(1)The maximum impact ice force occurs within 7 msec after collisions, because the ice floes collide with the structure at a high speed. This showed that a group of ice floes in motion due to waves rarely generate impact ice forces simultaneously, and that it is appropriately conservative for design purposes to consider that the impact ice force acts on a structure at points approximately every 4 meters of its length.
(2)When the momentum of the ice floe is small, the maximum impact ice force increases as the momentum increases. However, the maximum impact ice force is constant above a certain value of the momentum. This is supported by the results of this experiment and by the field test by Neill5).
(3)The theoretical area of contact between the ice floe and the structure when the maximum impact force occurs, multiplied by the unconfined compressive strength of sea ice (σ c) is the ice force. This ice force is almost equal to the maximum impact ice force.
(4)We estimated the impact ice force when ice floes run up onto the shore due to tsunamis and collide with the gate of a sea embankment.
References
1)Saeki, H., Takahashi, Y. and Mitani, T. Experimental Study on the Mechanism of Sea Ice Running up onto the Shore due to Tsunamis, Proc. of Coastal Engineering, Vol. 41, pp 796-800, 1994.
2)Takahashi, Y., Katayama, A., Hanada, M., Saeki, H. and Yamashita, T.: Experimental Study on the Mechanism of a Group of Ice Floes Running up onto the Shore due to Tsunamis, Proc. of Coastal Engineering, Vol. 42, pp 1241-1245, 1995.
3)Kunimatsu, S., Hara, F., Takahashi, Y., Saeki, H., Enoki, K. and Imaizumi, A.: study on the Size of Drift Ice at the Okhotsk Sea Coast of Hokkaido, Proc. of Civil Engineering in the Ocean, Vol. 9, pp 95-100, 1993.
4)Sakai, Y., Takahashi, Y., Mitani, T. and Saeki, H.: Experimental Study on the Velocity of Ice Floes Overtopping the Breakwater, Proc. of Cold Region Technology Conference, Vol. 9, pp 99-106, 1993.
5)Neil, C. R.: Ice Pressure on Bridge Piers in Alberta, Canada, Proc. IAHR Ice Sympo., 1970.
6)Saeki, H., Abe, 5., Nomura, T., Ono, T. and Ozaki A.: Study on Ice Pressure Acting on Coastal Structures (4), Proc. of Coastal Engineering, Vol. 25, pp 315-318, 1978.
