Performance of a prestrained geosynthetic reinforced soil bridge pier

A full-scale instrumented bridge pier was constructed and load tested at the Turner Fairbank Highway Research Center (TFHRC) in McLean, Virginia. The pier was 5.4m high and, at it’s base, was 3.6m × 4.8m. The pier successfully sustained a maximum load of 9800kN (2200kips) which is equivalent to a pressure of 900kPa (9.4tsf). The purpose of the experiment was to demonstrate the performance and ability to construct a reinforced soil (RS) bridge pier with segmental blocks. A default/generic method of constructing reinforced soil structures for bridge support was used. This method utilizes closely spaced high-strength geosynthetic reinforcement and quality compacted road base. Construction techniques for this style of segmental wall are also explained. The pier was instrumented to monitor load, lateral deformation and vertical settlement. Several layers of the reinforcement were instrumented with strain gauges to monitor creep and strain in the fabric. A method of prestraining the reinforced soil mass was also tested. Changes in the properties of the reinforced soil due to prestraining were evaluated. The pier was hydraulically loaded to squeeze the reinforced soil vertically. Results of the load test indicate that this type of reinforced soil construction creates a suitable material for simple bridge support. It also demonstrates that it should be routinely considered as an alternate method to stack and retain soil on highway earthwork projects. Connection strength of the facing blocks with fabric tails was very good. The technique provides a sound facing and can be used on any simple wall. Although there are many benefits from this new, modern approach to bridge pier design, it is not applicable to or recommended for every bridge building assignment. Throughout this report major aspects of the pier’s design, construction and load tests results are presented.