本研究是以試驗造波水槽設備探討規則波浪作用下海床土壤內部之反應特性,並與過去相關研究比較海床反應之異同及與土壤組成顆粒大小之影響。實驗結果初步顯示,在波浪作用下,本文所採用之土壤(中值粒徑d/sub 50/ =85.mu.m)其反應可規納為非液化,起始液化及連續液化三類特性反應,與Foda & Tzang(1994)所定義之三類特性反應比較發現,本文非液化反應紀錄無明顯之平均孔隙水壓上升現象,似乎隱喻沒有如沈泥所特有之表層液化作用,而起始液化反應記錄中沒有清楚之共振液化機制。此外本文試驗用土壤雖產生不完全類似沈泥土壤之反應,但當波浪液化後在液化海床上方均可憑肉眼觀察得明顯之懸浮漂沙現象,可進而作為研究波浪作用下懸浮漂沙與底床反應關連特性實驗設計之用。 This project is one of the 3 year-term sub projects of the Coordination Project entitled "Geomorphogic changes in Marine Areas". The present 2nd year project extends from previous study on the mechanism of wave-induced seabed instability aiming at classifying and clarifying instability mechanism in different seabed soils and wave fluidized seabed interactions. The research work consisted of experimental wave flume study and analyses on the characteristics of seabed soil responses. In this paper, a series of wave flume tests on seabed responses of a fine-grained cohesionless soil (d/sub 50/=0.85.mu.m) under wave actions were conducted to be compared with previous experimental results. Preliminary analysis on the pore pressure measurements showed three characteristic types of responses, defined as unfluidized, initially-fluidized and continuously fluidized, respectively. The comparisons with Foda & Tzangs' (1994) data immediately demonstrated that in present tests the measurements of unfluidized response did not display mean pore pressure build-up and those of initially fluidized response consist of no evident mechanism of resonance. These comparisons suggest the seabed responses of present fine-grained soil are slightly different from silty soil's responses, but by visual observations, sediment suspension were similarly clearly seen over the fluidized seabed. The results imply that it becomes feasible to further study the characteristics of correlation between wave-induced seabed response and sediment suspension in the laboratory.
Suspended sediment concentration