Calf Robe Bridge Abutment Stabilization: Case Study

ABSTRACT: This technical paper provides a comprehensive account of the abutment stabilization project undertaken by GeoStabilization International (GSI) at the Calf Robe Bridge in Calgary, Alberta. The project involved installation of a discharge conduit through the toe of the bridge abutment to facilitate a downstream discharge from the Bonnybrook Wastewater Treatment Plant (BBWWTP). Before the wastewater infrastructure could be installed, the non-cohesive soils at the abutment needed a bespoke stabilization solution, including the excavation of a 75° slope. Core samples of the underlying bedrock suggested the presence of a possible shear band within the mudstone that interlayered with more competent sandstone. The design-build solution chosen to stabilize the abutment to allow for the installation of conduits is presented in this paper. The solution consisted of the installation of 280 hollow bar soil nails with a 150 mm reinforced shotcrete facing. To mitigate against the potential shear band, the design called for the installation of 118 drilled reinforced concrete shafts. This paper presents the solution and addresses the challenges associated with excavation, installation of soil nails and drilled shafts, load testing methods, and QA/QC testing. Overall, this project is an impressive feat of engineering and an excellent example of GSI's expertise in providing innovative stabilization solutions.