Precast segmental lining for dual-use conduits 08 Feb 2018

CBE of France has designed moulds to produce precast concrete segments to line oval shaped dual-use tunnels. These utility conduits are usually built of concrete panels that are difficult to manipulate and unsuitable for automated production. The CBE segmental alternative allows for standardization of the precast concrete production.

Segment section being lifted from the mould

Segmental lining for dual use tunnels

Ordered initially by the Financial Board for Public Works of Chengdu, in Sichuan Province, China and with the Railway Group No23 construction company, the segment moulds and carousel were designed by the CBE design office in Saint-Avertin, France. While the carousel remains quite standard, aside from a small adaptation on the concreting station, the moulds had to be adjusted to suit the oval shape of two divided dual-use tunnels. One of the tunnels hosts sewage flow and installation of cables, and the second accommodates water supply and electricity cables in its compartments.

The project in Chengdu is believed to be the first of its type lined using rings of precast concrete segments. The lining of the 7.83m wide x 3.8m high tunnels comprises five segments in each 6.27m to 2.7m wide by 0.3m thick bolted and gasketed ring.

Advantages of the alternative included time savings, ease of handling of the precast elements, and improved resilience of the tunnel. The success of the first projects using the system is expected to catch the interest of other cities wanting to simplify the construction process of similar utility conduit projects.

As well as the engineering of steel moulds, precast factories and maintenance equipment to manufacture concrete segments for all sorts of tunnels, CBE has manufacturing production sites in L’Ile Bouchard, France and in Yangling, China. Its group company ACIMEX designs and manufactures vacuum devices for the handling of concrete, steel or PVC pieces. Using vacuum technology or hydraulic clamps, these systems are able to lift and handle loads of up to 30 tonne in full safety.