岩石材料内部特征尺度对裂纹扩展机制的影响
|
摘要
为考察岩石材料细观结构特征对于裂纹扩展机制的影响,首先借助偏光显微镜和SEM观测了3类岩石材料中材料内部组织结构,分析了各自非均质程度和晶粒大小关系。之后,对3类岩石的带I型初始裂纹的3点弯曲试样进行了落重冲击试验,同时采用高速摄影获得了不同裂纹速度下的裂纹扩展形态。将这些结果对照分析,研究了3类岩石中裂纹扩展过程与各自材料组织结构的非均质程度和晶粒大小的关系,得出初步结论:组织结构内部特征尺度越大,动态裂纹所能达到的终极速度就相对越小。反之亦然。
In order to find how the mesostructure character of rock influences the crack propagation, the heterogeneity degree, grain size in limestone, marble and granite gneiss samples were examined respectively by means of scanning electronic microscope(SEM) and polarizing microscope. Then, the three-point bending samples with an pre-existing mode I crack were impacted by drop-weight and the cracking modes of above-mentioned three types of rocks were captured by high speed photography. By contrast, there is largest microcracking area ahead the crack tip in the granite gneiss samples with the highest heterogeneity, so is the lowest dimensionless ultimate crack velocity during the dynamic fracture process. On the contrary, since the lowest heterogeneity of the limestone samples, the smallest microcracking zone and highest dimensionless crack velocity were obtained. In this regard, there should be an internal characteristic length scale that domains the ultimate crack speed in rocks: the larger length scale is, the lower crack velocity limit would be.
In order to find how the mesostructure character of rock influences the crack propagation, the heterogeneity degree, grain size in limestone, marble and granite gneiss samples were examined respectively by means of scanning electronic microscope(SEM) and polarizing microscope. Then, the three-point bending samples with an pre-existing mode I crack were impacted by drop-weight and the cracking modes of above-mentioned three types of rocks were captured by high speed photography. By contrast, there is largest microcracking area ahead the crack tip in the granite gneiss samples with the highest heterogeneity, so is the lowest dimensionless ultimate crack velocity during the dynamic fracture process. On the contrary, since the lowest heterogeneity of the limestone samples, the smallest microcracking zone and highest dimensionless crack velocity were obtained. In this regard, there should be an internal characteristic length scale that domains the ultimate crack speed in rocks: the larger length scale is, the lower crack velocity limit would be.
引文
[1]郑哲敏.连续介质力学与断裂[J].力学进展,1982,12(2):133-140.ZHENG Ze-min.Continuum mechanics and fracture[J].Advances in Mechanics,1982,12(2):133-140.
[2]FINEBERG M MARDER.Instability in dynamic fracture[J].Physical Reports,1999,313:1-108.
[3]SHARON E,FINEBERG J.Universal features of the micro-branching instability in dynamic fracture[J].Philosophical Magazine B,1998,78:243-251.
[4]SHARON E,FINEBERG J.Microbranching instability and the dynamic fracture of brittle materials[J].Physics Review B,1996,54(10):7128-7139.
[5]FINEBERG J,GROSS S,MARDER M,et al.Instabilityin the propagation of fast cracks[J].Physics Review B,1992,(45):5146-5154.
[6]RAVI-CHANDAR K,YANG B.On the role of microcracks in the dynamic fracture of brittle materials[J].Journal of the Mechanics and Physics of Solids,1997,(45):535-563.
[7]苏先基,励争.固体力学动态测试技术[M].北京:高等教育出版社,1997.
[8]刘彩平,段庆全.焦散线法对岩石类介质的适用性研究[J].金属矿山,2009,(7):143-146.LIU Cai-ping,DUAN Qing-quan.Study on the applicability of caustics to rock type media[J].Metal Mine,2009,(7):143-146.
[9]DALLY J W.Dynamic photoelastic studies of fracture[J].Experimental Mechanics,1979,19:349-361.
[10]GAO H J.Surface roughening and branching instabilities in dynamic fracture[J].Journal the of Mechanics and Physics of Solids,1993,41:457-486.
[11]B K阿特金森.岩石断裂力学[M].尹祥础,修济刚,尹灿,等译.北京:地震出版社,1992.
[12]BUEHLER M J,ABRAHAM F F,HUA-JIAN GAO.Hyperelasticity governs dynamic fracture at a critical length scale[J].Nature,2003,(426):141-146.
[13]GILMAN J J,KNUDSEN C,WALSH W P.Cleavage cracks and dislocations in LiF crystals[J].Journal of Applied Physics,1958,(6):601-607.
[14]FIELD J E.Brittle fracture:its study and application[J].Contemporary Physics,1971,(12):1-31.
[15]HULL D,BEARDMORE P.Velocity of propagation of cleavage cracks in tungsten[J].International Journal of Fracture Mechanics,1966,(2):468-487.
[16]WASHABAUGH P D,KNAUSS W G.A reconciliation of dynamic crack velocity and Rayleigh wave speed in isotropicbrittle solids[J].International Journal of Fracture Mechanics,1994,(65):97-114.
[17]ROSAKIS A J,SAMUDRALA O,COKER D.Cracks faster than the shear wave speed[J].Science,1999,284:1337-1340.
[2]FINEBERG M MARDER.Instability in dynamic fracture[J].Physical Reports,1999,313:1-108.
[3]SHARON E,FINEBERG J.Universal features of the micro-branching instability in dynamic fracture[J].Philosophical Magazine B,1998,78:243-251.
[4]SHARON E,FINEBERG J.Microbranching instability and the dynamic fracture of brittle materials[J].Physics Review B,1996,54(10):7128-7139.
[5]FINEBERG J,GROSS S,MARDER M,et al.Instabilityin the propagation of fast cracks[J].Physics Review B,1992,(45):5146-5154.
[6]RAVI-CHANDAR K,YANG B.On the role of microcracks in the dynamic fracture of brittle materials[J].Journal of the Mechanics and Physics of Solids,1997,(45):535-563.
[7]苏先基,励争.固体力学动态测试技术[M].北京:高等教育出版社,1997.
[8]刘彩平,段庆全.焦散线法对岩石类介质的适用性研究[J].金属矿山,2009,(7):143-146.LIU Cai-ping,DUAN Qing-quan.Study on the applicability of caustics to rock type media[J].Metal Mine,2009,(7):143-146.
[9]DALLY J W.Dynamic photoelastic studies of fracture[J].Experimental Mechanics,1979,19:349-361.
[10]GAO H J.Surface roughening and branching instabilities in dynamic fracture[J].Journal the of Mechanics and Physics of Solids,1993,41:457-486.
[11]B K阿特金森.岩石断裂力学[M].尹祥础,修济刚,尹灿,等译.北京:地震出版社,1992.
[12]BUEHLER M J,ABRAHAM F F,HUA-JIAN GAO.Hyperelasticity governs dynamic fracture at a critical length scale[J].Nature,2003,(426):141-146.
[13]GILMAN J J,KNUDSEN C,WALSH W P.Cleavage cracks and dislocations in LiF crystals[J].Journal of Applied Physics,1958,(6):601-607.
[14]FIELD J E.Brittle fracture:its study and application[J].Contemporary Physics,1971,(12):1-31.
[15]HULL D,BEARDMORE P.Velocity of propagation of cleavage cracks in tungsten[J].International Journal of Fracture Mechanics,1966,(2):468-487.
[16]WASHABAUGH P D,KNAUSS W G.A reconciliation of dynamic crack velocity and Rayleigh wave speed in isotropicbrittle solids[J].International Journal of Fracture Mechanics,1994,(65):97-114.
[17]ROSAKIS A J,SAMUDRALA O,COKER D.Cracks faster than the shear wave speed[J].Science,1999,284:1337-1340.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心