In order to study the effect of loading rate on fracture behavior of dam concrete, wedge splitting tests of various loading rates (0.1, 0.01, and 0.001 mm/s) are carried out on two kinds of full-graded dam concrete notched cubes with side lengths of 300 and 450 mm, respectively. Digital image correlation and acoustic emission technique are used to measure the deformation and acoustic emission parameters of the dam concrete. Test results show that: the peak load and fracture energy of dam concrete specimens increases with the increase of loading rate. And the higher the loading rate is, the fracture of concrete shows more obvious brittleness. Influenced by the boundary effect, the CTOD increases with the increasing of loading rate, however, the length of crack decreases as loading rate increases. With the loading rate increases, the energy mutation area is more obvious, while the accumulated acoustic emission energy is affected by both the loading rate and the maximum aggregate size. The number of acoustic emission three-dimensional locating points and the shear signal decrease with the increase of loading rate, which is attributed to that the faster the loading rate is, the less sufficient the development of micro cracks in concrete is. The test results can supply experimental data to the fracture mechanics of dam concrete.
HillerborgAModéerMPeterssonPE.Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements. Cem Concr Res1976; 6(6): 773–781.
2.
BazantZPKimJKPfeifferPA.Determination of fracture properties from size effect tests. ASCE J Struct Eng1986; 112(2): 289–307.
3.
ShahSP.Size-effect method for determining fracture energy and process zone size of concrete. Mater Struct1990; 23(6): 461–465.
4.
BažantZP.Size effect in blunt fracture: concrete, rock, metal. ASCE J Eng Mech1984; 110(4): 518–535.
5.
KumarSBaraiSV.Determining double-K fracture parameters of concrete for compact tension and wedge splitting tests using weight function. Eng Fract Mech2009; 76: 935–948.
6.
GuLTianJKongX, et al. Analysis of crack resistance of dam concrete based on performance of fully graded specimens. Water Resour Hydropower Eng2019; 50(12): 178–183. (in Chinese)
7.
ZhuB.Stress level factor and safety level factor of concrete arch dam. Water Resour Hydropower Eng2000; 8: 1–3. (in Chinese)
8.
JiJWangR.Comprehensive review of strength design criteria for arch dams at home and abroad. Sichuan Water Power1992; 1: 42–49+66. (in Chinese)
9.
RosaALYuRCRuizG, et al. A loading rate dependent cohesive model for concrete fracture. Eng Fract Mech2012; 82: 195–208.
10.
Vidya SagarRRaoMVMS. An experimental study on loading rate effect on acoustic emission based b-values related to reinforced concrete fracture. Constr Build Mater2014; 70: 460–472.
11.
PetersWHRansonWFSuttonMA, et al, Application of digital correlation methods to rigid body mechanics. Opt Eng1983; 22(6): 738–742.
12.
SuttonMAWoltersWJPetersWH, et al. Determination of displacements using an improved digital correlation method. Image Vis Comput1983; 1(3): 133–139.
13.
YasmeenFand SuttonMARajanS, et al. Effect of surface normal variability on local surface strain measurements in Stereo DIC. Opt Lasers Eng2021; 138: 106373.
14.
RajanSSuttonMAWehbeR, et al. Experimental investigation of prepreg slit tape wrinkling during automated fiber placement process using Stereo DIC. Compos B Eng2019; 160: 546–557.
15.
KoohborBKidaneASuttonMA, et al. Analysis of dynamic bending test using ultra high speed DIC and the virtual fields method. Int J Impact Eng2017; 110: 299–310.
16.
YuKLeiDChenY, et al. Research on digital image correlation method of concrete wedge splitting failure. Sci Technol Eng2014; 14(15): 251–253+258. (in Chinese)
17.
PereiraEBFischerGBarrosJA.Direct assessment of tensile stress-crack opening behavior of strain hardening cementitious composites (SHCC). Cem Concr Res2012; 42(6): 834–846.
18.
GolewskiGLGilDM.Studies of fracture toughness in concretes containing fly ash and silica fume in the first 28 days of curing. Materials2021; 14(2): 319.
19.
GolewskiGL.Changes in the fracture toughness under Mode II loading of low calcium fly ash (LCFA) concrete depending on ages. Materials2020; 13(22): 5241.
20.
GolewskiGL.Validation of the favorable quantity of fly ash in concrete and analysis of crack propagation and its length – using the crack tip tracking (CTT) method – in the fracture toughness examinations under Mode II, through digital image correlation. Constr Build Mater2021; 296: 122362.
21.
GolewskiGL.Evaluation of fracture processes under shear with the use of DIC technique in fly ash concrete and accurate measurement of crack path lengths with the use of a new crack tip tracking method. Measurement2021; 181: 109632.
22.
GongNHuS.Study on acoustic emission characteristics of concrete during I – II mixed mode fracture. J Disaster Prev Mitig Eng2019; 39(1): 171–179. (in Chinese)
23.
HuangYHYangSQTianWL.Cracking process of a granite specimen that contains multiple pre-existing holes under uniaxial compression. Fatigue Fract Eng Mater Struct2019; 42(6): 1341–1356.
24.
MihashiHNomuraNNiisekiS.Influence of aggregate size on fracture process zone of concrete detected with three-dimensional acoustic emission technique. Cem Concr Res1991; 21(5): 737–744.
25.
AlamSYSalibaJLoukiliA.Fracture examination in concrete through combined digital image correlation and acoustic emission techniques. Constr Build Mater2014; 69: 232–242.
26.
DaiSLiuXNawnitK.Experimental study on the fracture process zone characteristics in concrete utilizing DIC and AE methods. Appl Sci2019; 9(7): 1346.
27.
ChenXBuJFanX, et al. Effect of loading frequency and stress level on low cycle fatigue behavior of plain concrete in direct tension. Constr Build Mater2017; 133: 367–375.
28.
ChenXBuJ.Experimental study on direct tensile behavior of concrete under various loading regimes. ACI Mater J2016; 113(4): 513–522.
29.
ChenXChenCXuL, et al. Dynamic flexural strength of concrete under high strain rates. Mag Concrete Res2017; 69(3): 109–119.
30.
ChenCFanXChenX.Experimental investigation of concrete fracture behavior with different loading rates based on acoustic emission. Constr Build Mater2020; 237: 117472.
31.
YanDLinG.Dynamic properties of concrete in direct tension. Cem Concr Res2006; 36(7): 1371–1378.
32.
WittmannFH.Size effect of fracture energy of concrete. Eng Fract Mech1990; 35(123): 107–115.
33.
UlfkjærJPKrenkSBrinckerR.Analytical model for fictitious crack propagation in concrete beams. ASCE J Eng Mech1995; 121(1): 7–15.
34.
PoliesAW.Identification of concrete fracture parameters using digital image correlation and inverse analysis. Dissertation, University of Windsor, Windsor, Canada, 2013.
35.
HuXZWittmannF.Size effect on toughness induced by crack close to free surface. Eng Fract Mech2000; 65(2–3): 209–221.
36.
HuXZDuanK.Influence of fracture process zone height on fracture energyof concrete. Cem Concr Res2004; 34(8): 1321–1330.
37.
DuanKHuXZWittmannFH.Boundary effect on concrete fracture and nonconstant fracture energy distribution. Eng Fract Mech2003; 70(16): 2257–2268.
