| Title | Three-dimensional characteristics and prevention mechanisms of scour at the head of a breakwater (3/4) |
| Dept | Transportation Technology Research Center |
| Year | 2016 |
| Month | 3 |
| Price | |
| Summary | The effect of wave-current and fluid-structure interaction on the offshore structures may erode around the seabed, which causes damage to or collapsing of the structures. Moreover, seabed topography near the end of the breakwater could be eroded by the contraction scour. In Taiwan, Taichung Port and Mailiao Harbor were cases concerning seabed erosion and scour near the breakwater head. As with the instance of Mailiao Harbor, the design depth in the entrance that closes to the north breakwater head was -22m. According to current sounding surveys of topography, there is a 500m x 100m deep pit with the maximum sounding of -48m near the breakwater head, which has been scoured approximately -26m. Although seabed erosion and scour near the breakwater head has become a serious threat to breakwater structures and the safety of navigation, the reasons and mechanisms that caused the erosion are still unknown. Therefore, there is an urgent need for further observation, research, simulation and verification in order to make effective prevention strategies and construction methods.
The main research objects in the third year of the four-year project regard Taichung Harbor and Mailiao Harbor. The main works contain: the search and literature analysis on the erosion of the seabed topography, detection and measurement of the seabed scours, site observation and analysis of waves and currents of the breakwater heads of these two ports respectively. Simulations of the tidal current distribution around the head of breakwater by using numerical model and physical model are also performed. Hydraulic test in Mailiao Harbor is given priority to, with geometric model 1/100 scale topographic change of the typhoon wave, slightly deposited in back of the breakwater, about 200 m away from the breakwater head for slight erosion, sedimentation change is not obvious. But overall topography changed little; base of breakwater is quite stable. With different scale test of topographic change, enlarging wave height and lower water elevations for typhoon waves, the results showed slight sedimentation at back of breakwater. Comprehensive experimental results of various conditions, found that when the N-direction of typhoon wave act on at west-breakwater of Mailiao Harbor lead to a phenomenon of erosion hold at southwest side of breakwater, and the scouring hole is consistent geographically. This project focused on the field surveys, hydraulic test and numerical simulations to predict the impact of scouring around a head of breakwater. The results of the study may help to reduce the collapse of marine structures and the navigational risks, make sure that the port operates normally. |
| Post date | 2016/05/09 |
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