stress gradually evolved into damage from protection on the rock. Under the true triaxial stress condition, there are two regular fracture surfaces which strike along thedirection of applied σ2 and dip towards σ3 in the rock specimen. The fracture surface area decreases firstly and then increases with the increase of the intermediate principal stress. The results are important to further understanding in the mechanical behavior and failure characteristics of sandstone under the true triaxial condition.
It is of great significance to predict and evaluate the stability of underground rock engineering scientifically and accurately to study the strength, deformation and failure behavior of rock under the true triaxial stress condition. This experiment conducts a thorough and systematic study on the strength, deformation and failure characteristics of sandstone by using the self-developed true triaxial electro-hydraulic servo test system and CT scanning technique. Results have been drawn: With the intermediate principal stress increasing, the peak strength of sandstone firstly increases and then decreases. Owing to the increasing intermediate principal stress, the deformation along the direction of the intermediate principal stress is gradually suppressed, while the lateral expansion is mainly along the direction of minimum principal stress and it shows a decreasing trend of expanding and then increasing obviously. The intermediate principal stress gradually evolved into damage from protection on the rock. Under the true triaxial stress condition, there are two regular fracture surfaces which strike along thedirection of applied σ2 and dip towards σ3 in the rock specimen. The fracture surface area decreases firstly and then increases with the increase of the intermediate principal stress. The results are important to further understanding in the mechanical behavior and failure characteristics of sandstone under the true triaxial condition.
引文
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[18]蒋邦友.深部复合地层隧道TBM施工岩爆孕育及控制机理研究[D].徐州:中国矿业大学,2017.
[19]LABUZ J F,BRIDELL J M.Reducing frictional constraint in compression testing through lubrication[J].International Journal of Rock Mechanics and Mining Science and Geomechanics Abstracts,1993,30(4):451-455.
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[22]MA X.Failure characteristics of compactive,porous sand-stones subjected to true triaxial stresses[D].Madison:The University of Wisconsin-Madison,2014.
[2]MOGI K.Fracture and flow of rocks under high triaxial compression[J].Journal of Geophysical Research Atmospheres,1971,76(5):1255-1269.
[3]HAIMSON B,CHANG C.A new true triaxial cell for testing mechanical properties of rock,and its use to determine rock strength and deformability of Westerly granite[J].International Journal of Rock Mechanics and Mining Sciences,2000,37(1):285-296.
[4]CHANG C,HAIMSON B.True triaxial strength and deforma-bility of the German Continental Deep Drilling Program(KTB)deep hole amphibolite[J].Journal of Geophysical Research,2000,105(B8):18999-19013.
[5]HARUYUKI O,BEZALEL H,SONG S.True triaxial strength and deformability of the siltstone overlying the Chelungpu fault(Chi-Chi earthquake),Taiwan[J].Geophysical Research Letters,2007,340(9):139-158.
[6]LEE H,HAIMSON B C.True triaxial strength,deformability,and brittle failure of granodiorite from the San Andreas Fault Observatory at Depth[J].International Journal of Rock Mechanics and Mining Sciences,2011,48(7):1199-1207.
[7]陈景涛,冯夏庭.高地应力下岩石的真三轴试验研究[J].岩石力学与工程学报,2006,25(8):1537-1543.CHEN Jingtao,FENG Xiating.True triaxial experimental study on rock with high geostress[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(8):1537-1543.
[8]FENG X T,ZHANG X,KONG R,et al.A novel Mogi type true triaxial testing apparatus and its use to obtain complete stress-strain curves of hard rocks[J].Rock Mechanics and Rock Engineering,2016,49(5):1649-1662.
[9]HE M C,MIAO J L,FENG J L.Rock burst process of limes-tone and its acoustic emission characteristics under true triaxial unloading conditions[J].International Journal of Rock Mechanics and Mining Sciences,2010,47(2):286-298.
[10]HA M C,NIE W,ZHAO Z Y,et al.Experimental investigation of bedding plane orientation on the rockburst behavior of sandstone[J].Rock Mechanics and Rock Engineering,2012,45(3):311-326.
[11]何满潮,苗金丽,李德建,等.深部花岗岩试样岩爆过程实验研究[J].岩石力学与工程学报,2007,26(5):865-876.HE Manchao,MIAO Jinli,LI Dejian,et al.Experimental study on rockburst process of granite specimen at great depth[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(5):865-876.
[12]苏承东,翟新献,李宝富,等.砂岩单三轴压缩过程中声发射特征的试验研究[J].采矿与安全工程学报,2011,28(2):225-230.SU Chengdong,ZHAI Xinxian,LI Baofu,et al.Experimental study of the characteristics of acoustic emission for sandstone specimens under uniaxial and triaxial compression tests[J].Journal of Mining&Safety Engineering,2011,28(2):225-230.
[13]唐浩,李天斌,陈国庆,等.水力作用下砂岩三轴卸荷试验及破裂特性研究[J].岩土工程学报,2015,37(3):519-525.TANG Hao,LI Tianbin,CHEN Guoqing,et al.Triaxial unloading tests on rupture characteristics of sandstone under hydro-mechanical coupling conditions[J].Chinese Journal of Geotechnical Engineering,2015,37(3):519-525.
[14]卢高明,李元辉.围压对黄砂岩疲劳破坏变形特性的影响[J].岩土力学,2016,37(7):1847-1856.LU Gaoming,LI Yuanhui.Influence of confining pressure on fatigue deformation properties of yellow sandstone[J].Rock and Soil Mechanics,2016,37(7):1847-1856.
[15]杨永明,鞠杨,陈佳亮,等.三轴应力下致密砂岩的裂纹发育特征与能量机制[J].岩石力学与工程学报,2014,33(4):691-698.YANG Yongming,JU Yang,CHEN Jialiang,et al.Cracks development features and energy mechanism of dense sandstone subjected to triaxial stress[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(4):691-698.
[16]杨更社,刘慧.基于CT图像处理技术的岩石损伤特性研究[J].煤炭学报,2007,32(5):463-468.YANG Gengshe,LIU Hui.Study on the rock damage characteristics based on the technique of CT image processing[J].Journal of China Coal Society,2007,32(5):463-468.
[17]RAYNAUD S,NGAN-TILLARD D,DESRUES J,et al.Brittle-to-ductile transition in Beaucaire marl from triaxial tests under the CT-scanner[J].International Journal of Rock Mechanics and Mining Sciences,2008,45(5):653-671.
[18]蒋邦友.深部复合地层隧道TBM施工岩爆孕育及控制机理研究[D].徐州:中国矿业大学,2017.
[19]LABUZ J F,BRIDELL J M.Reducing frictional constraint in compression testing through lubrication[J].International Journal of Rock Mechanics and Mining Science and Geomechanics Abstracts,1993,30(4):451-455.
[20]KAWAKATA H,CHO A,KIYAMA T,et al.Three-dimensional observations of faulting process in Westerly granite under uniaxial and triaxial conditions by X-ray CT scan[J].Tectonophysics,1999,313(3):293-305.
[21]方建银,党发宁,肖耀庭,等.粉砂岩三轴压缩CT试验过程的分区定量研究[J].岩石力学与工程学报,2015,34(10):1976-1984.FANG Jianyin,DANG Faning,XIAO Yaoting,et al.Quantitative study on the CT test process of siltstone under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(10):1976-1984.
[22]MA X.Failure characteristics of compactive,porous sand-stones subjected to true triaxial stresses[D].Madison:The University of Wisconsin-Madison,2014.