Tunnelmuren

Tunnelmuren is the Swedish term for the tunnel lining, the structural shell that lines the interior of a tunnel. Its primary purpose is to transfer loads from the surrounding ground to the tunnel axis, provide a seal against groundwater, and create a safe, functional space for traffic, utilities, or transit systems. The lining can be monolithic, formed in place, or segmental, composed of pre-cast rings, and is designed to withstand earth pressures while controlling water ingress.

Common configurations include a primary lining and a secondary lining. The primary lining may be cast in place, sprayed concrete (shotcrete), or built from pre-cast segments. The secondary lining, often concrete or reinforced concrete, adds stiffness, improves waterproofing, and enhances fire resistance. Between layers, waterproofing membranes, drainage systems, and insulation may be installed to manage water and temperature.

Construction methods vary by project and geology. TBMs (tunnel boring machines) with a segmental lining are widely used for long tunnel drives, while cut-and-cover or immersed-tube methods are chosen for other scenarios. In soft ground, shotcrete provides initial stabilization before a more permanent lining is installed. Grouting, rock bolts, and other stabilization measures reduce voids and ground convergence around the tunnel.

Design and maintenance considerations focus on ground conditions, load and pressure, hydrostatic forces, temperature, and fire safety. The lining must remain watertight and structurally sound over time. Regular inspections monitor cracks, leaks, and corrosion, with rehabilitation options ranging from resealing and patching to replacement of lining segments or retrofitting insulation and protective measures.