Direct Tensile Behavior of Limestone and Sandstone with Bedding Planes at Different Strain Rates

• Published in: Rock mechanics and rock engineering Vol. 53; no. 6; pp. 2643 - 2651
• Main Authors: Cen, Duofeng, Huang, Da, Song, Yixiang, Jiang, Qinghui
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.06.2020; Springer Nature B.V
• Subjects: Axial stress; Civil Engineering; Deformation; Earth and Environmental Science; Earth Sciences; Elastic deformation; Fracture surfaces; Geophysics/Geodesy; Intergranular fracture; Limestone; Mechanical properties; Modulus of deformation; Modulus of elasticity; Nonlinear systems; Nonlinearity; Original Paper; Plastic deformation; Roughness; Sandstone; Sedimentary rocks; Stone; Strain; Strain analysis; Strain rate; Stress-strain curves; Tensile deformation; Tensile strain; Tensile strength; Tensile tests; Transgranular fracture; Yields; Bedding plane; Tensile deformation; Tensile strength; Direct tension; Strain rate
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-020-02070-x

To investigate the tensile behavior of rock bedding planes, a series of direct tensile tests were conducted on cylindrical limestone and sandstone specimens with a distinct bedding plane perpendicular to the axial direction. Different tensile strain rates of the bedding plane areas within the magnitude range from 10 −6 to 10 −2  s −1 were considered. The results indicate that the limestone fracture surfaces maintain the original roughness of bedding planes with few grain fractures. However, the sandstone fracture surfaces display many intergranular and transgranular fractures and are rough at the grain scale. The stress–strain curves of limestone specimens can be divided into elastic deformation stage and yield stage (the nonlinearity of yield stage is weaker with the increase of strain rate), while that of sandstone specimens develop in a nonlinear way accompanied by plastic deformation throughout the loading process. The strain rate significantly affects the tensile deformation and strength of the tested specimens (except the average deformation modulus of sandstone specimens). The elastic modulus, average deformation modulus, peak strain and tensile strength increase as strain rate goes up and have a linear relation with the logarithm of strain rate under the tested strain rate range (namely, under a relatively low strain rate range).