When using Gold's formula, a purely elastic response is assumed, which is, by definition, instantaneous and independent of loading time. Maximum loading time įreeboard on an ice road at different time intervals.
#Ice driver terminology professional
higher A values can be used, but under the close supervision of a professional engineer. For industrial roads, the design may be less conservative so as to handle their functional requirements, i.e. Moreover, for a public road, which is relatively uncontrolled, such an approach introduces a high safety factor against breakthroughs and is therefore desirable. This level of conservatism is justified because, unlike human-made materials such as steel or concrete, natural ice covers inherently contain a large amount of structural flaws (fractures, water and air pockets). Although recommended values for A range from 3.5 to 10 kg/cm 2 (~50-150 lbs/in 2), lower bound values are generally those that are used for safety purposes. Hence, with this idealized formulation, A is representative of the ice cover tensile strength.
The parameter C is based on the theory of thick plates. Where σ max is the maximum tensile strength at the bottom of an infinite ice plate resting on an elastic foundation. It may be linked with an idealized elastic response of the ice cover: σ m a x = C P / h 2 Where P is the load, h is the thickness and A is a constant with a unit of pressure.
This formula, which was initially proposed in 1971, is often referred to as Gold's formula: Three loading regimes have to be considered: a) maximum weight for standard usage or for parking during a short duration b) a load that remains stationary during an extensive time period and c) dynamic loading of the ice cover, from a traveling vehicle.įor standard traffic activities, guidelines typically use a simple empirical formula to determine the maximum vehicle weight that should be allowed on an ice road. In order to meet the ice bearing criteria, the top surface should not sink below the water line and the applied flexural stress should not exceed the ice's flexural strength. Generally speaking, a vertically loaded ice cover will react in two ways: 1) it will sink, and 2) it will bend in flexure. The ability of an ice road to safely support the weight of a vehicle (or any other loads applied onto it), referred to as bearing capacity, is the primary concern when designing, building and using that structure. Not to scale - for illustrative purposes only. The pressures of the water, related with ice buoyancy, upon short-term vertical loading an ice cover (adapted from ).
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