Influence of temperature on the brittle failure of granite in deep tunnels determined from triaxial unloading tests

Abstract

High ground temperatures lead to the risk of rockburst in hard rock tunnels located in high-stress environments. However, existing rockburst studies have not considered the influence of temperature. Therefore, the laboratory experiments were conducted to measure the brittleness of granite samples under different temperature scenarios, and the tendency of rockbursts were evaluated at different temperatures in this paper. The brittle failure mechanism of granite was explored by using uniaxial and triaxial rock tests under the influence of thermo-mechanical coupling. The results indicated that the post-peak deformation of the rock samples changes from ductile to brittle with an increase in temperature to 100 °C. The frequency of shear failure occurred in this test increases with increasing temperature, and the brittle failure of the surrounding rock is enhanced with an increase in temperature. The results indicated that rockbursts occurring in deep granite tunnels at high ground temperatures will be more intense than those occurring at room temperature. The results of this study can be applied to predict the intensity of rockbursts before the tunnels are excavated.

Keywords:

• Deep tunnel
• rockburst
• high ground temperature
• thermo-mechanical coupling
• temperature effect