Laboratory indentation tests with thick freshwater ice. Vol. 1

A series of ice indentation tests was carried out in a small ice basin between October 1989 and February 1990. The tests were performed by horizontally loading a floating sheet of columnar grained freshwater ice with an indenter which was installed in front of a single-degree-of-freedom structure. The maximum indentation force available was 400 kN. The main concern was on the inplane and inclined indenters and velocities of 10 to 80 mm/s. The other parameters varied included aspect ratio, ice thickness and the dynamic parameters of the structure. The quantities measured were forces, displacements, accelerations, strains and local pressures. Two video cameras and a high speed camera were used to record visual observations. Of the 77 tests made the report presents 11. The time histories of the other tests are given in volume II. The interaction was found to be cyclic. The structure stood still or moved slowly forward during the loading phase and surged forward extruding the crushed ice when the force dropped. The maximum force level was limited by the formation of vertical or circumferential shear cracks symmetrically on both sides of the horizontal center line of the ice sheet. They reached across the whole contact face. The remaining ice wedge was crushed. The pressure distribution in this phase was linelike.