冻融循环作用下岩石表面裂纹扩展过程细观研究
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摘要
对页岩进行冻融循环试验,借助激光扫描显微镜对岩石在垂直和平行层理两个方向上的表面裂纹的扩展过程展开细观研究。采用数值模拟对冻融循环作用的温度应力分布、裂纹扩展过程及其机制进行研究。研究结果表明:裂纹深度、裂纹宽度和表面积比均随着冻融循环次数的增加而增大。部分颗粒在冻融循环作用下会发生破碎和崩落。垂直层理的岩石表面的裂纹深度、裂纹宽度和表面积比的增幅较小,曲线较平缓。而平行层理的岩石表面的裂纹深度、裂纹宽度和表面积比的增幅较大,曲线较陡。层理面表现出较为明显的弱面特征。裂纹更容易沿着层理面扩展。裂纹的形成和扩展会导致应力场的重分布。应力集中现象出现在层理面与表面的交界处。表面裂纹大都发端于表面层的自由边界,而后向内部扩展。
Development of rock surface crack in the directions of perpendicular and parallel to the stratification under freeze-thaw cycles is studied at meso-scale by laser scanning microscope. A stratification contained numerical model is simulated to study the stress distribution, fracture propagation and the mechanism of edge fracturing due to freeze-thaw cycles. The results show that: crack depth, crack width and surface area ratio increase with freeze-thaw cycles. Some particles crush and spall by freezing and thawing cycles. Crack depth,crack width and surface area ratio increase slightly for parallel stratification condition while significantly for perpendicular stratification. Stratification is regarded as weak plane where cracks may first initiate and propagate. Formation and propagation of crack lead to redistribution of stress field. Stress concentrates in the intersection of stratification and surface. Most of cracks initiate from the surface.
Development of rock surface crack in the directions of perpendicular and parallel to the stratification under freeze-thaw cycles is studied at meso-scale by laser scanning microscope. A stratification contained numerical model is simulated to study the stress distribution, fracture propagation and the mechanism of edge fracturing due to freeze-thaw cycles. The results show that: crack depth, crack width and surface area ratio increase with freeze-thaw cycles. Some particles crush and spall by freezing and thawing cycles. Crack depth,crack width and surface area ratio increase slightly for parallel stratification condition while significantly for perpendicular stratification. Stratification is regarded as weak plane where cracks may first initiate and propagate. Formation and propagation of crack lead to redistribution of stress field. Stress concentrates in the intersection of stratification and surface. Most of cracks initiate from the surface.
引文
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[18]陈从新,刘秀敏,刘才华.数字图像技术在岩石细观力学研究中的应用[J].岩土力学,2010,31(S1):53-61(Chen Congxin,Liu Xiumin,Liu Caihua.Application of digital image processing to rock mesomechanics[J].Rock and Soil Mechanics,2010,31(S1):53-61(in Chinese))
[19]刘恺德,刘泉声,朱元广,等.考虑层理方向效应煤岩巴西劈裂及单轴压缩试验研究[J].岩石力学与工程学报,2013,32(2):308-316(Liu Kaide,Liu Quansheng,Zhu Yuanguang,et al.Experimental study of coal considering directivity effect of stratification plane under brazilian splitting and uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):308-316(in Chinese))
[20]包春燕,唐春安,唐世斌,等.温缩等间距表面裂纹扩展的数值模拟及其机制研究[J].岩石力学与工程学报,2014,33(3):549-557(Bao Chunyan,Tang Chun’an,Tang Shibin,et al.Numerical simulation and mechanism research of surface fracture equal-spacing subjected to cooling shrinking[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(3):549-557(in Chinese))
[2]刘红岩,刘冶,邢闯锋,等.循环冻融条件下节理岩体损伤破坏试验研究[J].岩土力学,2014,35(6):1547-1554(Liu Hongyan,Liu Ye,Xing Chuangfeng,et al.Test study of damage failure of jointed rock mass under freezing-thawing cycles[J].Rock and Soil Mechanics,2014,35(6):1547-1554(in Chinese))
[3]巫锡勇,朱宝龙,罗健.黑色岩层的风化过程及其热力学分析[M].北京:科学出版社,2008
[4]Yavuz H,Altindag R,Sarac S,et al.Estimating the index properties of deteriorated carbonate rocks due to freeze-thaw and thermal shock weathering[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(5):767-775
[5]Bayram F.Predicting mechanical strength loss of natural stones after freeze-thaw in cold regions[J].Cold Regions Science and Technology,2012,83/84:98-102
[6]刘华,牛富俊,徐志英,等.循环冻融条件下安山岩和花岗岩的物理力学特性试验研究[J].冰川冻土,2011,33(3):557-563(Liu Hua,Niu Fujun,Xu Zhiying,et al.Acoustic experimental study of two types of rock from the Tibetan Plateau under the condition of freeze-thaw cycles[J].Sciences in Cold and Arid Regions,2011,33(3):557-563(in Chinese))
[7]杨更社,张全胜,蒲毅彬.冻结温度对岩石细观损伤扩展特性影响研究初探[J].岩土力学,2004,25(9):1409-1413(Yang Gengshe,Zhang Quansheng,Pu Yibin.Preliminary study on meso-damage propagation characteristics of rock under condition of freezing temperature[J].Rock and Soil Mechanics,2004,25(9):1409-1413(in Chinese))
[8]许玉娟,周科平,李杰林,等.冻融岩石核磁共振检测及冻融损伤机制分析[J].岩土力学,2012,33(10):3001-3005(Xu Yujuan,Zhou Keping,Li Jielin,et al.Study of rock NMR experiment and damage mechanism analysis under freeze-thaw condition[J].Rock and Soil Mechanics,2012,33(10):3001-3005(in Chinese))
[9]李杰林,周科平,张亚民,等.基于核磁共振技术的岩石孔隙结构冻融损伤试验研究[J].岩石力学与工程学报,2012,31(6):1208-1214(Li Jielin,Zhou Keping,Zhang Yamin,et al.Experimental study of rock porous structure damage characteristics under condition of freezing-thawing cycles based on nuclear magnetic resonance technique[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(6):1208-1214(in Chinese))
[10]Taber S.Frost heaving[J].The Journal of Geology,1929,37(5):428-461
[11]Taber S.The mechanics of frost heaving[J].The Journal of Geology,1930,38(4):303-317
[12]Sass O.Rock moisture fluctuations during freeze-thaw cycles:preliminary results from electrical resistivity measurements[J].Polar Geography,2004,28(1):13-31
[13]Everett D H.The thermodynamics of frost damage to porous solids[J].Transactions of the Faraday Society,1961,57:1541-1551
[14]Miller R D.Freezing and heaving of saturated and unsaturated soils[J].Highway Research Record,1972,393:1-11
[15]Murton J B,Peterson R,Ozouf J C.Bedrock fracture by ice segregation in cold regions[J].Science,2006,314(5802):1127-1129
[16]杨更社,周春华,田应国,等.软岩类材料冻融过程水热迁移的实验研究初探[J].岩石力学与工程学报,2006,25(9):1765-1770(Yang Gengshe,Zhou Chunhua,Tian Yingguo,et al.Primary experimental study on moisture and heat transfer of soft rock material during its freezing and thawing[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(9):1765-1770(in Chinese))
[17]Kassner M E,Nemat-Nasser S,Suo Z,et al.New directions in mechanics[J].Mechanics of Materials,2005,37(2/3):231-259
[18]陈从新,刘秀敏,刘才华.数字图像技术在岩石细观力学研究中的应用[J].岩土力学,2010,31(S1):53-61(Chen Congxin,Liu Xiumin,Liu Caihua.Application of digital image processing to rock mesomechanics[J].Rock and Soil Mechanics,2010,31(S1):53-61(in Chinese))
[19]刘恺德,刘泉声,朱元广,等.考虑层理方向效应煤岩巴西劈裂及单轴压缩试验研究[J].岩石力学与工程学报,2013,32(2):308-316(Liu Kaide,Liu Quansheng,Zhu Yuanguang,et al.Experimental study of coal considering directivity effect of stratification plane under brazilian splitting and uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):308-316(in Chinese))
[20]包春燕,唐春安,唐世斌,等.温缩等间距表面裂纹扩展的数值模拟及其机制研究[J].岩石力学与工程学报,2014,33(3):549-557(Bao Chunyan,Tang Chun’an,Tang Shibin,et al.Numerical simulation and mechanism research of surface fracture equal-spacing subjected to cooling shrinking[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(3):549-557(in Chinese))