Transmission Line Foundation Design Using Inclined Earth Anchors-Video

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Video Summary

Darren Ratliff of Ameren Transmission and geotechnical engineer Andy Canopy present inclined earth anchors as a way to supplement drilled-shaft foundations for transmission monopoles in weak soils. Heavy-angle structures face substantial lateral loads from wind and ice, while limited rights-of-way may prevent using more stable tower designs. Where soft clay overlies stronger soil or bedrock, inclined anchors can connect the foundation to the stronger layer, reducing deflection and the size of the drilled shaft.<br /><br />The anchors attach to corbels near the foundation’s ground-line area and are installed and grouted after the pier is constructed. This approach allows drilling and anchor crews to use their standard methods and can help keep projects on schedule. In one comparison, the tieback design reduced concrete use by nearly half. The presenters emphasize that anchors are an additional design option for particularly challenging sites, not necessarily a cheaper solution, and that structural and geotechnical engineers must collaborate closely.

Keywords

inclined earth anchors

drilled-shaft foundations

transmission monopoles

geotechnical engineering

weak soils