Journal of Cold Regions Engineering

An extreme‐value analysis is carried out for ice properties in the Great Belt in Denmark. The Great Belt is an 18‐km‐wide body of water that connects the Baltic Sea with Kattegat and the North Sea. It divides the country of Denmark into halves of nearly equal population. The design of a bridge and tunnel system across the Great Belt called for knowledge of extreme ice properties, because dynamic ice loading governs part of the design. Because of the extremely low exceedance probability of $2\times {10}^{-5}$ per year accepted for ice loading, and because of the very limited amount of data available concerning ice at the location of interest, the analysis had to depend on air‐temperature records. Statistical correlation between strength and thickness of the ice was handled effectively by splitting their product in temperature dependent and independent parts and joining distributions for these by simple integration. The effect of a snow cover on the ice was also analyzed.

Structural design of offshore structures in subfreezing temperatures is an engineering challenge. Design loads vary arbitrarily and are difficult to evaluate. One of the design loads is the live load imposed by drifting ice features in the ocean. These ice features vary from small chunks of ice weighing a few hundred pounds to icebergs, which could weigh hundreds of tons. Their drifting speeds depend on the wind speeds and the ocean currents. Usually the structural columns have ice sheets adfrozen around their periphery. Floating ice features come in contact with these adfrozen ice sheets before ever touching the column surface. This makes it difficult to assess the design loads imparted by the floating ice feature to the structure. This article presents a method for estimating these loads and predicting the behavior of the adfrozen ice plate and the invading ice feature.

Particle size has opposing effects on the effectiveness of freeze/thaw sludge conditioning. Small particles migrate easily and coagulate into larger particles during freezing, but small particles also cause poor sludge dewaterability. Since agitation can change particles size, the effects of agitation on sludge de‐watering before and after freeze/thaw conditioning is of practical significance. The capillary suction time (CST) device is used to measure the dewaterability of several water and wastewater treatment sludges before and after freeze/thaw. The results show that preagitation may have a detrimental effect on the dewaterability of some sludges after freeze/thaw conditioning. For other sludges such as raw primary sludges that have large initial particle size distributions, agitation prior to freeze/thaw will not be detrimental to subsequent dewatering. Postagitation clearly has a substantial deleterious effect on dewaterability, leading to the conclusion that if freeze/thaw is used for conditioning, the thawed sludge should undergo minimum agitation before dewatering.