Laboratory Testing for Adfreeze Bond of Sand on Model Steel Piles

Abstract

This study explored the available adfreeze data published in literature and the techniques used to obtain it. Two methods were selected and modified to complete series of adfreeze bond test. A model pile pull-out method consisting of pulling a pile out a large specimen of soil was the first method used. The second method was modified from an interface shearing apparatus developed by Dr. Fakharian and Dr. Evgin at the University of Ottawa in 1996 and allowed preparing, freezing and testing the specimen in place. The material and soil tested for this study were provided by EXP Services Inc. The model pile, a galvanized HSS 114.3 x 8.6 section, is commonly used to install solar panels. Soil was taken from a future solar farm site in proximity to Cornwall, Ontario. The study had for objective to develop a low cost adfreeze laboratory testing method. Limitations of the technics and apparatus used were observed. While the results of a model pile pull-out test compared to previous data publish by Parameswaran (1978), the interface shear series of test presented more limitations. The interface shearing method has been previously study by Ladanyi and Thériault (1990). Issues with the interface shear method due to the water content of the soil as well as the range of normal stress applied to the specimen both during testing and freezing. The data obtained was inconclusive and the method will be studied in future research program. This studied approach the adfreeze testing with new improvement. The main contribution of this study is the data obtained by measuring and observing adfreeze of ice poor sand with varying water content. The measurements allowed to study the effect that increasing water content has on the interface bond strength. The modifications made to interface shear apparatus are also major new contribution provided by this research. The apparatus was converted in a small freezer chamber using insulation panel and vortex tubes. Which was used to freeze the specimen in the testing chamber and testing adfreeze in place without handling the shear box arrangement.