GEOTEXTILE EARTH-REINFORCED RETAINING WALL TESTS: GLENWOOD CANYON, COLORADO

The Colorado Division of Highways elected to use flexible reinforced-soil retaining structures to meet architectural and environmental constraints in the design of I-70 at sites underlain by compressible soils in Glenwood Canyon. Four wall systems were constructed: Reinforced Earth, Retained Earth, Wire Wall, and geotextile reinforced walls. The geotextile reinforced-soil retaining wall tests are described, and design, construction, and instrumentation details are provided. The test wall is 300 ft long and approximately 15 ft high. The wall incorporates four nonwoven geotextiles (each in two weights) in 10 test segments. Instrumentation is provided to monitor settlements and surface and internal deformation of the reinforced soil. The test wall has a gunnite facing. The wall was designed by conventional methods; however, some segments were assigned lower-than-usual factors of safety to provide a more critical test. Since construction, the wall has settled from 6 to more than 18 in. due to foundation consolidation. Test wall performance, however, has been satisfactory, and none of the segments has exhibited distress. Wall design and performance relative to laboratory geotextile strength and creep test results are analyzed, and it is concluded that safe, economical geotextile walls can be designed by existing methods if certain factors, as discussed in the paper, are appropriately considered. Recommendations are also made. It is concluded that construction methods are appropriate for contractor-constructed projects. Cost data are also presented. (Author)