不同水损伤程度下泥岩断裂力学特性试验研究
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摘要
为研究不同程度水损伤作用对泥岩断裂力学特性的影响,对水中浸泡不同时间条件下的泥岩半圆盘试件进行三点弯曲试验,同时利用PCI–2型声发射系统对泥岩试件的断裂全过程进行实时监测。结果表明:天然泥岩的断裂力学行为受水–岩作用影响显著,随着浸泡时间的增加,其峰值载荷不断下降,浸泡200 min后,该泥岩纯I型至纯II型断裂韧度分别降低至未损伤条件下的53%,56.5%,61%,64%,64.7%和67.6%,且泥岩的断裂破坏形式由脆性逐渐转变为延性。通过声发射定位确定了不同损伤程度下泥岩半圆盘试件中断裂过程区长度,随着损伤程度加深,断裂过程区长度逐渐减小,声发射事件累计总数不断增加;同时,将试验得到的等效断裂韧度与纯I型断裂韧度的比值与引入T应力后改进的最大周向应力理论比值进行比较,表明在未浸泡及短时间浸泡条件下试验结果符合该理论结果;但随着损伤程度的加深该试验结果拟合曲线逐渐偏离理论曲线,浸泡时间达到200 min时,该偏离情况较为明显。
In order to study the effect of water damage on the characteristics of fracturing of mudstone,three-point bending test was carried out to the semi-circular bend(SCB) mudstone specimens that have been soaked in water for different durations. The real-time monitoring with PCI–2 type acoustic emission system was conducted on the fracturing process of the mudstone specimens. The results show that fracturing behaviors of the mudstone is significantly influenced by water-rock interaction. The peak load of the mudstone specimens decreases with the soaking time increases. After being soaked for 200 minutes,the fracture toughness of mudstone from pure mode I to pure mode II decreased respectively to 53%,56.5%,61%,64%,64.7% and 67.6% of those of the intact specimens,and the failure characteristics of mudstone was changed from brittle to ductile. The length of fracture process zone(FPZ) of the mudstone SCB specimens soaked for different durations was confirmed by the acoustic emission(AE) positioning. As the soaking time increases,the length of FPZ decreases and the accumulative number of acoustic emission events increases. The experimental ratio of Keff/KIC and the theoretical ratio based on the modified maximum tangential stress(MMTS) criterion that takes into account the T-stress matched well when the mudstone SCB specimens are not soaked or only soaked for a short time. However,as the soaking time increases,the experimental results of SCB specimens diverge from the theoretical values gradually. When the soaking time reaches 200 minutes,the deviation becomes very distinct.
In order to study the effect of water damage on the characteristics of fracturing of mudstone,three-point bending test was carried out to the semi-circular bend(SCB) mudstone specimens that have been soaked in water for different durations. The real-time monitoring with PCI–2 type acoustic emission system was conducted on the fracturing process of the mudstone specimens. The results show that fracturing behaviors of the mudstone is significantly influenced by water-rock interaction. The peak load of the mudstone specimens decreases with the soaking time increases. After being soaked for 200 minutes,the fracture toughness of mudstone from pure mode I to pure mode II decreased respectively to 53%,56.5%,61%,64%,64.7% and 67.6% of those of the intact specimens,and the failure characteristics of mudstone was changed from brittle to ductile. The length of fracture process zone(FPZ) of the mudstone SCB specimens soaked for different durations was confirmed by the acoustic emission(AE) positioning. As the soaking time increases,the length of FPZ decreases and the accumulative number of acoustic emission events increases. The experimental ratio of Keff/KIC and the theoretical ratio based on the modified maximum tangential stress(MMTS) criterion that takes into account the T-stress matched well when the mudstone SCB specimens are not soaked or only soaked for a short time. However,as the soaking time increases,the experimental results of SCB specimens diverge from the theoretical values gradually. When the soaking time reaches 200 minutes,the deviation becomes very distinct.
引文
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[7]周翠英,邓毅梅,谭祥韶,等.饱水软岩力学性质软化的试验研究与应用[J].岩石力学与工程学报,2005,24(1):33–38.(ZHOU Cuiying,DENG Yimei,TAN Xiangshao,et al.Experimental research on the softening of mechanical properties of saturated soft rocks and application[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(1):33–38.(in Chinese))
[8]周翠英,谭祥韶,邓毅梅,等.特殊软岩软化的微观机制研究[J].岩石力学与工程学报,2005,24(3):394–400.(ZHOU Cuiying,TAN Xiangshao,DENG Yimei,et al.Research on softening micromechanism of special soft rocks[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(3):394–400.(in Chinese))
[9]GHORBANI A,ZAMORA M,COSENZA P.Effects of desiccation on the elastic wave velocities of clay-rocks[J].International Journal of Rock Mechanics and Mining Sciences,2009,46(8):1 267–1 272.
[10]陈建国,邓金根,袁俊亮,等.页岩储层I型和II型断裂韧性评价方法研究[J].岩石力学与工程学报,2015,34(6):1 101–1 105.(CHEN Jianguo,DENG Jingen,YUAN Junliang,et al.Determination of fracture toughness of modes I and II of shale formation[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(6):1 101–1 105.(in Chinese))
[11]王蒙,朱哲明,王雄.冲击荷载作用下的I/II复合型裂纹扩展规律研究[J].岩石力学与工程学报,2016,35(7):1 323–1 332.(WANG Meng,ZHU Zheming,WANG Xiong.The growth of mixed-mode I/II crack under impacting loads[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(7):1 323–1 332.(in Chinese))
[12]陈明,郭天阳,卢文波,等.爆破开挖对边坡岩体裂纹扩展的扰动机制[J].岩石力学与工程学报,2015,34(7):1 307–1 314.(CHEN Ming,GUO Tianyang,LU Wenbo,et al.Disturbance of blasting excavation on crack growth in rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1 307–1 314.(in Chinese))
[13]黄建安,王思敬.岩石断裂韧性的试验研究[J].岩土工程学报,1982,4(2):67–75.(HANG Jian?an,WANG Sijing.Experimental study of the fracture toughness of rock[J].Chinese Journal of Geotechnical Engineering,1982,4(2):67–75.(in Chinese))
[14]许媛,戴峰,徐奴文,等.人字形切槽巴西圆盘岩石试样复合型断裂渐进过程数值模拟研究[J].岩土工程学报,2015,37(12):2 189–2 197.(XU Yuan,DAI Feng,XU Nuwen,et al.Numerical analysis of mixed mode progressive rock fracture mechanism of cracked chevron notched Brazilian disc specimens[J].Chinese Journal of Geotechnical Engineering,2015,37(12):2 189–2 197.(in Chinese))
[15]MACCAGNO T M,KNOTT J F.The fracture behaviour of PMMA in mixed modes I and II[J].Engineering Fracture Mechanics,1989,34(1):65–86.
[16]CHONG K P,KURUPPU M D.New specimen for fracture toughness determination for rock and other materials[J].International Journal of Fracture,1984,26(2):59–62.
[17]KURUPPU M D,OBARA Y,AYATOLLAHI M R,et al.ISRM-suggested method for determining the mode I static fracture toughness using semi-circular bend specimen[M].[S.l.]:Springer International Publishing,2013:267–274.
[18]AYATOLLAHI M R,ALIHA M R M.Fracture parameters for a cracked semi-circular specimen[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(3):20–25.
[19]黄宏伟,车平.泥岩遇水软化微观机理研究[J].同济大学学报:自然科学版,2007,35(7):866–870.(HUANG Hongwei,CHE Ping.Research on Micro-mechanism of Softening and argillitization of mudstone[J].Journal of Tongji University:Natural Science,2007,35(7):866–870.(in Chinese))
[20]OTSUKA K,DATE H.Fracture process zone in concrete tension specimen[J].Engineering Fracture Mechanics,2000,65(2):111–131.
[21]卿龙邦,李庆斌,管俊峰.混凝土断裂过程区长度计算方法研究[J].工程力学,2012,29(4):197–201.(QING Longbang,LI Qingbin,GUAN Junfeng.Calculation method of the length of fracture process zone of concrete[J].Engineering Mechanics,2012,29(4):197–201.(in Chinese))
[22]WANG C,LIU P,HU R,et al.Study of the fracture process zone in rock by laser speckle interferometry[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1990,27(1):65–69.
[23]OHTSU M,KAMINAGA Y,MUNWAM M C.Experimental and numerical crack analysis of mixed-mode failure in concrete by acoustic emission and boundary element method[J].Construction and Building Materials,1999,13(1):57–64.
[24]ERDOGAN F,SIH G C.On the crack extension in plates under plane loading and transverse shear[J].Journal of Basic Engineering,1963,85(4):527.
[25]SIH G C.Strain-energy-density factor applied to mixed mode crack problems[J].International Journal of Fracture,1974,10(3):305–321.
[26]HUSSAIN M A,PU S L,UNDERWOOD J.Strain energy release rate for a crack under combined mode I and mode II[C]//Proceedings of the 1973 National Symposium on Fracture Mechanics.[S.l.]:[s.n.],1974:2–28.
[27]COTTERELL B,RICE J R.Slightly curved or kinked cracks[J].International Journal of Fracture,1980,16(2):155–169.
[28]唐世斌,黄润秋,唐春安,等.T应力对岩石裂纹扩展路径及起裂强度的影响研究[J].岩土力学,2016,37(6):1 521–1 529.(TANG Shibin,HUANG Runqiu,TANG Chun?an,et al.Effect of T-stress on crack growth path in rock and fracture strength[J].Rock and Soil Mechanics,2016,37(6):1 521–1 529.(in Chinese))
[29]WILLIAMS M L.On the stress distribution at the base of a stationary crack[J].ASME Journal of Applied Mechanics,1957,24:109–114.
[30]AYATOLLAHI M R,ALIHA M R M.Wide range data for crack tip parameters in two disc-type specimens under mixed mode loading[J].Computational Materials Science,2007,38(4):660–670.
[2]李汝成,王复明.降雨入渗对泥岩–土混填路堤稳定性的影响[J].岩石力学与工程学报,2008,27(11):2 260–2 266.(LI Rucheng,WANG Fuming.Effect of rainfall infiltration on stability of mudstone-soil mixture embankment[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2 260–2 266.(in Chinese))
[3]黄小兰,杨春和,刘建军,等.不同含水情况下的泥岩蠕变试验及其对油田套损影响研究[J].岩石力学与工程学报,2008,27(增2):3 477–3 482.(HUANG Xiaolan,YANG Chunhe,LIU Jianjun,et al.Experimental study on mudstone?s creep behavior under different water contents and its effect on casing damage[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(Supp.2):3 477–3 482.(in Chinese))
[4]杨建林,王来贵,李喜林,等.遇水–风干循环作用下泥岩断裂的微观机制研究[J].岩石力学与工程学报,2014,33(增2):3 606–3 612.(YANG Jianlin,WANG Laigui,LI Xilin,et al.Research on micro-fracture mechanism of mudstone after wet-dry cycles[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.2):3 606–3 612.(in Chinese))
[5]谌文武,林高潮,刘伟,等.全风化灰绿色及红色泥岩物理力学性质对比研究[J].岩石力学与工程学报,2016,35(12):2 572–2 582.(CHEN Wenhu,LIN Gaochao,LIU Wei,et al.Physical and mechanical properties of weathered green and red mudstones[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(12):2 572–2 582.(in Chinese))
[6]熊德国,赵忠明,苏承东,等.饱水对煤系地层岩石力学性质影响的试验研究[J].岩石力学与工程学报,2011,30(5):998–1 006.(XIONG Deguo,ZHAO Zhongming,SU Chengdong,et al.Experimental study of effect of water-saturated state on mechanical properties of rock in coal measure strata[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(5):998–1 006.(in Chinese))
[7]周翠英,邓毅梅,谭祥韶,等.饱水软岩力学性质软化的试验研究与应用[J].岩石力学与工程学报,2005,24(1):33–38.(ZHOU Cuiying,DENG Yimei,TAN Xiangshao,et al.Experimental research on the softening of mechanical properties of saturated soft rocks and application[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(1):33–38.(in Chinese))
[8]周翠英,谭祥韶,邓毅梅,等.特殊软岩软化的微观机制研究[J].岩石力学与工程学报,2005,24(3):394–400.(ZHOU Cuiying,TAN Xiangshao,DENG Yimei,et al.Research on softening micromechanism of special soft rocks[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(3):394–400.(in Chinese))
[9]GHORBANI A,ZAMORA M,COSENZA P.Effects of desiccation on the elastic wave velocities of clay-rocks[J].International Journal of Rock Mechanics and Mining Sciences,2009,46(8):1 267–1 272.
[10]陈建国,邓金根,袁俊亮,等.页岩储层I型和II型断裂韧性评价方法研究[J].岩石力学与工程学报,2015,34(6):1 101–1 105.(CHEN Jianguo,DENG Jingen,YUAN Junliang,et al.Determination of fracture toughness of modes I and II of shale formation[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(6):1 101–1 105.(in Chinese))
[11]王蒙,朱哲明,王雄.冲击荷载作用下的I/II复合型裂纹扩展规律研究[J].岩石力学与工程学报,2016,35(7):1 323–1 332.(WANG Meng,ZHU Zheming,WANG Xiong.The growth of mixed-mode I/II crack under impacting loads[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(7):1 323–1 332.(in Chinese))
[12]陈明,郭天阳,卢文波,等.爆破开挖对边坡岩体裂纹扩展的扰动机制[J].岩石力学与工程学报,2015,34(7):1 307–1 314.(CHEN Ming,GUO Tianyang,LU Wenbo,et al.Disturbance of blasting excavation on crack growth in rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1 307–1 314.(in Chinese))
[13]黄建安,王思敬.岩石断裂韧性的试验研究[J].岩土工程学报,1982,4(2):67–75.(HANG Jian?an,WANG Sijing.Experimental study of the fracture toughness of rock[J].Chinese Journal of Geotechnical Engineering,1982,4(2):67–75.(in Chinese))
[14]许媛,戴峰,徐奴文,等.人字形切槽巴西圆盘岩石试样复合型断裂渐进过程数值模拟研究[J].岩土工程学报,2015,37(12):2 189–2 197.(XU Yuan,DAI Feng,XU Nuwen,et al.Numerical analysis of mixed mode progressive rock fracture mechanism of cracked chevron notched Brazilian disc specimens[J].Chinese Journal of Geotechnical Engineering,2015,37(12):2 189–2 197.(in Chinese))
[15]MACCAGNO T M,KNOTT J F.The fracture behaviour of PMMA in mixed modes I and II[J].Engineering Fracture Mechanics,1989,34(1):65–86.
[16]CHONG K P,KURUPPU M D.New specimen for fracture toughness determination for rock and other materials[J].International Journal of Fracture,1984,26(2):59–62.
[17]KURUPPU M D,OBARA Y,AYATOLLAHI M R,et al.ISRM-suggested method for determining the mode I static fracture toughness using semi-circular bend specimen[M].[S.l.]:Springer International Publishing,2013:267–274.
[18]AYATOLLAHI M R,ALIHA M R M.Fracture parameters for a cracked semi-circular specimen[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(3):20–25.
[19]黄宏伟,车平.泥岩遇水软化微观机理研究[J].同济大学学报:自然科学版,2007,35(7):866–870.(HUANG Hongwei,CHE Ping.Research on Micro-mechanism of Softening and argillitization of mudstone[J].Journal of Tongji University:Natural Science,2007,35(7):866–870.(in Chinese))
[20]OTSUKA K,DATE H.Fracture process zone in concrete tension specimen[J].Engineering Fracture Mechanics,2000,65(2):111–131.
[21]卿龙邦,李庆斌,管俊峰.混凝土断裂过程区长度计算方法研究[J].工程力学,2012,29(4):197–201.(QING Longbang,LI Qingbin,GUAN Junfeng.Calculation method of the length of fracture process zone of concrete[J].Engineering Mechanics,2012,29(4):197–201.(in Chinese))
[22]WANG C,LIU P,HU R,et al.Study of the fracture process zone in rock by laser speckle interferometry[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1990,27(1):65–69.
[23]OHTSU M,KAMINAGA Y,MUNWAM M C.Experimental and numerical crack analysis of mixed-mode failure in concrete by acoustic emission and boundary element method[J].Construction and Building Materials,1999,13(1):57–64.
[24]ERDOGAN F,SIH G C.On the crack extension in plates under plane loading and transverse shear[J].Journal of Basic Engineering,1963,85(4):527.
[25]SIH G C.Strain-energy-density factor applied to mixed mode crack problems[J].International Journal of Fracture,1974,10(3):305–321.
[26]HUSSAIN M A,PU S L,UNDERWOOD J.Strain energy release rate for a crack under combined mode I and mode II[C]//Proceedings of the 1973 National Symposium on Fracture Mechanics.[S.l.]:[s.n.],1974:2–28.
[27]COTTERELL B,RICE J R.Slightly curved or kinked cracks[J].International Journal of Fracture,1980,16(2):155–169.
[28]唐世斌,黄润秋,唐春安,等.T应力对岩石裂纹扩展路径及起裂强度的影响研究[J].岩土力学,2016,37(6):1 521–1 529.(TANG Shibin,HUANG Runqiu,TANG Chun?an,et al.Effect of T-stress on crack growth path in rock and fracture strength[J].Rock and Soil Mechanics,2016,37(6):1 521–1 529.(in Chinese))
[29]WILLIAMS M L.On the stress distribution at the base of a stationary crack[J].ASME Journal of Applied Mechanics,1957,24:109–114.
[30]AYATOLLAHI M R,ALIHA M R M.Wide range data for crack tip parameters in two disc-type specimens under mixed mode loading[J].Computational Materials Science,2007,38(4):660–670.