Experimental Study on the Evolution Law of Mechanical Properties of High Temperature Granite under Different Cooling Modes

Abstract

Purposes The mechanical properties of granite in the same high temperature state under different cooling modes (thermal shock cooling in water at 20 ℃ and natural cooling in air at 20 ℃) are different. Methods By using the laboratory self-developed thermal shock fracture experimental platform, uniaxial compression, Brazilian splitting, and variable-angle shearing (45°, 55°, 65°) were carried out on granite in different temperature states (25-600 ℃) under two cooling modes. To test its uniaxial compressive strength, stress-strain curve, peak strain, tensile strength, cohesion c, internal friction angle φ and other macro-mechanical parameters. Besides, the evolution of the mechanical properties of high-temperature granite under different cooling modes was studied. Findings The research results show that: 1) the cooling mode has a great influence on the uniaxial compressive strength, tensile strength, and cohesion c, but has little effect on the internal friction angle; 2) The mechanical strength of granite at the same high temperature deteriorates more seriously with thermal shock cooling in water at 20 ℃, and 300 ℃ is the threshold temperature for the difference between the two cooling modes; 3) From 25 ℃ to 600 ℃, compared with natural cooling, thermal shock cooling caused compressive strength, tensile strength, and shear strength (cohesive force) deteriorations of granite which are 51.7%, 33%, and 27.6%, respectively, showing that the cooling mode affects the mechanical strength of granite in descending order: tensile strength, shear strength, and compressive strength. Conclusions The research results can provide test reference for related projects.

Keywords

• high temperature granite
• cooling mode
• thermal shock
• mechanical properties
• evolution law