水–力共同作用下预制裂隙类岩石试样裂纹扩展试验研究
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摘要
为研究裂隙岩体在水–力共同作用下的强度变形特征和裂纹扩展规律,使用高强石膏采用预埋薄片法制作含不同角度裂隙的类岩石试样,在围压6 MPa下,分别施加1,3,5 MPa水压,对完整及含不同角度裂隙的试样进行三轴试验,分析力学特性和破坏形态,揭示裂隙岩体在水–力共同作用下的破坏规律。试验表明,含裂隙试样随着水压的增大由延性破坏向脆性破坏转变,三轴压缩强度、峰后残余强度和弹性模量均随水压增大而减小,随裂纹倾角增大而先减小后增大,且水压对含裂隙试样力学特性的削弱程度受预制裂纹倾角的影响。完整试样破坏断裂角随水压增大而增大,并由剪切破坏向劈裂破坏转化。含裂隙试样的破坏形态主要为剪切破坏,当预制裂纹倾角较小时,含裂隙试样破坏形态受水压影响显著,高水压下试样呈"X"型破坏;当预制裂纹倾角较大时破裂面呈单一倾斜面,且角度基本与预制裂纹倾角一致。
Rock-like specimens with different angles of pre-existing cracks,made by embedded thin sheet method,were using to study the fracturing behaviors and mechanical properties of hydro-mechanical coupled cracks. In this study,1,3 and 5 MPa water pressure were applied inside the pre-existing crack respectively and led to the specimen failure with external compression loading under 6 MPa confining pressure. By analyzing the mechanical properties and failure patterns,the test showed that the failure mode changes from ductile failure to brittle failure with the increase of water pressure. The triaxial strength,post-peak residual strength and elastic modulus all decrease when water pressure increases,and decreases firstly and then increases when pre-existing crack?s angle increases. The fracture angles of intact specimens increases with water pressure increases and the failure pattern transforms from shear failure to splitting failure. When the angle of the pre-existing crack is small,the failure mode of cracked specimen affected by water pressure,and X-shaped crack morphology was observed under high water pressure. When the angle of the pre-existing crack between 60°and 90°,the fracture surface presents a single inclined plane,and the angle of the fracture surface is basically identical with the pre-existing crack.
Rock-like specimens with different angles of pre-existing cracks,made by embedded thin sheet method,were using to study the fracturing behaviors and mechanical properties of hydro-mechanical coupled cracks. In this study,1,3 and 5 MPa water pressure were applied inside the pre-existing crack respectively and led to the specimen failure with external compression loading under 6 MPa confining pressure. By analyzing the mechanical properties and failure patterns,the test showed that the failure mode changes from ductile failure to brittle failure with the increase of water pressure. The triaxial strength,post-peak residual strength and elastic modulus all decrease when water pressure increases,and decreases firstly and then increases when pre-existing crack?s angle increases. The fracture angles of intact specimens increases with water pressure increases and the failure pattern transforms from shear failure to splitting failure. When the angle of the pre-existing crack is small,the failure mode of cracked specimen affected by water pressure,and X-shaped crack morphology was observed under high water pressure. When the angle of the pre-existing crack between 60°and 90°,the fracture surface presents a single inclined plane,and the angle of the fracture surface is basically identical with the pre-existing crack.
引文
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[15]王伟,陈曦,田振元,等.不同排水条件下砂岩应力渗流耦合试验研究[J].岩石力学与工程学报,2016,35(增2):3 540-3 551.(WANG Wei,CHEN Xi,TIAN Zhenyuan,et al.Experimental study on stress-seepage coupling properties of sandstone under different drainage conditions[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(Supp.2):3 540-3 551.(in Chinese))
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[17]LIN C,HE J,LI X,et al.An experimental investigation into the effects of the anisotropy of shale on hydraulic fracture propagation[J].Rock Mechanics and Rock Engineering,2016,50(3):1-12.
[2]BOBET A.The initiation of secondary cracks in compression[J].Engineering Fracture Mechanics,2000,66(2):187-219.
[3]BOBET A,EINSTEIN H H.Fracture coalescence in rocktype materials under uniaxial and biaxial compression[J].International Journal of Rock Mechanics and Mining Science,1998,35(7):863-888.
[4]PARK C H,BOBET A.Crack initiation,propagation and coalescence from frictional flaws in uniaxial compression[J].Engineering Fracture Mechanics,2010,77(14):2 727-2 748.
[5]WONG L N Y.Systematic evaluation of cracking behavior in specimens containing single flaws under uniaxial compression[J].International Journal of Rock Mechanics and Mining Sciences,2009,46(2):239-249.
[6]赵程,鲍冲,松田浩,等.数字图像技术在节理岩体裂纹扩展试验中的应用研究[J].岩土工程学报,2015,37(5):944-951.(ZHAO Cheng,BAO Chong,MATSUDA Hiroshi,et al.Application of digital image correlation method in experimental research on crack propagation of brittle rock[J].Chinese Journal of Geotechnical Engineering,2015,37(5):944-951.(in Chinese))
[7]DESBOIS G,H?HNE N,URAI J L,et al.Deformation in cemented mudrock(Callovo-Oxfordian Clay)by microcracking,granular flow and phyllosilicate plasticity:insights from triaxial deformation,broad ion beam polishing and scanning electron microscopy[J].Solid Earth,2017,8:1-30.
[8]姜振泉,季梁军.岩石全应力-应变过程渗透性试验研究[J].岩土工程学报,2001,23(2):153-156.(JIANG Zhenquan,JI Liangjun.The laboratory study on behavior of permeability of rock along the complete stress-strain path[J].Chinese Journal of Geotechnical Engineering,2001,23(2):153-156.(in Chinese))
[9]SOULEY M,HOMAND F,PEPA S,et al.Damage-induced permeability changes in granite:a case example at the URL in Canada[J].International Journal of Rock Mechanics and Mining Sciences,2001,38(2):297-310.
[10]杨永杰,宋扬,陈绍杰.煤岩全应力应变过程渗透性特征试验研究[J].岩土力学,2007,28(2):381-385.(YANG Yongjie,SONGYang,CHEN Shaojie.Test study on permeability properties of coal specimen in complete stress-strain process[J].Rock and Soil Mechanics,2007,28(2):381-385.(in Chinese))
[11]赵延林,曹平,汪亦显,等.裂隙岩体渗流-损伤-断裂耦合模型及其应用[J].岩石力学与工程学报,2008,27(8):477-486.(ZHAOYanlin,CAO Ping,WANG Yixian,et al.Coupling model of seepagedamage-fracture in fractured rock masses and its application[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(8):477-486.(in Chinese))
[12]曹平,杨慧,江学良,等.水岩作用下岩石亚临界裂纹的扩展规律[J].中南大学学报:自然科学版,2010,41(2):649-654.(CAOPing,YANG Hui,JIANG Xueliang,et al.Subcritical crack growth of rock during water-rock interaction[J].Journal of Central South University:Science and Technology,2010,41(2):649-654.(in Chinese))
[13]申林方,冯夏庭,潘鹏志,等.单裂隙花岗岩在应力-渗流-化学耦合作用下的试验研究[J].岩石力学与工程学报,2010,29(7):1 379-1 388.(SHEN Linfang,FENG Xiating,PAN Pengzhi,et al.Experimental research on mechano-hydro-chemical coupling of granite with single fracture[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1 379-1 388.(in Chinese))
[14]李夕兵,贺显群,陈红江.渗透水压作用下类岩石材料张开型裂纹启裂特性研究[J].岩石力学与工程学报,2012,31(7):1 317-1 324.(LI Xibing,HE Xianqun,CHEN Hongjiang.Crack initiation characteristics of opening-mode crack embedded in rock-like material under seepage pressure[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(7):1 317-1 324.(in Chinese))
[15]王伟,陈曦,田振元,等.不同排水条件下砂岩应力渗流耦合试验研究[J].岩石力学与工程学报,2016,35(增2):3 540-3 551.(WANG Wei,CHEN Xi,TIAN Zhenyuan,et al.Experimental study on stress-seepage coupling properties of sandstone under different drainage conditions[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(Supp.2):3 540-3 551.(in Chinese))
[16]BENNOUR Z,ISHIDA T,NAGAYA Y,et al.Crack extension in hydraulic fracturing of shale cores using viscous oil,water,and liquid carbon dioxide[J].Rock Mechanics and Rock Engineering,2015,48(4):1 463-1 473.
[17]LIN C,HE J,LI X,et al.An experimental investigation into the effects of the anisotropy of shale on hydraulic fracture propagation[J].Rock Mechanics and Rock Engineering,2016,50(3):1-12.