Consorcio urbanístico, Valdelacasa
FCC CONSTRUCCIONES S.A
In the residential development of Valdelacasa in Alcobendas (Madrid), it was proposed to construct a bridge over a nearby river. The approach embankment leading to one of the bridge abutments was located on soft soils, consisting of a 3 m layer of clay over laid with sand. The 5 m high embankment was 32 m wide with side slopes of 3H/2V.
After discussing various solutions, a decision was taken to install a woven geotextile with a strength of 150 kN/m in its longitudinal direction. In that way, the geotextile strength required to prevent failure of the embankment and extrusion of the soft soil was calculated. Apart from meeting the reinforcement requirements, the geotextile provides separation of the soft soil from the embankment fill material. The installation, carried out in August 2007, consisted of laying the rolls of geosynthetic perpendicularly to the embankment axis. Transverse overlapping between the rolls was 250 mm.
Before beginning construction of the embankment, special care had to be taken to ensure that the rolls had been properly installed so as to avoid folds and wrinkles.
This solution offered the following advantages: it increased the embankments safety factor while eliminating staged construction and dispensing with excavation of the soft soils, in view of the fact that the geosynthetic was placed above these, thus reducing transportation of the soils off-site and, accordingly, reducing the environmental impact of the works.