本研究採用台灣彰化離岸的海床土壤進行重模試體，利用Stokoe型振柱儀器進行不同初始孔隙比（0.7、0.8與0.9）、飽和度（15%、30%、60%與100%）、細粒料含量（15%、30%與50%）在不同有效圍壓（20 kPa、80 kPa與320 kPa ）下的試驗，目的是分析不同情況下的剪力模數及阻尼比，深入了解土壤動態性質在不同狀態下會產生的變化。本研究使用共振柱低振幅試驗求取最大剪力模數，扭轉剪力試驗獲得特定剪應變下的剪力模數及阻尼比。
試驗結果顯示，隨剪應變增加，剪力模數會下降、阻尼比會上升。孔隙比、有效圍壓、細粒料含量、飽和度皆對剪力模數有影響，其中細粒料含量會受到飽和度影響而改變其強度趨勢。而孔隙比及有效圍壓下降都會使正規化剪力模數向左偏移。阻尼比的變化很小，參數中除了孔隙比，其餘三個因素皆會對阻尼比造成影響。阻尼比會隨有效圍壓下降、飽和度下降及細粒料含量上升而上升。

The main purpose of this research is to study the effect of the factors which are void ratios (e = 0.7,0.8 and 0.9), fines content(FC = 15%, 30%, and 50%), degree of saturation(S = 15%, 30%, 60%, and 100%), and confining pressure (Pc = 20 kPa, 80 kPa, and 320 kPa) on the dynamic properties of low plastic silty sands. The offshore subsoil in Changhua, Taiwan was selected for the study. To perform this study, the resonant column low-amplitude test was conducted to obtain the maximum shear modulus, the free vibration decay method acquired the viscous damping ratio, and the torsional shear test was used to obtain the shear modulus and hysteresis damping ratio under a specific shear strain.
Presented herein are shear moduli of various kinds of sands for shear strain of 10-6 to 10-2 which were obtained by utilizing a Stokoe-type resonant column apparatus and a torsional shear apparatus. The test results show that the shear modulus decreases and the damping ratio increase with increasing shear strain. The void ratio, saturation, effective confining pressure, and fine content all affect the shear modulus and damping ratio. But the content of fines will be affected by saturation and change its trend. The decrease in void ratio and effective confining pressure will shift the normalized shear modulus to the left. The decrease in void ratio and effective confining pressure will make the normalized shear modulus a leftward shift. The damping ratio is tiny variations. In addition to the void ratio, the damping ratio will increase with decreasing effective confining pressure, decreasing saturation, and increasing fine content.

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