Creep of model piles in frozen soil

Abstract

Preliminary results of laboratory studies on the behaviour of model piles of wood, concrete, and steel, having different surface finishes, embedded in artificially frozen sand and subject to constant loads, are reported in this paper. The displacement rate [Formula: see text], was found to vary with the applied stress [Formula: see text]f, according to a steady state creep equation of the type [Formula: see text], as found for other viscoelastic materials such as metals at high temperature. The value of the exponent n varied between 6.7 and 9.1 for various types of piles.The results agreed favourably with field data obtained from pile pull-out tests carried out at Gillam and Thompson, Manitoba. The value of n from Gillam and Thompson tests, 8.05 and 7.5, respectively, were within the range of the present experimental values. Comparison with pile pull-out tests carried out in ice, and theoretical predictions for ice showed that the value of the exponent n was much larger for frozen soil than for ice. The bearing capacity at a particular displacement rate was also found to be almost an order of magnitude larger in frozen soil than in ice.