Medium-scale laboratory investigation of the effect of confinement on ice rubble strength and failure behavior

Understanding the deformation and strength of ice rubble is key to estimating ice ridge loads on ships, offshore structures and subsea infrastructure. Medium-scale punch tests were conducted at C-CORE's Cold Room facility to measure and observe the strength and failure behavior of freshwater ice rubble. A custom-built punch box measuring 3.05 m in length and 0.94 m in width and height was used to perform the tests. The box walls were made from Plexiglas so that failure mechanisms could be observed. Ice rubble beams of nominal thickness 50 cm were produced by placing randomly sized ice pieces into the punch box, filled with water at its freezing tem-perature. Beams were left for a period of 4 h to consolidate under vertical confining pressures ranging from 0 kPa to 40 kPa. The ice rubble beam was deformed by pushing a platen vertically downwards though the center of the beam until failure. Results showed that the failure behavior of the ice rubble beam was controlled by the degree of freeze-bonding/sintering between the blocks, which significantly increases with applied confinement.