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

Table 5

Results of splitting test of marbles.

Sample no.	Diameter, d (mm)	Height, h (mm)	Failure load, P (kN)	Tensile strength, σt (MPa)	Tensile modulus, Et (GPa)	Modulus 2, E2 (GPa)	Remarks
18	49.18	26.23	17.45	8.61	19.39	26.82
19	49.20	25.35	9.407	4.80	18.82	21.42
20	48.96	25.10	15.96	8.27	17.37	17.67
21	49.12	25.63	11.72	5.93	13.88	11.11
22	49.10	25.35	13.71	7.01	22.53	−34.38
23	49.00	25.26	19.62	10.09	16.15	−41.97

Description: (1) elastic modulus E_t is the ratio of tensile stress to tensile strain in the x direction at the point at the center of the circle, which is the tensile elastic modulus. (2) Elastic modulus E₂ is the ratio of stress to strain at another point of the sample (or the y direction of the point at the center of the circle), and the negative value is expressed as the compressive modulus. (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.