The Flexural Motions of a Floating Ice Sheet Induced by Moving Vehicles

Abstract

AbstractAn extensive series of tests has been conducted on a Roating ice sheet on a deep, fresh-water lake. A variety of vehicles were driven a long an instrumented test track at a wide range of speeds, producing several characteristic patterns of ice and water response that have been recorded and analysed in detail. Tests were repeated at different stages of ice growth to accommodate changes in physical conditions. The use of a vibration transducer and a new type of deflectometer has permilled the study of many primary and secondary effects. As vehicle speed is increased, the ice and water pass through four characteristic modes of response, culminating in a wave effect at the higher speeds. It has been shown that the ice and water waves travel consistently at the speed of the vehicle. This factor has been used to modify a simple ice-wave theory, which then predicts a linear variation of wave frequency with vehicle speed that can be expressed in a universal form for deep -water conditions. The experimental measurements of frequency confirm this universal variation. The observed secondary effects include air-coupled Rexural oscillations, hydrodynamic Auctuations and systematic variations in ice fracture intensity with vehicle speed. This last effect leads to the proposition of a new criterion of vehicle safety.