Research Article

Determining Tensile Strength of Rock by the Direct Tensile, Brazilian Splitting, and Three-Point Bending Methods: A Comparative Study

Table 6

Results of direct tensile test of marbles.

Sample no.Diameter, d (mm)Height, h (mm)Tensile failure area, At (mm2)Failure load, P (kN)Tensile strength, σt (MPa)Tensile modulus, Et (GPa)Modulus 2, E2 (GPa)Remarks

149.17103.4411426.585.7622.5822.24
248.75103.2811797.096.0239.15
349.21103.9913557.045.2028.7828.45
449.13103.3012487.025.6232.00
549.36102.1212327.456.0532.87
649.18101.2212086.735.5833.03

Description: (1) elastic modulus Et is the ratio of tensile stress to tensile strain in the middle of the rock sample, which is the tensile elastic modulus; (2) elastic modulus E2 is the ratio of stress to strain at another point of the sample (20 mm upper of the middle of the sample); (3) each sample has 4 strain gauges, 2 on the front and back planes, and the corresponding positions are connected in series (240 Ω) for measurement.