本文利用細砂質土壤( d50 = 0.078mm )，降低試驗水深至35cm和25cm進行造波試驗，以探討水深降低時海床反映和懸浮漂砂濃度剖面。試驗時於近底床上方等間距架設 5 支光學式濃度計，並於其下海床內部定位置處架設 5 支孔隙水壓計，同時量測懸浮漂砂濃度及孔隙水壓。孔隙水壓量測結果顯示，本細砂質土壤在降低試驗水深之規則波與規則波群作用下有部分起始液化，部分起始、部分連續液化，連續液化及非液化四種反應。起始液化反應之淺層與部分起始、部分連續液化之深層有共振放大現象產生。一般而言，波浪尖銳渡比淺水參數對海床液化還要具有代表性，第一次發生液化反應之試次其波浪尖銳度也會跟著降低。海床液化時，隨著起始液化深度的增加，海床上方濃度值有明顯上生現象，且當液化深度開始降低，濃度值亦隨之降低。波群發生部分碎波時，底床顆粒懸浮現象較激烈，連續液化反應可量到高濃度值。懸浮漂砂濃度剖面於液化階段以指數和對數分佈來描述能得最合適的趨勢線。

　　In this thesis a sandy soil with d50 of 0.078mm was adopted in laboratory flume tests for investigating soil fluidization responses and overall suspended sediment concentration profiles in shallower depths. Both monochromatic wave and regular wave group conditions were generated and the resulting depth profiles of sediment concentration with 5 optical probes above and pore pressures with 5 transducers inside the bed were studied. Comparisons with previous experimental studies clearly show that under monochromatic waves and regular wave groups the present sandy seabed displayed typical fluidized responses termed as partially-initially fluidized, partially initially/continuously fluidized and continuously fluidized as defined in previous studies, respectively. Even in partial soil fluidization there were resonant pressure amplitude amplification and rapid mean pore pressure build-up, particularly in upper soil layer. In wave-group tests, step build-ups of the pore pressure typically illustrate that further fluidization usually occurred after the large wave actions in each group. It is found that soils with lower permeability and under steeper waves are more likely to be fluidized in the first run. In general, the depth profiles of suspended sediment concentration near above the fluidized beds approximate either a logarithmic law or an exponential law under the generated wave conditions.

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