Modelling Fracture Propagation in Shallow-Buried Road Tunnels Using an Empirical Approach

Abstract Fracture propagation in road tunnels significantly impacts tunnel stability and safety, requiring accurate prediction models for effective risk management. This study developed an empirical model to forecast fracture propagation in shallow-buried tunnels, based on microfracture characterisation. Field observations, thin section analysis, aeromagnetic surveys, microfracture analysis, and data analytics were used to examine fracture patterns and their impact on tunnel design. Three primary types of fractures (i.e., trans-angular, inter-angular, and grain boundary fractures) were identified. These fractures showed an uneven distribution along the tunnel profile. The empirical model highlights variations in fracture density, decreasing from the tunnel entrance toward the middle section. An empirical chart illustrating fracture distribution was created to assess fracture-related hazards and guide engineering decisions in tunnelling projects. The findings offer valuable information on fracture propagation mechanisms in road tunnels and contribute to improving the safety and stability of tunnel infrastructure.