| Project/Area Number |
18560509
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
水工水理学
|
|---|
| Research Institution | Kobe City College of Technology |
|---|
Principal Investigator |
TSUJIMOTO Gozo Kobe City College of Technology, 都市工学科, Professor (10155377)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HOSOYAMADA Tokuzo Nagaoka University of Technology, 環境建設系, Associate Professor (70262475)
KAKINOKI Tetsuya Kobe City College of Technology, Associate Professor (50353298)
UNO Kohiji Kobe City College of Technology, Lecturer (00435439)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
|
|---|
| Keywords | beach profile / mixed sediment / filter laver / irregular wave / フィルター層 / 画像解析 / 強熱減量 / 歩行性 |
|---|
| Research Abstract |
Artificial beaches with a gravel filter layer have been constructed based on the fail-safe concept in Japan since a sinking accident of artificial sand beaches has occurred. As shown in Fig.1, many types of gravel are sometimes discharged from the sea bottom after stormy weather, and subsequently the sand beach could change into the mixed sand beach with gravel. Therefore, a decrease of safety or stability on them is major concern. But no design methods are currently available for artificial beaches with a gravel filter layer. The objective of this study is to propose the optimum condition for a gravel filter layer ; assess the installation depth and length through experiments in a water flume, also develop a numerical approach to estimate run up height over the slope with a gravel filter layer.
Focusing on invertibility of beach profiles, safety of coastal beaches with a filter layer was studied experimentally and theoretically. The following conclusions were obtained :
(1) A filter lay
… More
er could promote the deposition of sediment and reduce the erosion of sediment. By setting the onshore edge of a filter layer in the position of shoreline at H.W.L., the above-mentioned process would be more promoted.
(2) The filter layer does not have the tendency to obstruct the stability of beach profile i.e. the development of an offshore bar, or the sudden changes of water depth near the shoreline.
(3) Though invertibility of beach profiles depends strongly on the tidal level, it was found through analytical results of the spatial spectrum that a filter layer would promote invertibility.
(4) The gravels in a filter layer are not exposed to the bed due to changes of beach profiles. Even if exposed, the erosion of beach profiles could not be promoted easily.
(5) The flow velocity in a filter layer was about 10% of that in the water region, while the wave phase variations of both are nearly same.
(6) An increase in permeability of a filter layer does not necessarily cause a decrease of the runup height. Less
|
