The bearing capacity of ice covers under static loads

Abstract

There is a growing interest in the use of ice covers to support loads for extended periods of time. Current practice for determining safe ice thicknesses for over-ice operations is essentially empirical, being based on experience and limited prototype testing. In this paper, the implications of a design criterion for the static load problem, which limits the maximum vertical deflection to the freeboard, are considered. An expression relating strain and deflection is developed. Field results for a static loading case were analyzed and indicated that the time dependent deflected shape of the ice cover could be represented using elastic theory and a time dependent Young's modulus. By combining the strain–deflection relationship with the deflection limit criterion it is shown that strains are small (i.e. less than 10−3 and in the primary stage of creep) for most cases of practical interest. A method, based on a correlation of observed deflection rates and associated initial elastic stresses from reported cases of static loading of ice covers, is proposed both as a design approach and a framework for analysis of field data.