Field Tests of Grouted Rod Anchors in Permafrost

The use of guyed towers for power transmission and communication systems in northern Canada has received increased attention in recent years. In many cases perennially frozen ground (permafrost) poses special problems. The resistance of frozen soil to uplift forces must be evaluated for the design of anchors of guyed structures built on permafrost. There is little experience or information available, however, concerning the behavior of frozen soil in response to uplift forces or the capacity of various types of anchors. A field study of anchors in permafrost was therefore undertaken by the Division of Building Research of the National Research counci l of Canada to evaluate, in particular, the displacements associated with long-term creep of frozen soil under load. initial appraisal of various kinds of anchors suggested that grouted rod anchors were a type that should be investigated. Early in 1967 a total of 18 such anchors (nine at each site) were installed in permafrost at Thompson and Gillam, Manitoba. This paper describes the installation and testing procedures and the results of the test programs conducted on the anchors at both sites. In the analysis of the results the creep behavior of grouted anchors is related to U basic creep parameters of frozen soil, taking into account the effects of temperature and normal pressure. The theory employed allows field creep data to be used for estimating the long-term adfreeze strength of frozen soil, information that is required in the design