Mechanical behavior and failure characteristics of double-layer composite rock-like specimens with two coplanar joints under uniaxial loading
(1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. School of Civil Engineering, Hefei University of Technology, Hefei 230009, China;
3. School of Resource, Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
4. Hunan Provincial Transportation Planning Survey and Design Institute Co., Ltd., Changsha 410219, China)
2. School of Civil Engineering, Hefei University of Technology, Hefei 230009, China;
3. School of Resource, Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
4. Hunan Provincial Transportation Planning Survey and Design Institute Co., Ltd., Changsha 410219, China)
Abstract: To study the combined action of joints and bedding plane on crack evolution of flawed layered rock masses, uniaxial compression tests and digital image correlation (DIC) tests were carried out on double-layer composite rock-like specimens with multi-inclination two coplanar joints under different bedding angles. Based on the experimental results, the existence of bedding plane and joints performs a significant effect on characteristics of stress-strain curves and strength parameters. The failure modes are divided into four different types. The existence of bedding plane inhibits the coalescence of cracks in rock bridge area, and the variation of bedding angle affects the crack propagation path and failure mode transition greatly. For specimens with bedding angle of 30° and 45°, the larger the joint angle, the less the influence of bedding plane on failure characteristics. Besides, a new tensile crack type which initiates from the bedding plane and is easier to propagate in the upper layer was observed.
Key words: two coplanar joints; rock-like specimens; crack evolution; uniaxial loading; digital image correlation (DIC) method