中心直裂纹半圆盘试样的石灰岩断裂韧度尺寸效应试验研究
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摘要
为了考察试样尺寸和预制裂缝长度对岩石断裂韧度测试值的影响,采用4种圆盘半径分别为25.0、37.5、50.0、75.0 mm,预制裂缝长度与圆盘试样半径比值(无量纲裂缝长度)在0.3～0.7范围内的中心直裂纹半圆盘石灰岩试样(NSCB)进行了三点弯曲断裂试验。结果表明:NSCB试样的破坏过程表现出明显的"脆性"破坏特征。与预制裂缝长度相比,试样尺寸对峰值载荷和载荷-位移曲线的形态影响更显著;随着试样尺寸的增加,试样的断裂韧度测试值不断增加,增加幅度随着预制裂缝长度的增加而加剧;当试样尺寸一定时,随着无量纲裂缝长度的增加,断裂韧度测试值有一定程度降低;为减小尺寸效应的影响,建议采用圆盘半径大于37.5 mm,无量纲预制裂缝长度范围在0.4～0.6内的NSCB试样测试岩石的断裂韧度。所得结果为推广NSCB试样国际建议方法及准确测试岩石的断裂韧度提供了一定的参考。
This study is aimed to investigate the effects of the specimen size and prefabricated crack length on the rock fracture toughness. Then three-point bending tests are conducted on semi-circular limestone specimens(NSCB) with four disc radii of 25.0,37.5, 50.0 and 75.0 mm, respectively. The ratio of prefabricated crack length to the radius of disc specimens(dimensionless crack length) ranged from 0.3 to 0.7. The results show that the failure process of NSCB specimens exhibits the characteristic of an obvious brittle failure. Compared with the prefabricated crack length, the specimen size has more significant influence on the peak load and the shape of load-deformation curve. As the specimen size increases, the testing values of fracture toughness increase continuously.Moreover, the increase rate increases with the length of the prefabricated crack length. For a selected-size specimen, the testing value of fracture toughness reduces with the increase of prefabricated crack length. In order to reduce the effect of size effect in the fracture toughness test, it is suggested that the radius of NSCB specimen is greater than 37.5 mm and the dimensionless prefabricated crack length is in the range of 0.4～0.6. This study provides certain references for the promotion of the international method and the accurate test of rock fracture toughness using NSCB specimens.
This study is aimed to investigate the effects of the specimen size and prefabricated crack length on the rock fracture toughness. Then three-point bending tests are conducted on semi-circular limestone specimens(NSCB) with four disc radii of 25.0,37.5, 50.0 and 75.0 mm, respectively. The ratio of prefabricated crack length to the radius of disc specimens(dimensionless crack length) ranged from 0.3 to 0.7. The results show that the failure process of NSCB specimens exhibits the characteristic of an obvious brittle failure. Compared with the prefabricated crack length, the specimen size has more significant influence on the peak load and the shape of load-deformation curve. As the specimen size increases, the testing values of fracture toughness increase continuously.Moreover, the increase rate increases with the length of the prefabricated crack length. For a selected-size specimen, the testing value of fracture toughness reduces with the increase of prefabricated crack length. In order to reduce the effect of size effect in the fracture toughness test, it is suggested that the radius of NSCB specimen is greater than 37.5 mm and the dimensionless prefabricated crack length is in the range of 0.4～0.6. This study provides certain references for the promotion of the international method and the accurate test of rock fracture toughness using NSCB specimens.
引文
[1]任利,谢和平,谢凌志,等.基于断裂力学的裂隙岩体强度分析初探[J].工程力学,2013,30(2):156-168.REN Li,XIE He-ping,XIE Ling-zhi,et al.Preliminary study on strength of cracked rock specimen based on fracture mechanics[J].Engineering Mechanics,2013,30(2):156-168.
[2]纪维伟,潘鹏志,苗书婷,等.基于数字图像相关法的两类岩石断裂特征研究[J].岩土力学,2016,37(8):2299-2305.JI Wei-wei,PAN Peng-zhi,MIAO Shu-ting,et al.Fracture characteristics of two types of rocks based on digital image correlation[J].Rock and Soil Mechanics,2016,37(8):2299-2305.
[3]郑雨天,张兴,石海鱼.岩石断裂韧度测定的研究[J].水利学报,1984(9):19-28.ZHENG Yu-tian,ZHANG Xing,SHI Hai-yu.Experimental research on fracture toughness of rock[J].Journal of Hydraulic Engineering,1984(9):19-28.
[4]吴礼舟,王启智,贾学明.用人字形切槽巴西圆盘(CCNBD)确定岩石断裂韧度及其尺度律[J].岩石力学与工程学报,2004,23(3):383-390.WU Li-zhou,WANG Qi-zhi,JIA Xue-ming.Determination of mode-I rock fracture toughness with cracked chevron notched Brazilian disc(CCNBD)and application of size effect law[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(3):383-390.
[5]华文,董世明,徐积刚.复合型加载条件下锈岩断裂韧度试验研究[J].岩土力学,2016,37(3):753-758.HUA Wen,DONG Shi-ming,XU Ji-gang.Experimental research on fracture toughness of rust stone under mixed mode loading conditions[J].Rock and Soil Mechanics,2016,37(3):753-758.
[6]郝显福,陆道辉,孙嘉,等.微扰动作用下预静载硬岩的断裂特性研究[J].黄金,2016,37(9):34-38.HAO Xian-fu,LU Dao-hui,SUN Jia,et al.Study of hard rock fracture properties with pre-static load under micro disturbance[J].Gold,2016,37(9):34-38.
[7]尹乾,靖洪文,苏海健,等.高温后花岗岩断裂特性的加载速率效应研究[J].中国矿业大学学报,2015,44(4):597-603.YIN Qian,JING Hong-wen,SU Hai-jian,et al.Loading rate effect on fracture properties of granite after high temperature[J].Journal of China University of Mining&Technology,2015,44(4):597-603.
[8]李操.温度对岩石类材料断裂性能的影响研究[J].南京工程学院学报(自然科学版),2013,11(4):39-46.LI Cao.A study of the effect of temperature on the fracture properties of rock materials[J].Journal of Nanjing Institute of Technology(Natural Science Edition),2013,11(4):39-46.
[9]张盛,王启智.用5种圆盘试件的劈裂试验确定岩石断裂韧度[J].岩土力学,2009,30(1):12-18.ZHANG Sheng,WANG Qi-zhi.Determination of rock fracture toughness by split test using five types of disc specimens[J].Rock and Soil Mechanics,2009,30(1):12-18.
[10]崔振东,刘大安,安光明,等.岩石Ⅰ型断裂韧度测试方法研究进展[J].测试技术学报,2009,23(3):189-196.CUI Zhen-dong,LIU Da-an,AN Guang-ming,et al.Research progress in mode-I fracture toughness testing methods for rocks[J].Journal of Test and Measurement Technology,2009,23(3):189-196.
[11]BAZANT Z P.Size effect[J].International Journal of Solids and Structures,2000,37(1):69-80.
[12]BAZANT Z P,KAZEMI M T.Size dependence of concrete fracture energy determined by RILEMwork-of-fracture method[J].International Journal of Fracture,1991,51(2):121-138.
[13]SHAH S P.Size-effects methods for determining fracture energy and process zone size of concrete[J].Materials and Structures,1990,23(6):461-465.
[14]崔振东,刘大安,安光明,等.V形切槽巴西圆盘法测定岩石断KIc的实验研究[J].岩土力学,2010,31(9):2743-2748.CUI Zhen-dong,LIU Da-an,AN Guang-ming,et al.Research for determining mode I rock fracture toughness KIc using cracked chevron notched brazilian disc specimne[J].Rock and Soil Mechanics,2010,31(9):2743-2748.
[15]梁利喜,何顺平,张安东.CCNBD试样测试页岩I型断裂韧性[J].西部探矿工程,2016,28(11):41-43,46.LIANG Li-xi,HE Shun-ping,ZHANG An-dong.Determination of mode-I rock fracture toughness with cracked chevron notched Brazilian disc(CCNBD)sample[J].West-China Exploration Engineering,2016,28(11):41-43,46.
[16]张盛,王启智,谢和平.岩石动态断裂韧度的尺寸效应[J].爆炸与冲击,2008,28(6):544-551.ZHANG Sheng,WANG Qi-zhi,XIE He-ping.Size effect of rock dynamic fracture toughness[J].Explosion and Shock Waves,2008,28(6):544-551.
[17]冯峰,韦重耕,王启智.用中心直裂纹平台巴西圆盘测试岩石动态断裂韧度的尺寸效应[J].工程力学,2009,26(4):167-173.FENG Feng,WEI Chong-geng,WANG Qi-zhi.Size effect for rock dynamic fracture toughness tested with cracked straight through flattened Brazilian disc[J].Engineering Mechanics,2009,26(4):167-173.
[18]ARSLAN A,INCE R.The neural network approximation to the size effect in fracture of cementitious materials[J].Engineering Fracture Mechanics,1996,54(2):249-261.
[19]TUTLUOGLU L,KELES C.Effects of geometric factors on mode I fracture toughness for modified ring tests[J].International Journal of Rock Mechanics&Mining Sciences,2012,51(1):149-161.
[20]FAKHIMI A,TAROKH A.Process zone and size effect in fracture testing of rock[J].International Journal of Rock Mechanics&Mining Sciences,2013,60(6):95-102.
[21]AYATOLLAH M R,AKBARDOOST J.Size and geometry effects on rock fracture toughness:mode Ifracture[J].Rock Mechanics&Rock Engineering,2014,47(2):677-687.
[22]张盛,王启智,梁亚磊.裂缝长度对岩石动态断裂韧度测试值影响的研究[J].岩石力学与工程学报,2009,28(8):1691-1696.ZHANG Sheng,WANG Qi-zhi,LIANG Ya-lei.Research on influence of crack length on test values of rock dynamic fracture toughness[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(8):1691-1696.
[23]ZHANG P,GAO J X,ZHU H T,et al.Effect of prefabricated crack length on fracture toughness and fracture energy of fly ash concrete reinforced by Nano-Si O2 and fibers[J].Iranian Journal of Science&Technology Transactions of Civil Engineering,2016,40(1):69-74.
[24]CHANG S H,LEE C I,JEON S.Measurement of rock fracture toughness under modes I and II and mixed-mode conditions by using disc-type specimens[J].Engineering Geology,2002,66(1):79-97.
[25]WANG Y S,HU X Z.Determination of tensile strength and fracture toughness of granite using notched three-point-bend samples[J].Rock Mechanics&Rock Engineering,2017,50(1):17-28.
[26]CHONG K P,KURUPPU M D.New specimen for fracture toughness determination for rock and other materials[J].International Journal of Fracture,1984,26(2):59-62.
[27]KURUPPU M D,OBARA Y,AYATOLLAHI M R,et al.ISRM-suggested method for determining the mode I static fracture toughness using semi-circular bend specimen[J].Rock Mechanics&Rock Engineering,2014,47(1):267-274.
[28]宫凤强,陆道辉,李夕兵,等.动力扰动下预静载硬岩断裂的增韧和减韧效应[J].岩石力学与工程学报,2014,33(9):1905-1915.GONG Feng-qiang,LU Dao-hui,LI Xi-bing,et al.Toughness increasing of decreasing effect of hard rock fracture with pre-static loading under dynamic disturbance[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(9):1905-1915.
[29]李清,郭洋,马万权,等.半圆盘构件冲击断裂特性的动态焦散线实验研究[J].振动与冲击,2016,35(9):52-58.LI Qing,GUO Yang,MA Wan-quan,et al.Dynamic caustics tests for semi-circular specimen under impact loading[J].Journal of Vibration and Shock,2016,35(9):52-58.
[30]冯若琪,朱哲明,范勇.砂岩半圆盘弯曲的复合型断裂性质及准则研究[J].四川大学学报(工程科学版),2016,48(增刊1):121-127.FENG Ruo-qi,ZHU Zhe-ming,FAN Yong.Research on mixed-mode fracture properties and criteria by using sandstone SCB specimen[J].Journal of Sichuan University(Engineering Science Edition),2016,48(Suppl.1):121-127.
[31]张盛,王启智.用变裂缝单一尺寸试样确定大理岩的断裂韧度[J].工程力学,2007,24(6):31-35.ZHANG Sheng,WANG Qi-zhi.Determination of marble fracture toughness by using variable-crack one-size specimens[J].Engineering Mechanics,2007,24(6):31-35.
[32]赵毅鑫,龚爽,姜耀东,等.基于半圆弯拉试验的煤样抗拉及断裂性能研究[J].岩石力学与工程学报,2016,35(6):1255-1264.ZHAO Yi-xin,GONG Shuang,JIANG Yao-dong,et al.Characteristics of tensile strength and fracture properties of coal based on semi-circular bending tests[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(6):1255-1264.
[2]纪维伟,潘鹏志,苗书婷,等.基于数字图像相关法的两类岩石断裂特征研究[J].岩土力学,2016,37(8):2299-2305.JI Wei-wei,PAN Peng-zhi,MIAO Shu-ting,et al.Fracture characteristics of two types of rocks based on digital image correlation[J].Rock and Soil Mechanics,2016,37(8):2299-2305.
[3]郑雨天,张兴,石海鱼.岩石断裂韧度测定的研究[J].水利学报,1984(9):19-28.ZHENG Yu-tian,ZHANG Xing,SHI Hai-yu.Experimental research on fracture toughness of rock[J].Journal of Hydraulic Engineering,1984(9):19-28.
[4]吴礼舟,王启智,贾学明.用人字形切槽巴西圆盘(CCNBD)确定岩石断裂韧度及其尺度律[J].岩石力学与工程学报,2004,23(3):383-390.WU Li-zhou,WANG Qi-zhi,JIA Xue-ming.Determination of mode-I rock fracture toughness with cracked chevron notched Brazilian disc(CCNBD)and application of size effect law[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(3):383-390.
[5]华文,董世明,徐积刚.复合型加载条件下锈岩断裂韧度试验研究[J].岩土力学,2016,37(3):753-758.HUA Wen,DONG Shi-ming,XU Ji-gang.Experimental research on fracture toughness of rust stone under mixed mode loading conditions[J].Rock and Soil Mechanics,2016,37(3):753-758.
[6]郝显福,陆道辉,孙嘉,等.微扰动作用下预静载硬岩的断裂特性研究[J].黄金,2016,37(9):34-38.HAO Xian-fu,LU Dao-hui,SUN Jia,et al.Study of hard rock fracture properties with pre-static load under micro disturbance[J].Gold,2016,37(9):34-38.
[7]尹乾,靖洪文,苏海健,等.高温后花岗岩断裂特性的加载速率效应研究[J].中国矿业大学学报,2015,44(4):597-603.YIN Qian,JING Hong-wen,SU Hai-jian,et al.Loading rate effect on fracture properties of granite after high temperature[J].Journal of China University of Mining&Technology,2015,44(4):597-603.
[8]李操.温度对岩石类材料断裂性能的影响研究[J].南京工程学院学报(自然科学版),2013,11(4):39-46.LI Cao.A study of the effect of temperature on the fracture properties of rock materials[J].Journal of Nanjing Institute of Technology(Natural Science Edition),2013,11(4):39-46.
[9]张盛,王启智.用5种圆盘试件的劈裂试验确定岩石断裂韧度[J].岩土力学,2009,30(1):12-18.ZHANG Sheng,WANG Qi-zhi.Determination of rock fracture toughness by split test using five types of disc specimens[J].Rock and Soil Mechanics,2009,30(1):12-18.
[10]崔振东,刘大安,安光明,等.岩石Ⅰ型断裂韧度测试方法研究进展[J].测试技术学报,2009,23(3):189-196.CUI Zhen-dong,LIU Da-an,AN Guang-ming,et al.Research progress in mode-I fracture toughness testing methods for rocks[J].Journal of Test and Measurement Technology,2009,23(3):189-196.
[11]BAZANT Z P.Size effect[J].International Journal of Solids and Structures,2000,37(1):69-80.
[12]BAZANT Z P,KAZEMI M T.Size dependence of concrete fracture energy determined by RILEMwork-of-fracture method[J].International Journal of Fracture,1991,51(2):121-138.
[13]SHAH S P.Size-effects methods for determining fracture energy and process zone size of concrete[J].Materials and Structures,1990,23(6):461-465.
[14]崔振东,刘大安,安光明,等.V形切槽巴西圆盘法测定岩石断KIc的实验研究[J].岩土力学,2010,31(9):2743-2748.CUI Zhen-dong,LIU Da-an,AN Guang-ming,et al.Research for determining mode I rock fracture toughness KIc using cracked chevron notched brazilian disc specimne[J].Rock and Soil Mechanics,2010,31(9):2743-2748.
[15]梁利喜,何顺平,张安东.CCNBD试样测试页岩I型断裂韧性[J].西部探矿工程,2016,28(11):41-43,46.LIANG Li-xi,HE Shun-ping,ZHANG An-dong.Determination of mode-I rock fracture toughness with cracked chevron notched Brazilian disc(CCNBD)sample[J].West-China Exploration Engineering,2016,28(11):41-43,46.
[16]张盛,王启智,谢和平.岩石动态断裂韧度的尺寸效应[J].爆炸与冲击,2008,28(6):544-551.ZHANG Sheng,WANG Qi-zhi,XIE He-ping.Size effect of rock dynamic fracture toughness[J].Explosion and Shock Waves,2008,28(6):544-551.
[17]冯峰,韦重耕,王启智.用中心直裂纹平台巴西圆盘测试岩石动态断裂韧度的尺寸效应[J].工程力学,2009,26(4):167-173.FENG Feng,WEI Chong-geng,WANG Qi-zhi.Size effect for rock dynamic fracture toughness tested with cracked straight through flattened Brazilian disc[J].Engineering Mechanics,2009,26(4):167-173.
[18]ARSLAN A,INCE R.The neural network approximation to the size effect in fracture of cementitious materials[J].Engineering Fracture Mechanics,1996,54(2):249-261.
[19]TUTLUOGLU L,KELES C.Effects of geometric factors on mode I fracture toughness for modified ring tests[J].International Journal of Rock Mechanics&Mining Sciences,2012,51(1):149-161.
[20]FAKHIMI A,TAROKH A.Process zone and size effect in fracture testing of rock[J].International Journal of Rock Mechanics&Mining Sciences,2013,60(6):95-102.
[21]AYATOLLAH M R,AKBARDOOST J.Size and geometry effects on rock fracture toughness:mode Ifracture[J].Rock Mechanics&Rock Engineering,2014,47(2):677-687.
[22]张盛,王启智,梁亚磊.裂缝长度对岩石动态断裂韧度测试值影响的研究[J].岩石力学与工程学报,2009,28(8):1691-1696.ZHANG Sheng,WANG Qi-zhi,LIANG Ya-lei.Research on influence of crack length on test values of rock dynamic fracture toughness[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(8):1691-1696.
[23]ZHANG P,GAO J X,ZHU H T,et al.Effect of prefabricated crack length on fracture toughness and fracture energy of fly ash concrete reinforced by Nano-Si O2 and fibers[J].Iranian Journal of Science&Technology Transactions of Civil Engineering,2016,40(1):69-74.
[24]CHANG S H,LEE C I,JEON S.Measurement of rock fracture toughness under modes I and II and mixed-mode conditions by using disc-type specimens[J].Engineering Geology,2002,66(1):79-97.
[25]WANG Y S,HU X Z.Determination of tensile strength and fracture toughness of granite using notched three-point-bend samples[J].Rock Mechanics&Rock Engineering,2017,50(1):17-28.
[26]CHONG K P,KURUPPU M D.New specimen for fracture toughness determination for rock and other materials[J].International Journal of Fracture,1984,26(2):59-62.
[27]KURUPPU M D,OBARA Y,AYATOLLAHI M R,et al.ISRM-suggested method for determining the mode I static fracture toughness using semi-circular bend specimen[J].Rock Mechanics&Rock Engineering,2014,47(1):267-274.
[28]宫凤强,陆道辉,李夕兵,等.动力扰动下预静载硬岩断裂的增韧和减韧效应[J].岩石力学与工程学报,2014,33(9):1905-1915.GONG Feng-qiang,LU Dao-hui,LI Xi-bing,et al.Toughness increasing of decreasing effect of hard rock fracture with pre-static loading under dynamic disturbance[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(9):1905-1915.
[29]李清,郭洋,马万权,等.半圆盘构件冲击断裂特性的动态焦散线实验研究[J].振动与冲击,2016,35(9):52-58.LI Qing,GUO Yang,MA Wan-quan,et al.Dynamic caustics tests for semi-circular specimen under impact loading[J].Journal of Vibration and Shock,2016,35(9):52-58.
[30]冯若琪,朱哲明,范勇.砂岩半圆盘弯曲的复合型断裂性质及准则研究[J].四川大学学报(工程科学版),2016,48(增刊1):121-127.FENG Ruo-qi,ZHU Zhe-ming,FAN Yong.Research on mixed-mode fracture properties and criteria by using sandstone SCB specimen[J].Journal of Sichuan University(Engineering Science Edition),2016,48(Suppl.1):121-127.
[31]张盛,王启智.用变裂缝单一尺寸试样确定大理岩的断裂韧度[J].工程力学,2007,24(6):31-35.ZHANG Sheng,WANG Qi-zhi.Determination of marble fracture toughness by using variable-crack one-size specimens[J].Engineering Mechanics,2007,24(6):31-35.
[32]赵毅鑫,龚爽,姜耀东,等.基于半圆弯拉试验的煤样抗拉及断裂性能研究[J].岩石力学与工程学报,2016,35(6):1255-1264.ZHAO Yi-xin,GONG Shuang,JIANG Yao-dong,et al.Characteristics of tensile strength and fracture properties of coal based on semi-circular bending tests[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(6):1255-1264.