Experimental investigation of the effect of thermal treatment on shear characteristics of healed rock joints

Understanding the temperature-dependent shear behavior of rock joints is significant for the design, construction and maintenance of deep rock engineering. However, the shear characteristics of healed rock joints under high temperatures are still poorly understood. In this paper, to capture the thermal effect on the shear behavior of healed rock joints, a series of direct shear tests are performed with the aid of X-ray diffraction and scanning electron microscope techniques. The testing results demonstrate that the shear resistance of the healed joints is slightly lower than that of the intact rock, but much greater than that of clean joints. Compared with intact rocks, the ductile failure characteristics of the healed joints after high temperature thermal treatment are more sig-nificant. The peak shear strength, shear stiffness and dilation angle of healed joints are greatly influenced by thermal treatment temperature, while the ultimate shear strength is almost independent on with temperatures. The influence of thermal treatment on shear resistance is attributed to the physical and chemical changes. The thermal decomposition of the filling minerals at around 400 ?& nbsp;is believed to be the main cause of the change in thermal-induced shear behavior of the healed joints. The findings of this work are useful to understand the mechanical behavior of jointed rock mass under high temperatures.

Automated summary

Understanding the temperature-dependent shear behavior of rock joints is crucial for deep rock engineering. The shear characteristics of healed rock joints under high temperatures show slightly lower resistance than intact rock but significantly more than clean joints. Thermal treatment greatly influences the peak shear strength, shear stiffness, and dilation angle of healed joints, while the ultimate shear strength remains almost independent of temperature.