灰岩平板试件变形破坏过程的实验观测研究
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摘要
利用扫描电镜实时观测系统,研究了带预制割缝灰岩平板试件受单轴压缩时微裂纹的萌生、扩展和连通过程。实验所用灰岩平板试件尺寸为25 mm×13 mm×1.1 mm,试件中心预制一直径为3.0 mm的圆孔或一长轴与外载方向成不同角度(30°,45°或60°)的割缝,割缝长约6 mm,宽约1 mm。在扫描电镜的观察下,灰岩试样受到准静态单轴压缩。用照相的方法记录了试件受力产生变形和微裂纹扩展过程中的表面图像。将实验观测的微裂纹扩展结果与大理岩和砂岩中的裂纹扩展过程进行对比,发现次生裂纹的萌生部位与大理岩和砂岩中比较一致,但灰岩中的裂纹发育较单一。用NOLM程序中的低抗拉应变软化本构模型对实验结果进行了有限元模拟计算,将计算结果与实验观测结果进行对比,两者吻合较好。
Testing study is made on the mini-crack development around a prefabricated fracture in a limestone plate specimen subject to uniaxial compression. The rock used for test is limestone,and direct SEM observation is used for testing. The elastic modulus of rock specimen is about 93.7 GPa,Poisson′s ratio 0.25 and uniaxial compressive strength 201 MPa. The specimen is a plate of 25 mm×13 mm×1.1 mm in size with a prefabricated central circular or a slot about 0.6 mm wide and 6.0 mm long. The major axis of the prefabricated slot is inclined to the loading direction at 30°,45°,60°,respectively. The tests are carried out in the vacuum chamber of a SEM using a vise-type loading frame. Its loading capacity is 2 000 N and the load on the specimen is measured by the piezoelectric transducer with an accuracy of 0.5 N. The development of mini-cracks in limestone specimen under uniaxial loading is photographed and analyzed. The test results are compared with those in marble and sandstone specimens from the previous study. It is shown from the comparison that the initiation points of cracks are similar in all three rock specimens,but there are less multiple mini-cracks development in limestone specimen. Finite element computation of the mini-crack process is performed using NOLM program with a strain-softening constitutive model of low tensile resistance. The computation result represents the experimental observation fairly well. The calculated results are compared with testing data,and they are agreed well with each other.
Testing study is made on the mini-crack development around a prefabricated fracture in a limestone plate specimen subject to uniaxial compression. The rock used for test is limestone,and direct SEM observation is used for testing. The elastic modulus of rock specimen is about 93.7 GPa,Poisson′s ratio 0.25 and uniaxial compressive strength 201 MPa. The specimen is a plate of 25 mm×13 mm×1.1 mm in size with a prefabricated central circular or a slot about 0.6 mm wide and 6.0 mm long. The major axis of the prefabricated slot is inclined to the loading direction at 30°,45°,60°,respectively. The tests are carried out in the vacuum chamber of a SEM using a vise-type loading frame. Its loading capacity is 2 000 N and the load on the specimen is measured by the piezoelectric transducer with an accuracy of 0.5 N. The development of mini-cracks in limestone specimen under uniaxial loading is photographed and analyzed. The test results are compared with those in marble and sandstone specimens from the previous study. It is shown from the comparison that the initiation points of cracks are similar in all three rock specimens,but there are less multiple mini-cracks development in limestone specimen. Finite element computation of the mini-crack process is performed using NOLM program with a strain-softening constitutive model of low tensile resistance. The computation result represents the experimental observation fairly well. The calculated results are compared with testing data,and they are agreed well with each other.
引文
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11赵永红,黄杰藩,王仁.岩石微破裂发育的扫描电镜即时观测研究[J].岩石力学与工程学报,1992,11(3):284～294
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14ZhaoY,HuangJ,WangR.Development of subcracks between en echelon fractures in rock plates[J].Pageoph.1995,45(3/4):759～773
15赵永红,黄杰藩,候建军等.岩石细观破裂的实验观测研究及其对了解地震活动性的启示[J].地球物理学报,1995,38(5):627～635
16赵永红,扬振涛.含软弱夹层岩石材料损伤破坏过程的计算模拟[J].岩石力学与工程学报,2005,24(5):(待刊)
17赵永红.细砂岩裂纹周围变形破坏过程及应变场分布[J].岩土力学,2004,(待刊)
18谢和平.岩石材料的局部损伤拉破坏[J].岩石力学与工程学报,1988,7(2):147～154
19ZhaoY H.Crack pattern evolution and a fractal damage constitutive model for rock[J].Int.J.RockMech.Min.Sci.,1998,35(3):349～366
20BaudP,ReuschleT.A theoretical approach to the propagation of interacting cracks[J].GeophysJ.Int.,1997,130(2):460～468
21DengH,Nemat-NasserS.,Microcrack interaction and shear fault failure[J].Int.J. ofDamageMechanics,1994,3(1):3～37
22LavrovA,VervoortA,WeversM,et al.Experimental and numerical study of theKaiser effect in cyclicBrazilian tests with disk rotation[J].Int.J.RockMech.Min.Sci.,2002,39(3):287～302
23蔡永恩.热弹性问题的有限元方法及程序设计[M].北京:北京大学出版社,1997
24殷有泉.固体力学非线性有限元引论[M].北京:北京大学出版社,清华大学出版社,1987
25周维垣.高等岩石力学[M].北京:水利电力出版社,1990
26殷有泉.岩土介质的弹塑性本构关系[M].北京:中国铁道出版社,1988,236～267
2HoriiH,NematNasserS.Compression-induc edmicrocra ckgrow th inbritt lesolid s:axi alsplitti nga ndshe arfailure[J].J.Geophys.Res.,1985,90(B4):3105～3125
3林鹏.含裂纹与孔洞缺陷介质的脆性破坏行为[J].岩石力学与工程学报,2002,21(8):1283～1283
4LinP,LoganJ.Inter ac tio noftwoc losely spacedcr acks :aroc kmodelstudy[J].J.Geophys.Res.,1991,96(B/13):21667～21675
5黄明利,冯夏庭,王水林.多裂纹在不同岩石介质中的扩展贯通机制分析[J].岩土力学,2002,23(2):142～146
6黄凯珠,林鹏,唐春安等.双轴加载下断续预制裂纹贯通机制的研究[J].岩石力学与工程学报,2002,21(6):808??816
7W ongRHC, ChauKT.Crac kc o alescenceinarock- likeMateri alc ontainingtwocracks[J].Int.J.RockMech.Min.Sci.Geomech.Abstr.,1998,35(2):147～164
8WangR,Z haoYS,ChenY,e tal .Exper imentan dfiniteele mentsimu latio nofX-type shea r fract ur esfromacrackinmarble[J].Tectonophysics,1987,144(1/3):1 41～150
9Huan gJF, ChenG L,ZhaoYH,eta l.Ane xp eri mental studyo fthestrainf ields de velopme nt p riorto failu reofa marbleplateundercompression[J].Tectonophysics,1990,175(1/3):269～284
10夏蒙棼,柯孚久,吕永华等.理想裂纹系统中的随机扩展效应[J].中国科学,1991,21(3):276～284
11赵永红,黄杰藩,王仁.岩石微破裂发育的扫描电镜即时观测研究[J].岩石力学与工程学报,1992,11(3):284～294
12赵永红,黄杰藩,王仁.破裂带发育的SEM实验研究及其对地震前兆的启示[J].地球物理学报,1993,36(4):453～462
13ZhaoY H,HuangJ F,WangR.Real-timeSEM observations of theMicrofracturing process in rock during a compression test[J].Int.J.RockMech.Min.Sci.Geomech.Abstr.,1993,30(6):643～652
14ZhaoY,HuangJ,WangR.Development of subcracks between en echelon fractures in rock plates[J].Pageoph.1995,45(3/4):759～773
15赵永红,黄杰藩,候建军等.岩石细观破裂的实验观测研究及其对了解地震活动性的启示[J].地球物理学报,1995,38(5):627～635
16赵永红,扬振涛.含软弱夹层岩石材料损伤破坏过程的计算模拟[J].岩石力学与工程学报,2005,24(5):(待刊)
17赵永红.细砂岩裂纹周围变形破坏过程及应变场分布[J].岩土力学,2004,(待刊)
18谢和平.岩石材料的局部损伤拉破坏[J].岩石力学与工程学报,1988,7(2):147～154
19ZhaoY H.Crack pattern evolution and a fractal damage constitutive model for rock[J].Int.J.RockMech.Min.Sci.,1998,35(3):349～366
20BaudP,ReuschleT.A theoretical approach to the propagation of interacting cracks[J].GeophysJ.Int.,1997,130(2):460～468
21DengH,Nemat-NasserS.,Microcrack interaction and shear fault failure[J].Int.J. ofDamageMechanics,1994,3(1):3～37
22LavrovA,VervoortA,WeversM,et al.Experimental and numerical study of theKaiser effect in cyclicBrazilian tests with disk rotation[J].Int.J.RockMech.Min.Sci.,2002,39(3):287～302
23蔡永恩.热弹性问题的有限元方法及程序设计[M].北京:北京大学出版社,1997
24殷有泉.固体力学非线性有限元引论[M].北京:北京大学出版社,清华大学出版社,1987
25周维垣.高等岩石力学[M].北京:水利电力出版社,1990
26殷有泉.岩土介质的弹塑性本构关系[M].北京:中国铁道出版社,1988,236～267
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