单压下有序多裂隙脆性材料破坏机制及其简化模型
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摘要
采用试件养护前期拔出预埋插片形成预制裂隙的方法制作多裂隙脆性材料试件,并在伺服控制单轴加载系统上对其进行加载试验。基于单压下脆性材料局部破损的应变软化机理建立裂隙体数值模型,对比试验与数值计算结果分析有序多裂隙脆性材料破坏机制及其影响因素。结果表明:除裂隙倾角及其几何排布外,裂隙在试件中的相对分布位置也影响裂隙体的破坏特征,且影响程度与裂隙面上有效剪切力大小有关,有效剪切力越大,则影响越显著。试验与数值计算结果显示:多裂隙试件中存在一组优势破坏面,与和裂隙走向相一致的试件斜对角线重合,裂隙分布在优势破坏面上或附近时,其尖端发育微裂纹的机率大于远离优势破坏面位置裂隙。结合有序多裂隙试件破坏特征及数值模型单元屈服状态,提出2种近置裂隙尖端裂纹发育简化模型,并结合本试验结果验证了简化模型的可行性。
The loading tests were done on the brittle specimens with ordered multi-fissures which were made by pulling out the metallic shims at the early stage in the curing process under a uniaxial loading system with servo control.The numerical models of fissure bodies were established based on the strain-softening mechanism of brittle material with local damage characteristics under uniaxial compression.The failure mechanism and its influencing factors of brittle material with ordered multi-fissures were analyzed by comparing experiment results with numerical calculations.The results show that the failure characteristics of specimens are also influenced by the relative position of fissures besides the fissure inclination angle and its geometrical arrangement,and the influence degree has relationship with the effective shear stress on fissure surface.The larger the effective shear stress is,the more significant the influence is.The experimental results and numerical calculations show that a dominant failure surface exists in the specimen with ordered multi-fissures,which is coincident with the diagonal that has the same strike with fissures.The probability of micro-cracks appearing at the tips of fissures,which distribute in or are close to the dominant failure surface,is larger than the probability of the ones which are far from the dominant failure surface.Combined with the failure characteristics of specimens with ordered multi-fissures and yield situations of grid cells in numerical models,two kinds of simplified models are proposed to describe the spatial morphologies of closely-spaced fissures.Then,combined with this experimental result,the feasibility of simplified models is verified.
The loading tests were done on the brittle specimens with ordered multi-fissures which were made by pulling out the metallic shims at the early stage in the curing process under a uniaxial loading system with servo control.The numerical models of fissure bodies were established based on the strain-softening mechanism of brittle material with local damage characteristics under uniaxial compression.The failure mechanism and its influencing factors of brittle material with ordered multi-fissures were analyzed by comparing experiment results with numerical calculations.The results show that the failure characteristics of specimens are also influenced by the relative position of fissures besides the fissure inclination angle and its geometrical arrangement,and the influence degree has relationship with the effective shear stress on fissure surface.The larger the effective shear stress is,the more significant the influence is.The experimental results and numerical calculations show that a dominant failure surface exists in the specimen with ordered multi-fissures,which is coincident with the diagonal that has the same strike with fissures.The probability of micro-cracks appearing at the tips of fissures,which distribute in or are close to the dominant failure surface,is larger than the probability of the ones which are far from the dominant failure surface.Combined with the failure characteristics of specimens with ordered multi-fissures and yield situations of grid cells in numerical models,two kinds of simplified models are proposed to describe the spatial morphologies of closely-spaced fissures.Then,combined with this experimental result,the feasibility of simplified models is verified.
引文
[1]蒲成志,曹平,赵延林,张向阳,衣永亮,刘业科.单轴压缩下多裂隙类岩石材料强度试验与数值分析[J].岩土力学,2010,31(11):3661-3666.PU Cheng-zhi,CAO Ping,ZHAO Yan-lin,ZHANG Xiang-yang,YI Yong-liang,LIU Ye-ke.The numerical analysis and strength experiment of rock-like material with multi-fissures under uniaxial compression[J].Rock and Soil Mechanics,2010,31(11):3661-3666.
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[8]BOBET A.The initiation of secondary cracks in compression[J].Engineering Fracture Mechanics,2000,66:187-219.
[9]PARK C H,BOBET A.Crack coalescence in specimens with open and closed flaws:A comparison[J].International Journal of Rock Mechanics&Mining Sciences,2009,46:819-829.
[10]李银平,杨春和.近置多裂纹相互作用的渐近分析方法[J].力学学报,2005,37(5):600-605.LI Ying-ping,YANG Chun-he.Asymptotic analysis of interaction of closely-spaced cracks[J].Chinese Journal of Theoretical and Applied Mechanics,2005,37(5):600-605.
[11]蒲成志.单轴压缩下类岩体裂隙材料断裂破坏机制的实验研究[D].长沙:中南大学,2010.PU Cheng-zhi.Experiment research on the fracture failure mechanism of rock-like material with fissures under uniaxial compression[D].Changsha:Central South University,2010.
[12]赵延林.裂隙岩体渗流-损伤-断裂耦合理论及应用研究[D].长沙:中南大学,2009.ZHAO Yan-lin.Coupling theory of seepage-damage-fracture in fractured rock masses and its application[D].Changsha:Central South University,2009.
[13]张平.裂隙介质静动应力条件下的破坏模式与局部化渐进破损模型研究[D].西安:西安理工大学,2004.ZHANG Ping.Research on the failure patterns and localized progressive failure models of the cracked media under static and dynamic stress condition[D].Xi’an:Xi’an University of Technology,2004.
[14]HUTCHINSON J W.Crack tip shielding by microcracking in brittle solids[J].Acta Metall,1987,35:1605-1619.
[15]陈蕴生,李宁,韩信,蒲毅彬,廖全荣.非贯通裂隙介质裂隙扩展规律的CT试验研究[J].岩石力学与工程学报,2005,24(15):2665-2670.CHEN Yun-sheng,LI Ning,HAN Xin,PU Yi-bin,LIAO Quan-rong.Research on crack developing process in non-interpenetrated crack media by using CT[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(15):2665-2670.
[2]沈珠江.岩土破损力学与双重介质模型[J].水利水运工程学报,2002,23(4):1-6.SHEN Zhu-jiang.Breakage mechanics and double medium model for geological materials[J].Hydro Science and Engineering,2002,23(4):1-6.
[3]沈珠江.岩土破损力学:理想脆弹塑性模型[J].岩土工程学报,2003,25(3):253-257.SHEN Zhu-jiang.Breakage mechanics for geological materials:An ideal brittle-elasto-plastic model[J].Chinese Journal of Geotechnical Engineering,2003,25(3):253-257.
[4]陈铁林,沈珠江.岩土破损力学的系统论基础[J].岩土力学,2004,25(s2):21-26.CHEN Tie-lin,SHEN Zhu-jiang.System approach of breakage mechanics for geological materials[J].Rock and Soil Mechanics,2004,25(s2):21-26.
[5]黎立云,许凤光,高峰,王利,车发星.岩桥贯通机理的断裂力学分析[J].岩石力学与工程学报,2005,24(23):4328-4334.LI Li-yun,XU Feng-guang,GAO Feng,WANG Li,CHE Fa-xing.Fracture mechanics analysis of rock bridge failure mechanism[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(23):4328-4334.
[6]黄明利,唐春安,梁正召.岩石裂纹相互作用的应力场分析[J].东北大学学报:自然科学版,2001,22(4):446-449.HUANG Ming-li,TANG Chun-an,LIANG Zheng-zhao.Stress field analysis of interaction of rock cracks[J].Journal of Northeastern University:Natural Science,2001,22(4):446-449.
[7]唐春安,黄明利,张国民,焦明若.岩石介质中多裂纹扩展相互作用及其贯通机制的数值模拟[J].地震,2001,21(2):53-58.TANG Chun-an,HUANG Ming-li,ZHANG Guo-min,JIAO Ming-ruo.Numerical simulation on propagation,interaction and coalescence of multi-cracks in rocks[J].Earthquake,2001,21(2):53-58.
[8]BOBET A.The initiation of secondary cracks in compression[J].Engineering Fracture Mechanics,2000,66:187-219.
[9]PARK C H,BOBET A.Crack coalescence in specimens with open and closed flaws:A comparison[J].International Journal of Rock Mechanics&Mining Sciences,2009,46:819-829.
[10]李银平,杨春和.近置多裂纹相互作用的渐近分析方法[J].力学学报,2005,37(5):600-605.LI Ying-ping,YANG Chun-he.Asymptotic analysis of interaction of closely-spaced cracks[J].Chinese Journal of Theoretical and Applied Mechanics,2005,37(5):600-605.
[11]蒲成志.单轴压缩下类岩体裂隙材料断裂破坏机制的实验研究[D].长沙:中南大学,2010.PU Cheng-zhi.Experiment research on the fracture failure mechanism of rock-like material with fissures under uniaxial compression[D].Changsha:Central South University,2010.
[12]赵延林.裂隙岩体渗流-损伤-断裂耦合理论及应用研究[D].长沙:中南大学,2009.ZHAO Yan-lin.Coupling theory of seepage-damage-fracture in fractured rock masses and its application[D].Changsha:Central South University,2009.
[13]张平.裂隙介质静动应力条件下的破坏模式与局部化渐进破损模型研究[D].西安:西安理工大学,2004.ZHANG Ping.Research on the failure patterns and localized progressive failure models of the cracked media under static and dynamic stress condition[D].Xi’an:Xi’an University of Technology,2004.
[14]HUTCHINSON J W.Crack tip shielding by microcracking in brittle solids[J].Acta Metall,1987,35:1605-1619.
[15]陈蕴生,李宁,韩信,蒲毅彬,廖全荣.非贯通裂隙介质裂隙扩展规律的CT试验研究[J].岩石力学与工程学报,2005,24(15):2665-2670.CHEN Yun-sheng,LI Ning,HAN Xin,PU Yi-bin,LIAO Quan-rong.Research on crack developing process in non-interpenetrated crack media by using CT[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(15):2665-2670.
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