INNOVATIVE DESIGN-BUILD GROUND IMPROVEMENT SOLUTION FOR SUPPORT OF CENTRAL

The Central Corridor Grade Separation project involves elevating high-use at-grade railroad tracks to enhance traffic flow through the active downtown corridor of Wichita, Kansas. Retaining walls ranging in height up to 25 feet above grade are required to meet existing railroad right-of-way restrictions. The Central Corridor site is underlain by sand and clay fill overlying variable thicknesses of compressible silt and clay. Without soil reinforcement, the construction of the walls over the fill and compressible soils would result in excessive settlements and the high bearing stresses imposed by the walls and rail loads exceeded the soil bearing capacity. Several options were evaluated to support the heavy wall loads and reduce the serviceability risks by limiting settlements. Considerations for potential solutions required that all construction remain within the existing confined railroad right-of-way, and that the construction impact on adjacent structures was minimal. After careful consideration by the design team, the design-build Geopier ® Rammed Aggregate Pier ™ (RAP) system was selected to support the retaining wall. This paper describes the design and construction of the selected alternative. This paper is of particular significance because it represents the first published case history that presents field performance result