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Moving loads on sea ice

ABSTRACT A load moving on sea ice, whether the weight of a vehicle or the pressure exerted by a low-flying aircraft, produces a deflection which can in extreme cases cause ice failure. The magnitude and shape of the deflection profile depends on the weight and speed of the vehicle) and also the the ice thickness and properties, with flexuralgraviry waves radiating from the source at speeds above a critical value. This wave pattern was studied in detail on flat, snow-free sea ice in McMurdo Sound, Antarctica. Surface strain was measured directly and microcracking activity monitored to correlate measured strain with possible generation of dangerous cracks. Speeds of up to 28 m sec-1 (60 mph) were achieved with a pickup truck, and up to 80 m sec-1 with a US Navy C131 aircraft. Initial comparison between theory and experimental results is very encouraging.