海岸堤防・離岸堤・人工リーフの波浪による洗掘の対策実験

概要

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Counter measures against scouring are investigated at the foot of the coastal sutructures by model tests. The sea bed is fine sand and the shape of the bed is shown by Fig.1. The foundation of the coastal structures was made on the bed. As shown by Fig.2, blocks protectiong the toe of the fundation were placed on the level fo the bed, blockeds for sucking proteciton of stone were set behind them, and stone was packed dowm backward. The water depth is 17.7cm on the level of the bed, and 8.7cm on the crowm of the fundation. The bed's slope ahead of the blocks is cotθ=3.5 and the water depth is 42.7cm at the end of the slope. The following shows the test cases: Case 1: Blocks are directly places on the bed. Case 2: Steel frame is set on the bed and blocks are arranged on the frame. Case 3: Permeable sheet instead of the frame os spread on the bed. Case 4: Weight is added to the toe of the sheet. The model tests were done by regular wave, the wave height is H=10cm and the wave period is T=2.5s. According to the result of tests, it is difficult to pretect the foundation from the scouring by wave. However, the progress of scouring can be delayed. In these tests, Case 2, that is, "Frame Works" is more desirrable than any other Case for scouring and stability of the blocks.
2005-03-25