Abu-Hejleh, Zornberg, Elias, and Watcharamonthein 1 DESIGN ASSESSMENT OF THE FOUNDERS/MEADOWS GRS ABUTMENT STRUCTURE By:

Front abutment Geosynthetic-reinforced soil (GRS) walls were constructed to support the shallow footings of a two-span bridge and the embankment approach roadway structures. A key element in the design was the need to support the concentrated loads from the bridge footing and to alleviate the "bump at the bridge" problem. Past publications summarized the design, materials, construction, instrumentation, and the overall movement performance of this structure. The focus of this paper is to evaluate briefly the loading response of the front abutment GRS walls under service loads based on measured lateral earth pressures against the wall facing, vertical earth pressures, and geogrid reinforcement strains inside the wall. Data was collected during construction of the GRS wall, during five stages of bridge superstructure construction, and during 33 months after opening the bridge to traffic. This paper also presents an assessment of the design of the front abutment GRS walls. The overall loading response of the front abutment GRS wall was excellent. The measured loads, especially behind the wall facing, were below the design values, and the overall stability of the structure as measured by load eccentricity was much greater than projected in the design. The use of GRS walls to support both the bridge and approaching roadway structure has been approved by Colorado DOT (CDOT) as a viable foundation support system in future bridge abutment projects. Finally, preliminary recommendations for design and construction of future GRS abutments are provided.