1999 Fiscal Year Final Research Report Summary
Study on influence of multidirectional waves on stability of breakwater
| Project/Area Number |
09650566
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
水工水理学
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| Research Institution | Tottori University |
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Principal Investigator |
MATSUMI Yoshiharu Tottori Univ., Faculty of Eng., Associate Professor, 工学部, 助教授 (00135667)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Stability of heads / Multidirectional waves / Wave directionality / Stability of armor stone |
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| Research Abstract |
This study complements the wave kinematical investigation on the performance of breakwater heads under uni (2D) and multidirectional (3D) waves. The measurement of velocity field on the heads under 2D and 3D waves was undertaken in the 3D waves basin, the characteristics of the velocity vectors on the heads under 3D waves were assessed by comparing them with the measurements under 2D waves. The sensitive zones of the initial damage in the head sections were evaluated by linking the velocity measurements with the static and dynamic formula for movement of armor stones on the heads. Furthermore, the theoretical approach to the velocity field on the breakwater was carried out to find the cause or mechanism of damages in the heads under multidirectional waves.
The velocity field over the heads under uni and multidirectional waves was only slightly different in the spread of direction of the velocity vectors under the experimental conditions adopted in this study. The prevailing directions of flows under 3D waves was approximately similar to those under 2D waves.
The equations of the critical velocity for armor stone movement in the head and trunk sections could satisfactorily explain the initial damage zones in the damage tests. The middle head section under 3D waves is the most sensitive zone for the initial damage. Under 2D waves, a more sensitive zone appears in back head section.
The stability weight of armor stones at the middle and back head sections under 3D waves becomes approximately 3.5 times heavier than the weight of armor stone in the trunk, which is calculated from the design formulas from Hudson and Van der Meer. Under 2D waves, the stability armor weight in the back head section becomes about 2.5 times value of weight of armor stone in the trunk.
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