Geotechnical Design:Deep Water Pontoon Mooring Anchors

Anchoring floating structures in deep water can be challenging because of varying water depths, soil types, uses, and environmental loads. Three different anchor types - drilled shaft, gravity, and fluke anchors - were used to meet these challenges for the new SR520 Evergreen Point Floating Bridge and Landings project in Seattle, Washington. The anchors were designed to resist the horizontal and vertical components of the maximum resultant anchor cable load of 570 tons under static and seismic conditions. The anchors are being proven through exhaustive full-scale field load tests. Verification tests are being loaded to a maximum of 570 tons, performance tests to 425 tons, and proof tests on all remaining production anchors to 300 tons. All anchors tested to date, including all performance and verification tests for all three anchor types, have met all (creep and total displacement) testing requirements.