Research on Fracture Toughness of Flattened Brazilian Disc Specimen after High Temperature

Abstract

Fracture toughness is an important parameter to study fracture characteristic of rock under external loads. Based on splitting tensile test on flattened Brazilian disc specimen of rock after high temperature, load–displacement curves of rock sample in the fracture process are obtained and three mechanical parameters of rock including fracture toughness, splitting tensile strength and elastic modulus are calculated according to the experiment. Then, the change rules of fracture toughness, splitting tensile strength and elastic modulus with temperature are discussed, and the relations between splitting tensile strength, elastic modulus and fracture toughness are established. Experimental results show that there exist two inflection points in load–displacement curves. The fracture toughness, splitting tensile strength and elastic modulus reduce gradually with increasing temperature, among which, the mechanical parameters of granite decrease approximately linearly while that of marble decrease approximately as exponential function. There is a close connection between splitting tensile strength, elastic modulus and fracture toughness, nearly a good linear relationship. Since the test method of splitting tensile strength is relatively simple and that of fracture toughness is complex, the fracture toughness can be roughly estimated by splitting tensile strength.

Keywords

• granite
• marble
• high temperature
• flattened brazilian disc
• fracture toughness
• 2010. 62.20.fe