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On the Interactions of Waves and Fluidized Cohesionless Sea Bed (III)
|Contributors: ||NTOU:Department of Harbor and River Engineering|
Wave;Interaction;Cohesionless sea bed
|Issue Date: ||2011-06-29T01:37:16Z
|Abstract: ||摘要:本研究以線性疊加方式所得的規則波群為入射條件，應用斷面造波水槽進行試驗研究，探討所引致的底床液化反應之特性。試驗材料採用中值粒徑d50= 0.078 mm的細砂，試驗量測項目包括孔隙水壓及自由水面的時間變化。從兩回合代表性的試驗結果顯示，規則波群的孔隙水壓反應，如同簡諧波的結果，亦可分成非液化、起始液化及連續液化三種類型，且波壓歷時變化也有群性之型態。從液化試次之階段性孔隙水壓抬升過程中，可清楚發現海床液化範圍從淺層土壤逐漸擴及深層土壤；而藉由瞬間波能歷程之比對，更進而發現液化之啟動大都是發生於同一波群中較高波浪作用後，此特性未曾從過去簡諧波浪試驗中獲得證實。|
abstract:This experimental study applied wave groups from two linearly superposed harmonic waves to act upon two fine sandy seabeds in a wave flume setup. It was aimed at studying the fluidized responses for sandy soils with d50= 0.078 mm respectively. The measurements consist of depth profiles of temporal variations of pore pressures and free surface. From two typical sets of data the analysis shows that three response types of unfluidized, initially fluidized and continually fluidized are found to be similar to those induced by monochromatic waves, but the temporal variations of pore pressure clearly demonstrate grouping phenomena. In these fluidized responses, the process of stepping rises of mean pore pressure further indicate that seabed soils were gradually fluidized from shallow layers to deeper layers. Moreover by comparing with the instantaneous wave energy history, the stepping rises were most likely triggered by the higher waves in the same wave group. This feature has never been confirmed in past monochromatic-wave tests.
|Appears in Collections:||[河海工程學系] 研究計畫|
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