Field Tests of Deep Power-installed Screw Anchors in Permafrost

• Published in: Canadian Geotechnical Journal
• Main Authors: Johnston, G. H., Ladanyi, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1974
• Subjects: Civil and Structural Engineering; Geotechnical Engineering and Engineering Geology; Ice; permafrost
• Online Access: http://dx.doi.org/10.1139/t74-036; http://www.nrcresearchpress.com/doi/pdf/10.1139/t74-036

A test program was conducted in northern Manitoba to evaluate the creep behavior and load capacity of 8-, 10-, and 15-in. (20.3-, 25.4-, and 38.1-cm) diameter power-installed screw anchors embedded in permafrost (frozen, stratified silts and clays containing ice at about 31.5 °F (−0.3 °C)). The test results show that the anchors behaved under uplift loads, in a manner that was essentially very similar to that exhibited by deep footings of the same size. No failure planes (slip surfaces) were observed around the plates but a deformed zone above the plates was clearly visible in the varved soil when the anchors were excavated after testing. A method of analysis which allows the test data to be used directly for design, based on secondary creep rates and allowable displacements, is described.