CRITICAL RUN-UP HEIGHT ON THE SEA WALL

Akira Seyama, Akira Kimura

Abstract


This study aims at clarifying the difference between irregular and periodic wave run-ups on a slope or a sea wall. Since hydraulic phenomena on a slope are the induced result of an interaction between a running up wave and a back-wash. The run-up height, therefore, has to be investigated in terms of a back-wash properties in addition to run-up wave properties. The experiments which are so designed that waves can run up on a slope without meeting back-wash, were conducted to evaluate the back-wash effects. The relative run-up heights K /HQ of periodic waves in these experiments reached up to about two times as high as those of periodic waves which have the same steepnesses. The run-up heights of irregular waves on a slope were also investigated experimentally. There are no clear relations between R_/HQ and HQ/LQ as those for periodic waves ordinary observed, and they distributed widely. The upper-most value of RJ-/HQ in the distribution for any HQ/LQ was almost equal to the value in the above experiment. The uppermost (critical) relative run-up heights RJ-/HQ for the given HQ/LQ and slope may exist. The differences between the critical and ordinary run-up height of periodic waves on the sea wall were also experimentally investigated. The difference is prominent when a sea wall is set onshore from the shore-line. It reaches up to about 4 times when a sea wall is set a little on-shore from the shore line. Some statistical discussion on the probability of the situation in which the critical run-up may be brought about is given at the last part.

Keywords


sea wall; run up; critical height

Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.