Steinhauer Bridge Underpass

Fort McMurray, Canada

Steinhauer bridge is located along Highway 63 in Fort McMurray crossing the Athabasca River. A parallel bridge was constructed adjacent to the existing bridge, with a new underpass linking the highway to the downtown area. BAUER Foundations Canada Inc. was contracted by Flatiron Corporation to construct a permanent, anchored, secant pile retaining wall.

A total of 205 piles with a diameter of 1,200 mm and 19 m deep, were installed to form a permanent secant pile wall with an overcut of 50 mm between the piles. As per specification all piles had to be embedded 0.5m into competent limestone bedrock. BAUER Foundations Canada Inc. utilized a BG 28 drilling rig and a casing oscillator to twist down temporary casings to the competent bedrock. Both primary and secondary piles were fully reinforced. The primary piles were filled with 25 MPa concrete and the secondary piles with 35 MPa. In order to comply with the specified strict horizontal tolerance and also to stabilize the fill layer on the working surface, a concrete guidewall was constructed prior to commencement of the piling works.

Once the secant piles were completed, BAUER Foundations Canada Inc. installed one pre-production test anchor, and afterwards 285 permanent double corrosion protected tie-back anchors. The anchors were drilled through clay and gravel layers utilizing a KLEMM KR 806-2DB double rotary drill rig equipped with 225 mm diameter casings. Subsequently a special curved anchor plate was placed on the face of the pile wall and stressing took place with test loads up to 800 kN.
The tie-back installation works were completed in harsh winter conditions with temperatures nearing -20 °C. This required specific methods to prevent the grout from freezing and to protect the equipment.