Cut and covers tunnels
The cut-and-cover method is ideal where a motorway or main line or underground railway has to be sunk just below ground level to pass through built-up areas.
It consists of a pair of parallel sidewalls (usually diaphragm walls) spanned by a cover slab to restore street level traffic.
The tunnel is excavated once the cover is in place. The cut-and-cover method is also used for the final sections of motorway and railway tunnels where they emerge at ground level. Bachy has many successful projects of this type to its record.
Metros stations, launching shafts
The 1960's saw the beginning of the rapid growth of cities, accompanied by a demand for underground high-speed transport systems, Soletanche Bachy has been involved in building most of the challenging underground stations, performing the soil consolidation grouting, cut-and-cover tunnels with cast-in-place diaphragm sidewalls and major underground openings. The most recent jobs of this type were located in Hong Kong, Singapore, USA, plus many smaller examples.
Soil Improvments
For transportation engineers, it is often difficult to avoid encounters with highly compressible soils. For example, in the case of crossing wetlands it is necessary to consolidate the in-situ soil in order to avoid slope failure of the future road embankments during construction.
Pre-consolidation of the most compressible areas is necessary to prevent long term creep settlement. The consolidated soil foundation will increase and preserve the service life of the road pavement, thus reducing life-cycle costs for the roadways and structures. Access embankments which lead to bridge structures induce critical loads to the subsurface soil levels. The designs for these foundations routinely require intensive treatment to improve the soils.
