摘要
天然河道蜿蜒曲折、主深槽常隨時間擺動，水流流向並不固定。橋墩保護工佈置於橋墩上游難免受水流攻角變化影響。
本文主要探討不同水流攻角對筐網結構物保護橋墩沖刷之影響，藉由改變筐網設置距離與高程，作一系列的討論： (1)沖刷歷程、(2)橋墩周圍底床高程、(3)筐網周圍底床高程、(4) 橋墩兩側底床高程的對稱性、(5)橋墩周圍最小與最大沖刷深度位置及(6)保護效果。另外，本文在不同水流攻角下，根據筐網對橋墩的保護效果探討筐網最佳佈置方式。
當水流攻角的增加時，各相關特性之試驗結果如下：(1)橋墩沖刷歷程沒有規律的變動趨勢；(2)橋墩周圍底床高程隨之下降；(3)筐網周圍底床高程在不同水流攻角彼此重疊，不易判別變動趨勢；(4) 橋墩兩側底床高程的對稱性具有臨界值，此臨界值為最不對稱的狀態；(5)橋墩周圍最小沖刷深度位置具有臨界值，此臨界值位於橋墩側方；最大沖刷深度位置則由橋墩側方移至橋墩迎水面；(6)筐網對橋墩的保護效果隨之降低。
根據試驗結果得知，筐網設置距離橋墩1倍橋墩直徑處、筐網底部設置於底床砂面上為本文試驗條件範圍內筐網最佳佈置方式。

ABSTRACT
The natural rivers are winding, the main channel is often swung with time, and it is not regular that the rivers flow into. The Pier Protection Structure to decorate and upstream on the pier and unavoidably influenced by change of angle of attack with flow.
This paper research into different angles of attack with flow influence as Against Pier scour of Penetrant Structure thing mainly, by change Penetrant Structure set up distance with height, act as a series of discussions. (1) Scouring processes, (2) Bottom bed height around the pier, (3) Bottom bed height around the Penetrant Structure, (4) Pier both sides symmetry in the bottom bed height, (5) Pier the minimum and maximum scour depth position and (6) protect. In addition, this paper is under different angles of attack with flow , research into the Penetrant Structure set up the way to the against pier scour result of bestly according to the Penetrant Structure .
As the increase of the angle of attack with flow , the result of the test of every relevant characteristic is as follows: (1) The pier Scouring processes the change trend without law of course ; (2) High downward thereupon of the bottom bed height around the pier ; (3) Bottom bed height around the Penetrant Structure overlaps each other on different angles of attack with flow, it is difficult to differentiate the change trend ; (4) Pier both sides symmetry in the bottom bed height has critical value , this critical value for the most asymmetric state ; (5) Pier the minimum scour depth position has critical value, this critical value lies in the pier side ; the maximum scour depth position is transfered from pier side to the pier met the surface of water ; (6) Reducing thereupon of protection result to the pier of the Penetrant Structure.
From the results of experiment, the Penetrant Structure sets up from the place of diameter of pier of a time of the pier and the Penetrant Structure bottom is set up the sand of the bed of bottom for the Penetrant Structure fixes up the way bestly in the experimental condition range of this paper.

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