Sewer 'Oued Ouchaiah'

Structural design for a sewer with segmental lining

For the construction of a sewer in Algiers, district Bourouba, Algeria, ZPP, working alongside with PSP Consulting Engineers, was awarded with the detailed design of the segmental tunnel lining.

The approximately 2.700 m long sewer will be constructed using mechanised techniques (earth pressure balance shield) and lined with prefabricated concrete segments. The external diameter of the tunnel, which is configured as an open channel sewage, amounts to 4,60 m. The thickness of the reinforced concrete segments is 0,3 m. The soil overburden of the tunnel roof varies between 7 and 34 m. The assumptions concerning the loads and the bedding of the tunnel lining in the different soil layers were determined in consultation with the geologic expert of the performing company.

The structural verification of the tunnel tube was based on the finite element method by means of an embedded framework model with coupled joint rings. The detailed proof was conducted according to Eurocode, as well as based on the recommendations of ”Deutscher Ausschuss für Unterirdisches Bauen” (DAUB).

The guideline concerning a high internal pressure (accidental load case for the open channel sewage) requires a permanent screwing of the segments in certain areas.