Mechanical behavior of Beishan granite samples with different slenderness ratios at high temperature

Qiang Zhang , Yanjing Li , Ming Min , Binsong Jiang

Abstract

This paper aims at the temperature and slenderness ratio effects on physical and mechanical properties of Beishan granite. A series of uniaxial compression tests with various slenderness ratios and temperatures were carried out, and the acoustic emission signal was also collected. As the temperature increases, the fracture aperture of intercrystalline cracks gradually increases, and obvious transcrystalline cracks occurs when T > 600°C. The failure patterns change from tensile failure mode to ductile failure mode with the increasing temperature. The elastic modulus decreases with the temperature and increases with slenderness ratio, then tends to be a constant value when T = 1000°C. However, the peak strain has the opposite evolution as the elastic modulus under the effects of temperature and slenderness ratio. The uniaxial compression strength (UCS) changes a little for the low-temperature specimens of T < 400°C, but a significant decrease happens when T = 400°C and 800°C due to phase transitions of mineral. The evolution denotes that the critical brittle-ductile transition temperature increases with slenderness ratio, and the critical slenderness ratio corresponding to the characteristic mechanical behavior tends to be smaller with the increasing temperature. Additionally, the AE quantity also increases with temperature in an exponential function.

Key Words

rock; mechanical behavior; acoustic emission; high temperature; slenderness ratio

Address

Qiang Zhang, Yanjing Li and Binsong Jiang — School of Mechanics and Civil Engineering, State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
Ming Min — School of Civil and Hydraulic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

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