structure-medium interaction

Structure-medium interaction in tunneling refers to how the support system and the surrounding ground share the load within a tunnel. Tunnels are categorized by the material they pass through: soft ground, hard rock, soft rock, or subaqueous. Geologic investigation is crucial to understand ground and water conditions, as unexpected geological features can significantly increase costs and construction time.1

The strength of the rock mass, influenced by joints, faults, and other defects, is more critical in tunneling than the strength of intact rock. The existing stress in the ground (geostress) also plays a role. Support systems must be installed promptly to maintain the ground arch effect, which helps carry the load. The choice of excavation method, such as full-face or top heading and bench, depends on the ground's stability and the tunnel's size. Historically, timber and masonry were used for support, but steel is now common, often encased in concrete for permanent lining.23