ICE FORCES ON AN ISOLATED CIRCULAR PILE

The purpose of this paper is to present a mathematical model for calculating the forces that a moving ice cover will exert against an isolated circular pile. One of the requirements of the model is a knowledge of the relationship between the strain rate in the ice and the rate at which the cover is moving relative to the pile. Two approaches are used to establish this relationship; the first empirical and the second analytical. For the empirical approach, the stress-strain curve observed in the laboratory for constant strain rate tests is made to correspond to the load-penetration curve for a pile test. Both of these curves have a maximum or yield stress for the first cycle of load in the ductile range of behaviour. The assumption made is that the strain immediately adjacent to the central part of the front of the pile at maximum load is equal to the strain associated with the maximum stress for the constant rate of strain tests. This approach is limited at this time because little information is available on the dependence of the load on penetration and rate of penetration of a pile. Noble and Hussain used a stress function for the plane strain case to develop an exact elastic solution for inclusion problems. The results of this investigation were used to develop a relationship between penetration and strain for the pile problem for the elastic condition. This relationship provided the basis for an assumed dependence of strain on penetration when the ice is no longer behaving elastically. Using this relationship it is possible to determine the load on the pile from information on the strength and deformation properties of ice measured in the laboratory. The calculation of the thrust exerted on a pile assumes that the structure of the ice adjacent to the pile deteriorates by the formation of internal cracks. At a critical stress that depends upon the strain rate and temperature, the deterioration is sufficient to allow a zone of failure to develop. In uniaxial compressive tests this coincides with the occurrence of yield. The strain rate in the ice immediately adjacent to the pile is established from the assumed dependence of the strain on the penetration and the rate of penetration. Loads are calculated by assuming the dependence of maximum load on strain rate to be that measured for uniaxial compression. It is appreciated, however, that the failure zone in the pile problem propagates at a different angle relative to the grains of the ice than for simple compression, but no information is yet available on how this will affect the yield stress. Attention is given to the effect of temperature. The calculation is considered valid for the case where the ice is initially in uniform and intimate contact with the pile.

• Supplemental Notes:
  • Abstract of paper delivered at the First International Conference on "Port and Ocean Engineering under Arctic Conditions" held at Trondheim, Norway, August 23-30, 1971
• Corporate Authors:

  POAC Conference

  ,    
• Authors:
  • Frederking, R
  • Gold, L W
• Publication Date: 1971

Subject/Index Terms

• TRT Terms: Cold weather construction; Force; Ice; Loads; Mathematical models; Operations; Support piles
• Geographic Terms: Arctic Regions
• Old TRIS Terms: Arctic engineering; Arctic operations; Ice forces on structures; Ice loads
• Subject Areas: Administration and Management; Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00025702
• Record Type: Publication
• Source Agency: Arctic Institute of North America
• Files: TRIS
• Created Date: Mar 28 1972 12:00AM