PERFORMANCE OF GEOSYNTHETIC-REINFORCED WALLS SUPPORTING THE FOUNDERS/MEADOWS BRIDGE AND APPROACHING ROADWAY STRUCTURES. REPORT 1: DESIGN, MATERIALS, CONSTRUCTION, INSTRUMENTATION AND PRELIMINARY RESULTS

In July of 1999, the Colorado Department of Transportation (CDOT) successfully completed the construction of the new Founders/Meadows Bridge near Denver. In this project, both the two-span bridge and the approaching roadway structures are supported by a system of geosynthetic-reinforced segmental retaining walls. The reinforced soil system not only provides bridge support, but it was also designed to alleviate the common bridge approach bump problem. Placement of shallow foundations supporting the high bridge superstructure loads on the top of mechanically stabilized earth (MSE) walls leads to reinforcement tensions and soil stresses mobilized in a different manner than in the case of MSE walls supporting small surcharge loads. This structure was considered experimental and comprehensive material testing and instrumentation programs were conducted. These programs would allow assessment of the overall structure performance and evaluation of CDOT and AASHTO design assumptions and procedures for reinforced soil structures supporting both bridge foundations and approaching roadway structures. Three sections were instrumented to provide information on external movements, internal soil stresses, temperatures, moisture content, and geogrid strains during various construction stages and after the structure opening to traffic. This report initially presents an overview of the reinforced soil wall system design, materials, construction stages, and the instrumentation program. Results of large-size triaxial and direct shear tests on the gravelly backfill soil material and preliminary instrumentation results are presented and discussed. The instrumentation results suggest that the overall performance of this structure, before its opening to traffic, has been satisfactory. CDOT design guidelines of assuming zero cohesion for the backfill strength and testing specimens without the gravel portion of the soil lead to significant underestimation of the actual shear strength of the backfill. The design and construction of geosynthetic-reinforced walls supporting bridge and approaching roadway structures should be considered in the future for field conditions similar to those encountered in the Founders/Meadows structure. CDOT design procedure should be enhanced and made more flexible to employ the proper shear strength parameters of the backfill.

  • Corporate Authors:

    Colorado Department of Transportation

    4201 E Arkansas Avenue
    Denver, CO  United States  80222

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Abu-Hejleh, N
    • Outcalt, W
    • Wang, Ting
    • Zornberg, J G
  • Publication Date: 2000-6

Language

  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 105 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00800166
  • Record Type: Publication
  • Report/Paper Numbers: CDOT-DTD-R-2000-5
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Oct 11 2000 12:00AM