An Analytical Study of Failure of Transversely Isotropic Rock Discs Subjected to Various Diametrical Loading Configurations
- Z. Aliabadian (The University of New South Wales) | G. F. Zhao (Tianjin University) | A. R. Russell (The University of New South Wales)
- Document ID
- International Society for Rock Mechanics and Rock Engineering
- ISRM European Rock Mechanics Symposium - EUROCK 2017, 20-22 June, Ostrava, Czech Republic
- Publication Date
- Document Type
- Conference Paper
- 2017. Elsevier Ltd. Permission to distribute - International Society for Rock Mechanics and Rock Engineering
- Analytical solution, Analytical solution, Crack initiation, Anisotropic rocks, Analytical solution, Crack initiation, Brazilian disc, Anisotropic rocks, Brazilian disc, Anisotropic rocks, Crack initiation, Brazilian disc
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The indirect (Brazilian) tensile strength test is commonly used in rock engineering and rock mechanics. Most of the research on how to interpret Brazilian test is only valid for isotropic rock. The load may be applied to disc shaped samples through flat platens or curved jaws and the different load configurations give rise to subtle but important differences to stress distributions throughout samples during testing and at the onset of failure. To reliably obtain the tensile strength accurate stress distributions, especially at the location of the initial crack, must be determined. However, most real rocks exhibit a certain type of anisotropy known as transverse isotropy due to the presence of preferred directions of grains, beddings, microcracks or pores. This study focuses on the failure modes when transverse isotropy is present. Previous studies for transverse isotropy indicate that the exact location of the initial crack is at the disc centre. These studies, however, ignore the effect of the load contact configuration on the stress distribution. This paper overcomes this limitation and applies Amadei’s analytical solution to assess the effects of the load contact area on the stress distribution. The stress distribution is coupled with a transverse isotropy failure criterion in a mechanically consistent way to find the exact location of initial crack. It is shown that the location of the initial crack depends on the transverse isotropy orientation and load configuration.
The Brazilian test is a diametrical compression test that is used as an indirect tensile strength measurement. At first, the test was proposed by Carneiro  and Akazawa  to obtain tensile strength of concrete. In 1978, the International Society for Rock Mechanics (ISRM) officially presented Brazilian test as a standard method to indirectly determine the tensile strength of rock like materials (ISRM 2007).
Nowadays the Brazilian test is widely used to determine tensile strength of rock like materials because of its simple specimen preparation, experimental performance and data reduction [3-4]. In the test, a thin disc is diametrically compressed. The corresponding stress field throughout the specimen is highly non-uniform.
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