Effects of specimen size and thermal-damage on physical and mechanical behavior of a fine-grained marble

• Published in: Engineering geology Vol. 232; pp. 46 - 55
• Main Authors: Rong, Guan, Peng, Jun, Yao, Mengdi, Jiang, Qinghui, Wong, Louis Ngai Yuen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 08.01.2018
• Subjects: Microscopic observation; Rock strength; Size effect; Thermal damage; Uniaxial compression test; Uniaxial compression test; Rock strength; Microscopic observation; Thermal damage; Size effect
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2017.11.011

Both thermal damage and specimen size have a significant influence on the rock strength and deformation behavior. This study experimentally investigates the combined influences of thermal damage and specimen size on the strength and deformation behavior of a fine-grained marble. Uniaxial compression tests on specimens with different specimen sizes (diameters of 25, 50, 75, and 100mm) and different treatment temperatures (25, 200, 400, and 600°C) are conducted. After thermal treatment, the measured P-wave velocity is found to decrease and the amount of micro-cracks generated inside the specimen shows a drastic increase, indicating an increase in the thermally-induced micro-crack damage. The uniaxial compressive strength (UCS) is found to decrease with the increase in the treatment temperature and decrease as the specimen diameter gradually increases. The Young's modulus also gradually decreases with the increase in the treatment temperature. The peak strain corresponding to the peak strength gradually increases with the increase in the treatment temperature and shows a decreasing trend as the specimen diameter increases. The maximum volumetric strain is also found to show an increasing trend as the applied temperature increases. Rock specimens generally fail in a brittle splitting manner. The integrity of specimens after failure with higher temperature treatment will be lower than those with lower temperature treatment. By using a temperature dependent parameter, a new model which considers the combined effects of specimen diameter and treatment temperature is proposed. •Thermal damage significantly weakens physical and mechanical properties of rocks.•More thermal micro-cracks will be induced as applied temperature increases.•Specimen diameter has a significant influence on performance of rocks.•A new model is proposed to consider both specimen diameter and temperature.