Effects of High Temperatures and Loading Rates on the Splitting Tensile Strength of Jointed Rock Mass

The splitting tensile tests on the artificial jointed rock mass specimens were carried out using cylindrical samples after being exposed to high temperatures. The effects of the dip angle of joint plane, the radial elastic modulus, the radial peak strain, the damage variable D, the loading rate and the high temperature on the tensile strength of the jointed rock mass were investigated. Test results show that: (1) when the past-exposed high temperature is the same and the dip angle β (the angle between the joint plane and the horizontal plane) of joint plane increases from 0° to 90°, both the tensile strength and the radial elastic modulus first decrease and then increase. However, the damage variable D increases with the dip angle β rising from 0° to 60°, and decreases with the dip angle β elevating from 60° to 90°. (2) When both the dip angle β and the loading rate are the same, as the exposed high temperature increases from room temperature 25 to 400 °C, the tensile strength, the radial elastic modulus decreases and the radial peak strain all gradually decrease, whereas the damage variable D increases gradually. (3) When both the dip angle β and the past-exposed temperature are the same, as the loading rate increases from 0.05 to 5.0 mm/min, the tensile strength and the radial elastic modulus both increase gradually, whereas the damage variable D decreases gradually.