Numerical Study on the Zonal Disintegration of a Deeply Buried High-Temperature Roadway during Cooling

Abstract

Zonal disintegration of surrounding rock is characterized by the intermittent distribution of failure zones, which can be observed in deep underground roadways and tunnels under high-geo-stress confinement. These deep underground roadways can be quite hot and thus require extensive cooling throughout their construction and operation. However, the way in which cooling affects the zonal disintegration of deeply buried high-temperature roadways has rarely been reported. We therefore studied the formation mechanism of zonal disintegration at room temperature using the strength reduction method as part of a self-developed numerical code: RFPA. Subsequently, the effects of cooling and geo-stress on the development of zonal disintegration were disclosed by examining the spatial and temporal distributions of the temperature and stress of the surrounding rock. Numerical results indicated without the thermal stress effect, zonal disintegration is caused by macroscopic shear failure, and cooling transforms the zonal disintegration into a hybrid tensile-shear failure. Although the acoustic emissions quantified revealed that high geo-stress is the primary factor affects roadway instability, the failure area caused by cooling cannot be ignored when it comes to roadway support and stabilization because the time and mechanism that damage the surrounding rock are different from those that caused by geo-stress.