Retention of Hillside above the Ollargan-Nervión water main
Project management:
Execution period:
Bilbao Bizkaia Waters Consortium (CABB)
4,275,760 €
SGS (Andrés Pérez)
June 2006 - September 2007


The purpose of the project was primarily to execute a discontinuous retaining wall, made up of isolated elements of retaining wall braced overhead by a pile cap slab.

Each retaining wall element has a T-shaped transverse section and is made up of a core 1 metre thick and 5.0 metres long, and a wing situated at the head of the core (towards the South), in contact with the former, 3 metres long and 1 metre thick.

The purpose of the core is to sufficiently resist slippage of the unstable surface, and to succeed in knitting together the interface or the potential slippage planes so as to achieve a suitable coefficient of secureness.

The purpose of the wing is to reduce the free distance or opening between the different elements, thus contributing to the arch effect in the surrounding land, and transmitting the thrusts received by the core.

While the work done by each element's core is essential due to shear and longitudinal bending, the work done by the wings is so due to shear and transverse bending.

The distance separating the core axes of the different retaining wall elements is 5 metres. Execution included a total of 26 elements, of variable lengths since they all support or are slightly embedded in the rocky substrate (slightly weathered calcareous shale).

The average depth of each retaining wall element is approximately 14 metres, while the actual depth varies from about 9 to 18 metres.

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