摘要: |
In 1996, research geologist Michael Adams successfully smashed the world's record for load capacity and applied pressure on a geosynthetic reinforced soil (GRS) structure with the 5.5-m (18-ft) tall bridge pier that he designed on the grounds of the Turner-Fairbank Highway Research Center (TFHRC) in McLean, Virginia. During the winter of 2000 in Las Vegas, Nevada, Adams' experiment, dubbed the Vegas Mini-Pier, was loaded to an equivalent stress of 1,000 kilopascals (145 lb/sq in). The vertical and lateral strain to the pier at that pressure was approximately 3%. Adams has designed other GRS structures with vertical and lateral strain as low as 0.5%. Shortly after the construction of the bridge pier at TFHRC, a Colorado Department of Transportation maintenance crew built a rectangular prototype abutment, a rectangular pier, and an oval pier along Interstate 70 using GRS technology. Construction of the piers and abutment was rapid and simple. The structures successfully supported a load equivalent to 230 kilopascals (33 lb/sq in), which was more than expected. Early in 1999, two full-scale approach embankments and abutments for a single-span bridge were built at TFHRC using GRS technology. The abutments were designed according to Adams' strong belief that the spacing of reinforcement layers is more important than the strength of the reinforcement itself. They feature weaker, but more closely spaced, reinforcement layers between the compacted fill layers. During testing in October 1999, a prestressed concrete box girder was placed on the geosynthetic bridge abutments. The girder was loaded until it cracked significantly, but the GRS bridge abutments performed successfully. Even though the bridge beam was supported directly by the GRS abutments, no settlement of the abutments was recorded. |