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Geogrid ‘Tie-Back’ System Used to Complete Pre-Cast Concrete Bridge Abutments

Geogrid reinforcement of bridge abutments is used to complete pre-cast ‘kit’ bridge systems in Australia. The system comprises piles, cast in-situ footings, pre-cast abutments and wingwalls. Pre-cast concrete beams and deck complete the system. The abutments and wingwalls are “tied-back” with geogrid to form a reinforced soil block which supports the structure against the various modes of · failure. This tie-back system effectively creates a reinforced soil block behind the abutments which does not rely on cantilever action and hence is not subject to such problems. The structural flexibility of this system enables it to accommodate differential settlements when building on soft soils. Up to 20mm to 30mm of lateral movement of the abutment was allowed for in the design, however actual movement was around half of this. Construction