臺灣博碩士論文加值系統

本研究之主要目標在探討固定底床坡度、波向角，及相同的波浪條
件( 入射波高、週期) 下，改變突堤長度以及間距比，探討這兩項變數對
於沿岸輸砂量、突堤上下游側淤砂量與兩突堤中間之堆砂量之影響。

研究結果顯示，沿岸輸砂率在垂直海岸方向分佈大部份集中於 X/Xb=
0.55~1.2 約在X/Xb≒0.75最大，突堤長在 B/Xb＜0.4時突堤之阻砂效果
不彰，當 B/Xb＞0.4阻砂效果較為明顯。突堤上游側水面上之堆砂體積與
面積均隨著突堤長度之加長而增加，大約在堤長與碎波距離比( B/Xb
)為0.94達最大值，至於突堤上游側水面上加水面下之堆砂體積則在B/Xb
＝0.7 時達最大值。對突堤上游側之灘線前進量而言，在 B/Xb＜0.94 前
突堤上游側之無因次灘線前進量隨B/Xb的增加而逐漸增加，待B/Xb＞0.94
以後隨B/Xb的增加無因次灘線前進量則趨於穩定。就兩突堤中間水面上堆
砂量而言，當堤長為62.4公分或83.2公分時，在突堤間距比G/B＝2.5的情
況下可得最大之水面上堆砂體積，在突堤間距比G/B為2.0∼3.0 時，則有
較大之堆積面積。當突堤間距固定為124.8cm 時，兩堤中間水面上之堆砂
體積與面積約在 B/Xb=0.54時可得最大值。大致上隨著突堤長度與碎波距
離比值的增加，突堤下游側水面上加水面下之堆砂體積、水面上之堆砂體
積與面積其損失有增加之現象。

The main purpose of this research was study under the
conditions of steadyslope of original shoreline﹑the angleof
incidence between wave and shoreline,and same waveconditions
(wave height﹑period of wave.) By changing the lengthof groin
and the interval ratio, the influences ofthis two parameters on
long-shore sand transport rate, sand accumulation at upcoast
and downcoast of thegroin, and sand volume between two groins
were studied. The result showed that
longshore sand transport rate in the direction of vertical
shoreline is generally found to distributed between the range of
X/Xb=0.55~1.2 with the maximum value at X/Xb= 0.75. The
impedance of sand driftingwas less efficient, when the length of
groin was at B/Xb < 0.4, however,there was obvious performance
when B/Xb>0.4. At the upcoast of groin,the sand volumeand the
accumulated area above the water level increased with the
increase of groin length, and reached maximum value when the
ratio of its length and the distance from shore line to break
point (B/Xb) around 0.94. The sand volume atthe upcoast of groin
reached the maximum value when B/Xb = 0.7. About the for-warding
shoreline at upcoast of the groin, before B/Xb< 0.94 the
dimensionlessforwarding of upcoast shoreline increased with the
increase of B/Xb, and untilB/Xb>0.94 the increasing become
steady.About the sand volume above water levelbetween two
groins, when the length of groin is 62.4 cm or 83.2 cm, maximum
value under the condition of the interval ratio G/B=2.5 was
achieved. However,when the groin interval ratio G/B between
2.0~3.0, the larger accumulated areawas obtained. When we set
the interval of groin at 124.8 cm, the sand volume and the
accumulated area above the water level reached the maximum value
when B/Xb=0.54. In general, the losses of the following three
values: the sand vol-ume at downcoast of the groin﹑the sand
volume and the accumulated area above the water level at
downcoast of the groin,would increase with the increasingratio
of the length of groin and the distance from the shoreline
to breakpoint.