Online Published on 27 June, 2025.
The intersection of tunnels, particularly where multiple tunnels converge (such as a Main Access Tunnel (MAT) and an Adit), presents a complex three-dimensional engineering challenge due to the intricate behaviour of rock masses and the stresses generated during construction. Traditionally, a support system stronger than that used in regular tunnel sections has been employed to mitigate the adverse effects of these complex stress conditions. This paper highlights several key issues encountered during tunnelling in such challenging geological conditions. The case study discussed focuses on the design of junctions connecting the MAT and Adit, utilizing sprayed concrete lining and rock bolts, and is analysed through three-dimensional numerical modelling using MIDAS FEA NX.
