Cut and cover tunnel design involves the consideration of many parameters. Cut-and-cover is a simple method of construction for shallow tunnels where a section is first is excavated and then covered over with an overhead support system strong enough to carry the load of what is to be built above the tunnel. The two basic forms of cut-and-cover tunnelling are:
- Bottom-up method: The main site is excavated, with ground support as necessary, and the tunnel is constructed within. The tunnel may be of in situ concrete, precast concrete, precast arches,or corrugated steel arches. The trench is then carefully back-filled above the tunnel roof and the surface is restored.
- Top-down method: Here side support walls and cap beams are constructed from ground level typically with slurry walls, or secant piling. Then a shallow excavation allows making the tunnel roof of precast beams or in situ concrete. The surface is then restored except for access openings. This allows early reinstatement of roadways, services and other surface features. Excavation then takes place under the permanent tunnel roof, and the base slab is constructed.
DeepEX Software is the only software in the world that offers the following capabilities for cut and cover tunnel design:
|- Permanent liner walls with tension gap effects||- Staged construction|
|- Uplift capabilties and water plug considerations||- Thermal effects on slabs|
|- Application of Eurocode 7 with cut and cover tunnels||- Variable surcharge loads on each stage|
Cut and cover tunnel caption from DeepEX software.