Date:
2020
Contractor:
LOPESAN
Owner:
Cabildo de Gran Canaria
The purpose of the bridge built was to rehabilitate the roadway of the GC-1 Highway on the Island of Gran Canaria, which was partially cut off due to the breakage of a retaining wall, which caused a landslide.
After the collapse, some urgent works were carried out to restore vehicle traffic capacity. A provisional diversion was built, capable of accommodating three traffic lanes and, among other complementary measures, a containment work was carried out on the existing infrastructure by means of a screen of micropiles in order to prevent its subsequent collapse, given the existence of open surface cracks. on the pavement.
The collapse caused a gap in the space where the roadway was previously located, leaving the land cut at the limit marked by the micropile screen, discovered in the outer area and to which a shotcrete coating was subsequently applied.
After the execution of the provisional diversion of the roadway and containment of the area that has not collapsed, the need to adopt a definitive solution was raised to rebuild the original roadway in its original position, with safety guarantees.
The collapse had caused an empty space of the land on which the road previously ran.
General characteristics of the road rehabilitation bridge:
– The road has been supported by a structure that jumps over the area affected by the collapse.
– The structure covers the space by means of a bridge deck with a span of 40 m and a width of 15 m, founded by means of micropiles embedded in the rocky massif that underlies the layer of loose soil.
– Part of the new deck occupies the empty space created by the collapse and the entire layout of the GC-1 roadway has been restored in its original position.
One of the most relevant data that has conditioned the project of the developed solution has been the consideration of the space available for the construction, which was formed by a narrow strip between the right limit of the road detour and the edge of the land cut by the landslide.
Specifically, to build the 15-meter-wide deck, only one passageway was available with a useful width slightly greater than 7 meters. Due to this difficulty, the choice of typology was strongly conditioned by feasibility requirements, as well as by those of the corresponding construction procedure and the use of adequate auxiliary means to operate in such a small space.
The construction has been carried out in independent phases, each one of them, to create a fraction of the structure with the capacity to support the own weight of the following one, in assembly state.
The deck structure is formed by a resistant core built on the existing passageway, whose width is slightly more than 7 m. The core, with a span of 40 m, a width of 6.20 m and a total thickness of 2 m, has been concreted on the ground itself, previously excavated to the necessary depth, which has acted as a supporting formwork for the formwork of the lower part.
Once the stressing process of the active reinforcement of the core has been completed, the load due to its own weight has been transferred to the support area.
Once the core was built, it was used to create a 5.85 m cantilever, made up of lightweight prefabricated elements assembled with auxiliary elements that run above the core itself.
After the assembly of the large cantilevered area, a resistant deck 12 m wide has been created for the passage of vehicles. Once this point has been reached, traffic has been restored on the constituted deck and with the definitive layout, albeit with a road with 3 strict lanes, pending the completion of the construction of a small overhang on the inner side, which occupies part of the detour that had been rendered useless.
– Finally, once the 15 m width of the deck has been completed, the roadway has been definitively established in its original position, provided with 3 circulation lanes, plus a hard shoulder on the right side and a berm on the inside, on the left side:
The limitations of useful space for the construction have motivated the carrying out of the process, through phased assembly of the fundamental elements, of a structure whose morphology has been conditioned by the demands of the construction process to follow.
The cantilevered area of the deck is formed by the association of several prefabricated elements (brackets and precast slabs), which support a concrete slab to be built in situ.
With this procedure, a cantilever close to 6 meters has been built, which is embedded in the core and anchored at the top with the addition of a transverse prestressing.
