| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 86 === 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.
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