龄期对碾压混凝土双K断裂参数影响的试验研究
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摘要
为了研究龄期对碾压混凝土双K断裂参数的影响,制作了龄期为28,60,90 d共18个楔入劈拉碾压混凝土试件并进行了断裂试验,结合双K断裂参数公式,得到了不同龄期试件的有效裂缝长度、起裂断裂韧度和失稳断裂韧度等断裂参数,并分析了龄期对碾压混凝土断裂性能的影响。试验结果表明:起裂荷载和失稳荷载均随龄期的增大而增大,且起裂和失稳荷载的比值趋于稳定,伴随着龄期的增加,起裂荷载占失稳荷载的比重越来越大;龄期从28 d增加到90 d,起裂和失稳断裂韧度分别增加了0.216 0 MPa·m1/2和0.292 2 MPa·m1/2,起裂和失稳断裂韧度的比值基本在0.5～0.6;有效裂纹长度随龄期的增大而减小,相同尺寸下,龄期越小,裂缝亚临界扩展量越大,试件的韧性越好。
The influence of age on Double-K fracture parameters of roller-compacted concrete( RCC) was investigated via fracture test on eighteen RCC wedge splitting specimens at different ages( 28 d,60 d,and 90 d). The effective crack length,initial fracture toughness and unstable fracture toughness of the RCC specimens of different ages were acquired. Results revealed that with the growth of age,the critical pressure for initial cracking and critical pressure for instability both expanded,and the ratio of critical pressure for initial cracking to critical pressure for instability also increased. With the age increasing from 28 d to 90 d,initial cracking toughness Kini ICand unstable cracking toughness Kun 2 ICclimbed by 0.216 0 MPa·m1/2 and 0.292 2 MPa·m1/,respectively; the ratio of Kini ICto Kun ICmaintained between 0. 5 and 0. 6 in general. Effective critical cracking length and subcritical crack extension both changed in a negative relation with age,implying that smaller age results in better toughness of specimens.
The influence of age on Double-K fracture parameters of roller-compacted concrete( RCC) was investigated via fracture test on eighteen RCC wedge splitting specimens at different ages( 28 d,60 d,and 90 d). The effective crack length,initial fracture toughness and unstable fracture toughness of the RCC specimens of different ages were acquired. Results revealed that with the growth of age,the critical pressure for initial cracking and critical pressure for instability both expanded,and the ratio of critical pressure for initial cracking to critical pressure for instability also increased. With the age increasing from 28 d to 90 d,initial cracking toughness Kini ICand unstable cracking toughness Kun 2 ICclimbed by 0.216 0 MPa·m1/2 and 0.292 2 MPa·m1/,respectively; the ratio of Kini ICto Kun ICmaintained between 0. 5 and 0. 6 in general. Effective critical cracking length and subcritical crack extension both changed in a negative relation with age,implying that smaller age results in better toughness of specimens.
引文
[1]胡少伟,谢建锋,喻江.不同初始缝高比楔入劈拉试件断裂试验研究[J].长江科学院院报,2015,32(2):114-118.
[2]张国辉,李宗利,聂抗义,等.不同含水率混凝土断裂韧度试验研究[J].水力发电学报,2016,35(2):109-116.
[3]胡少伟,胡亮.混凝土试件四点加载剪切断裂试验研究[J].长江科学院院报,2014,31(9):99-104.
[4]陈晋.非标准楔入劈拉试件研究混凝土的断裂参数[D].大连:大连理工大学,2009.
[5]张小刚,王学志,陈意勤,等.缝高比及尺寸对碾压混凝土失稳断裂的影响[J].深圳大学学报(理工版),2011,28(2):125-130.
[6]赵超.不同再生粗骨料掺量碾压再生混凝土楔入劈拉试验研究[J].结构工程师,2015,31(1):132-136.
[7]LIU C,ZHANG H,LN.Influence of Different Sizes of Concrete and Roller Compacted Concrete on Double-KFracture Parameters[J].2016,10(35):500-508.
[8]王学志,毕重,张小刚,等.碾压混凝土断裂韧度尺寸效应的试验研究[J].武汉理工大学学报,2007,29(6):54-57.
[9]BAˇZANT Z P,OH B H.Crack Band Theory for Fracture of Concrete[J].Matériaux et Construction,1983,16(3):155-177.
[10]HILLERBORG A,MODER M,PETERSSON P E.A-nalysis of Crack Formation and Crack Growth in Concrete by Means of Fracture Mechanics and Finite Elements[J].Cement and Concrete Research,1976,6(6):773-781.
[11]JENQ Y S,SHAH S P.Two Parameters Fracture Model for Concrete[J].Journal of Engineering Mechanics,ASCE,1985,111(10):1227-1241.
[12]KARIHALOO B L,NALLATHAMBI P.Effective Cracks Model for the Determination of Fracture Toughness(KIce)of Concrete[J].Engineering Fracture Mechanics,1990,35(1/3):637-645.
[13]BAˇZANT Z P,KAZEMI M T.Determination of Fracture Energy,Process Zone Length and Brittleness Number from Size Effect,with Application to Rock and Concrete[J].International Journal of Fracture,1990,44(2):111-131.
[14]XU S,REINHARDT H W.Determination of Double-K,Criterion for Crack Propagation in Quasi-brittle Fracture,Part II:Analytical Evaluating and Practical Measuring Methods for Three-point Bending Notched Beams[J].International Journal of Fracture,1999,98(2):151-177.
[15]徐世烺.混凝土断裂力学[M].北京:科学出版社,2011:232.
[16]DL/T 5332-2005,水工混凝土断裂试验规程[S].北京:中国电力出版社,2006.
[17]胡少伟,范向前,陆俊.强度等级对混凝土双K断裂参数的影响[J].水电能源科学,2012,(9):77-81.
[2]张国辉,李宗利,聂抗义,等.不同含水率混凝土断裂韧度试验研究[J].水力发电学报,2016,35(2):109-116.
[3]胡少伟,胡亮.混凝土试件四点加载剪切断裂试验研究[J].长江科学院院报,2014,31(9):99-104.
[4]陈晋.非标准楔入劈拉试件研究混凝土的断裂参数[D].大连:大连理工大学,2009.
[5]张小刚,王学志,陈意勤,等.缝高比及尺寸对碾压混凝土失稳断裂的影响[J].深圳大学学报(理工版),2011,28(2):125-130.
[6]赵超.不同再生粗骨料掺量碾压再生混凝土楔入劈拉试验研究[J].结构工程师,2015,31(1):132-136.
[7]LIU C,ZHANG H,LN.Influence of Different Sizes of Concrete and Roller Compacted Concrete on Double-KFracture Parameters[J].2016,10(35):500-508.
[8]王学志,毕重,张小刚,等.碾压混凝土断裂韧度尺寸效应的试验研究[J].武汉理工大学学报,2007,29(6):54-57.
[9]BAˇZANT Z P,OH B H.Crack Band Theory for Fracture of Concrete[J].Matériaux et Construction,1983,16(3):155-177.
[10]HILLERBORG A,MODER M,PETERSSON P E.A-nalysis of Crack Formation and Crack Growth in Concrete by Means of Fracture Mechanics and Finite Elements[J].Cement and Concrete Research,1976,6(6):773-781.
[11]JENQ Y S,SHAH S P.Two Parameters Fracture Model for Concrete[J].Journal of Engineering Mechanics,ASCE,1985,111(10):1227-1241.
[12]KARIHALOO B L,NALLATHAMBI P.Effective Cracks Model for the Determination of Fracture Toughness(KIce)of Concrete[J].Engineering Fracture Mechanics,1990,35(1/3):637-645.
[13]BAˇZANT Z P,KAZEMI M T.Determination of Fracture Energy,Process Zone Length and Brittleness Number from Size Effect,with Application to Rock and Concrete[J].International Journal of Fracture,1990,44(2):111-131.
[14]XU S,REINHARDT H W.Determination of Double-K,Criterion for Crack Propagation in Quasi-brittle Fracture,Part II:Analytical Evaluating and Practical Measuring Methods for Three-point Bending Notched Beams[J].International Journal of Fracture,1999,98(2):151-177.
[15]徐世烺.混凝土断裂力学[M].北京:科学出版社,2011:232.
[16]DL/T 5332-2005,水工混凝土断裂试验规程[S].北京:中国电力出版社,2006.
[17]胡少伟,范向前,陆俊.强度等级对混凝土双K断裂参数的影响[J].水电能源科学,2012,(9):77-81.