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Abstract Because the Brazilian disc tensile strength formula is the analytic solution based on elastic mechanics plane problems，the results calculated by this formula are very different with the direct tension test results. Based on this，splitting tensile test on more than 100 sandstone disc specimens with different thickness-to-diameter ratios are conducted. The test results show that the tensile strength increases gradually with the decreasing thickness- to-diameter ratio；when the thickness-to-diameter ratio is less than 0.3，the tensile strength gradually increases and tends to a relatively stable value；and the change curve can be better simulated with cubic function. In order to fully grasp the effect of thickness-to-diameter ratio on tensile strength，3D finite element models with different thickness-to-diameter ratios are established especially；and the distribution law of equivalent stress on disc central axis is studied in detail. The study results show that the maximum tensile stress on central axis appears in the center of the specimen end face；and the larger the specimen thickness-to-diameter ratio is，the greater the tensile stress in the center of disc end face is. The first fracture starting point is in the center of end face not in the internal center point；and the 3D finite element calculation results can provide a favorable evidence for the distribution law of tensile strength accurately. According to the multivariate linear regression of the 3D finite element calculation results，a modified formula of the Brazilian disc splitting strength considering the thickness-to- diameter ratio is given；and the modified formula has better applicability. The research results provide favorable evidence for testing tensile strength of rock accurately.
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Received: 08 October 2011
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2012, Vol. 31 
