Implementation of MSE structures as direct bridge abutments have become a significant simplification in the design and construction of bridge abutment systems. This system brings benefits like faster construction, cost savings due to elimination of deep foundations, better compatibility of deformation between the components of bridge abutment systems.
Initially in the 60’s and 70’s, the mechanically stabilized walls were built using steel reinforcement or steel mesh as reinforcement elements. Subsequently, with the development of polymers, geosynthetics were introduced as a substitution to steel elements (in the early 80’s). Over the years these materials have been displacing the steel elements as the main reinforcement system. In this way the concept of Geosynthetic Reinforced Soil (GRS) was born.
This study presents the use of the first GRS bridge abutments as direct support of bridges on a major highway project in Costa Rica. This project includes 4.1 kilometers of a urban highway which has a 1.5 kilometer viaduct with several ascent and descent ramps.
The overpass will be reinforced with 18 kilometers of marginal roads with level sections, which will allow fluid interconnection so that vehicles can pass through the lower part of the viaduct. All these works imply the need to build more than 25 walls of reinforced soil with variable heights of 3 m to 13 m in height, of which 4 have already been completed.
This project has the particularity that several of the structures correspond to walls to directly place the superstructure loads on the reinforced fill (“True Abutments”). The walls have variable heights between 3.4 and 6 m, with maximum reinforcement lengths of 9 m. The length of the span to be covered is 30 m maximum.
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