24XT Geogrid Hwy 1 Pile Embankment
Location: Trans Canada Highway 1- Sprott Street Overpass- Burnaby, BC Timeframe: April 2011- June 2011 Scope of Work: Building up a pile embankment for highway overpass extensions with use of Mirafi’s 24XT geogrid Project Partners: Owner:PMH1- PK/F Joint Venture Client: Peter Kiewit & Sons Material supplier: Mirafi/ TenCate
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The soil conditions at the Burnaby section of the Trans-Canada Highway are water saturated and make for a poor foundation to construct roadway overpass extensions. This is due to the geographical location of the road which is situated within the Burnaby drainage basin. The main challenge was to source a reinforcing geosythetic that had sufficient strength and the required soil interaction requirements. As with all design build projects once the design is finalized the construction is fast tracked which required that the selected geosynthetic material be readily available upon short notice.
Layfield in partnership with Mirafi/ TenCate were able to assist the contractor and the geotechnical engineering firm with preliminary design recommendations. The selected material to meet the challenge criteria was the Miragrid® 24XT. It is composed of high molecular weight, high tenacity polyester multifilament yarns which are woven in tension and finished with a PVC coating. It is inert to biological degradation and resistant to naturally encountered chemicals, alkalis, and acids.
The Miragrid® 24XT met the strength requirements with long term design strength (LTDS) of 219.2 kN/m; which is not readily available in polyethylene based geogrids. Its soil interaction properties also met the required coefficients of direct sliding, and pullout.
The client remains impressed with both the Miragrid® 24XT’s performance and Layfield’s ability to service a very demanding project schedule. The material’s large roll dimensions are easy to work with and increased installation productivity. For future phases of the project custom roll lengths will be manufactured to further reduce installation time and significantly reduce product waste producing a significant cost savings for the owner and contractors.