Abstract
Based on the two-dimensional elasticity theory, this study established a mechanical model under chordally opposing distributed compressive loads, in order to perfect the theoretical foundation of the flattened Brazilian splitting test used for measuring the indirect tensile strength of rocks. The stress superposition method was used to obtain the approximate analytic solutions of stress components inside the flattened Brazilian disk. These analytic solutions were then verified through a comparison with the numerical results of the finite element method (FEM). Based on the theoretical derivation, this research carried out a contrastive study on the effect of the flattened loading angles on the stress value and stress concentration degree inside the disk. The results showed that the stress concentration degree near the loading point and the ratio of compressive/tensile stress inside the disk dramatically decreased as the flattened loading angle increased, avoiding the crushing failure near-loading point of Brazilian disk specimens. However, only the tensile stress value and the tensile region were slightly reduced with the increase of the flattened loading angle. Furthermore, this study found that the optimal flattened loading angle was 20°–30°; flattened load angles that were too large or too small made it difficult to guarantee the central tensile splitting failure principle of the Brazilian splitting test. According to the Griffith strength failure criterion, the calculative formula of the indirect tensile strength of rocks was derived theoretically. This study obtained a theoretical indirect tensile strength that closely coincided with existing and experimental results. Finally, this paper simulated the fracture evolution process of rocks under different loading angles through the use of the finite element numerical software ANSYS. The modeling results showed that the Flattened Brazilian Splitting Test using the optimal loading angle could guarantee the tensile splitting failure initiated by a central crack.
Similar content being viewed by others
Abbreviations
- FEM:
-
Finite element method
- ISRM:
-
International Society for Rock Mechanics
- SBT:
-
Standard Brazilian test
- SBD:
-
Standard Brazilian disk
- FBST:
-
Flattened Brazilian splitting test
- FBD:
-
Flattened Brazilian disk
- DEM:
-
Discrete element method
- A, B, A’, B’, M, N :
-
Points in the flattened Brazilian disk
- A i , B i and C i (i = 1, 2, 3 and 4):
-
Variables in specific equations
- b :
-
Half of the flattened width (m)
- dA :
-
Infinitesimal area (m2)
- dF :
-
Infinitesimal force (N)
- ds :
-
Infinitesimal length (m)
- E:
-
Elastic modulus (Pa)
- n :
-
Normal line at point M on the disk
- P :
-
Experimental load (N)
- q :
-
Distributed load (Pa)
- R :
-
Radius of the flattened Brazilian disk (m)
- r 1 :
-
Distance between point M and action point of infinitesimal force in the top semi-infinite plane (m)
- r 2 :
-
Distance between point M and action point of infinitesimal force in the bottom semi-infinite plane (m)
- S :
-
Distance between central point and action point of infinitesimal force (m)
- t :
-
Thickness of the flattened Brazilian disk (m)
- 2α :
-
Loading angle of flattened Brazilian disk (rad)
- θ 1 :
-
Included angle between the direction of radial stress and vertical direction in the top semi-infinite plane (rad)
- θ 2 :
-
Included angle between the direction of radial stress and vertical direction in the bottom semi-infinite plane (rad)
- ∆:
-
Triangle symbol
- σ G :
-
Griffith equivalent stress (Pa)
- σ T :
-
Tensile strength of the rock (Pa)
- σ 1 , σ 2 , σ 3 :
-
Maximum, intermediate and minimum principal stresses of the disk (Pa)
- σ n :
-
Normal stress component under the polar coordinate (Pa)
- σ r :
-
Radial stress component under the polar coordinate (Pa)
- σ τ :
-
Tangential stress component under the polar coordinate (Pa)
- σ x :
-
X-direction stress component under the cartesian coordinates (Pa)
- σ y :
-
Y-direction stress component under the cartesian coordinates (Pa)
- τ xy :
-
Shear stress component under the cartesian coordinates (Pa)
- τ :
-
Tangential line at point M on the disk
- d :
-
Differential operator
- ∫ :
-
Integral operator
References
Erarslan N, Williams DJ (2012) Experimental, numerical and analytical studies on tensile strength of rocks. Int J Rock Mech Min Sci 49:21–30
Erarslan N, Liang ZZ, Williams DJ (2012) Experimental and numerical studies on determination of indirect tensile strength of rocks. Rock Mech Rock Eng 45(5):739–751
Griffith A (1921) The Phenomena of Rupture and Flow in Solids. Philos Trans R Soc London A Contain Papers Math Phys Character 221:163–198
Hong J, Tsai C, Dong P (1998) Assessment of numerical procedures for residual stress analysis of multipass welds. Weld J 77:372s–382s
ISRM (1978) Suggested methods for determining tensile strength of rock materials. Int J Rock Mech Min Sci Geomech Abstr 15(3):99–103
Kwon OH, Jenkins MG (2002) Mechanical behavior and numerical estimation of fracture resistance of a SCS6 fiber reinforced reaction bonded S13N4 continuous fiber ceramic composite. KSME Int J 16(9):1093–1101
Lu Y, Yang S, Chen L, Lei J (2011) Mechanism of the spatial distribution and migration of the strong earthquakes in China inferred from numerical simulation. J Asian Earth Sci 40(4):990–1001
Ma C-C, Hung K-M (2008) Exact full-field analysis of strain and displacement for circular disks subjected to partially distributed compressions. Int J Mech Sci 50(2):275–292
Markides CF, Kourkoulis S (2012) The stress field in a standardized Brazilian disc: the influence of the loading type acting on the actual contact length. Rock Mech Rock Eng 45(2):145–158
Markides CF, Pazis D, Kourkoulis S (2010) Closed full-field solutions for stresses and displacements in the Brazilian disk under distributed radial load. Int J Rock Mech Min Sci 47(2):227–237
Meng J-J, Cao P, Zhang K, Tan P (2013) Brazil split test of flattened disk and rock tensile strength using particle flow code. J Cent South Univ (Science and Technology) 44(6):2454–2499
Pu H, Huang Y-G, Chen R-H (2011) Mechanical analysis for X-O type fracture morphology of stope roof. J China Univ Min Technol 6(40):835–840
Satoch Y (1987) Position and load of failure in Brazilian test a numerical analysis by Griffith criterion. J Soc Mater Sci Jpn 36(410):1219–1224
Van Cauwelaert F, Eckmann B (1994) Indirect tensile test applied to anisotropic materials. Mater Struct 27(1):54–60
Wang Q-Z, Jia X-M (2002) Determination of elastic modulus tensile strength and fracture toughness of brittle rocks by using flattened Brazilian disk specimen—part I: analytical and numerical results. Chin J Rock Mech Eng 21(9):1285–1289
Wang Q-Z, Wu L-Z (2004) Determination of elastic modulus tensile strength and fracture toughness of brittle rocks by using flattened Brazilian disk specimen—part II: analytical and numerical results. Chin J Rock Mech Eng 23(2):199–204
Wang Q-Z, Xing L (1999) Determination of fracture toughness K IC by using the flattened Brazilian disk specimen for rocks. Eng Fract Mech 64(2):193–201
Wang QZ, Jia XM, Kou SQ, Zhang ZX, Lindqvist PA (2004) The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks: analytical and numerical results. Int J Rock Mech Min Sci 41(2):245–253
Xu Z-L (2006) Elasticity, 4th Edn. Higher Education Press, Beijing, pp 54–85
Ye J, Wu F, Sun J (2009) Estimation of the tensile elastic modulus using Brazilian disc by applying diametrically opposed concentrated loads. Int J Rock Mech Min Sci 46(3):568–576
You M-Q, Su C-D (2004a) Experimental study on split test with flattened disk and tensile strength of rock. Chin J Rock Mech Eng 23(18):3106–3112
You M-Q, Su C-D (2004b) Split test of flattened rock disk and related theory. Chin J Rock Mech Eng 23(1):170–174
Yu Y, Xu Y-L (2006) Method to determine tensile of rock using flattened Brazilian disk. Chin J Rock Mech Eng 25(7):1457–1462
Yu Q-L, Tang C-A, Yang T-H, Tang S-B, Liu H-L (2008) Numerical analysis of influence of central angle of flats on tensile strength of granite in split test with flattened disk. Rock Soil Mech 29(12):3251–3255
Yu Y, Zhang J, Zhang J (2009) A modified Brazilian disk tension test. Int J Rock Mech Min Sci 46(2):421–425
Acknowledgments
This work was supported by the National 973 Programs (2014CB046905), the National Natural Science Foundation of China (Grant No. 51274191, 51404245 and 51204159), the Doctoral Fund of Ministry of Education of China (20130095110018), the China Postdoctoral Science Foundation (2014M551699) and the Fundamental Research Funds for the Central Universities (2014QNB42).The authors also thank two anonymous referees for their careful reading of this paper and valuable suggestions.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Huang, Y.G., Wang, L.G., Lu, Y.L. et al. Semi-analytical and Numerical Studies on the Flattened Brazilian Splitting Test Used for Measuring the Indirect Tensile Strength of Rocks. Rock Mech Rock Eng 48, 1849–1866 (2015). https://doi.org/10.1007/s00603-014-0676-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00603-014-0676-8