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標題: | 低塑性三元混合土壤之抗液化研究 Liquefaction Resistance of Low Plasticity Ternary Mixtures |
作者: | 林沂儒 Yi-Ju Lin |
指導教授: | 葛宇甯 Louis Ge |
關鍵字: | 動力三軸試驗,三元混合土壤,塑性指數,孔隙比,有效圍壓,抗液化強度, Cyclic triaxial test,Multeity Mixtures,Plasticity index,Target void ratio,Effective confining pressure, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 本研究使用石英砂、石英粉以及高嶺土作為混合土壤之材料,其細顆粒與粗顆粒之比例為6比4,透過改變石英粉與高嶺土之比例獲得不同塑性指數,以濕搗法重模試體,規劃試驗於試體孔隙比為0.860、0.747、0.705與有效圍壓80 kPa、160 kPa下,以相同的加載速率0.1 Hz進行動力三軸試驗,探討各變數對於混合土壤液化之影響。
結果指出,在不同塑性指數、相同孔隙比與有效圍壓下,土壤抗液化強度與塑性指數之關係呈曲線,液化強度與塑性指數關係以塑性指數為4作分界呈現相反之趨勢。此外不同塑性指數對於液化行為的表現也不盡相同,在當高嶺土於細顆粒含量中達到10% 時,部分試體會先達到單振幅軸向應變2.5% 之液化判定時機而非超額孔隙水壓為1。 無塑性土壤試體在孔隙比為控制變因下,土壤抗液化強度會與孔隙比成反比,且試體液化破壞後所排出之超額孔隙水體積隨著孔隙比越小而越少。 本研究另探討有效圍壓對於低塑性三元混合土壤抗液化強度之影響,控制試體於相同塑性與孔隙比的狀態,其試驗結果顯示在相同反覆次數作用下,混合土壤所需的反覆剪應力比將會隨著有效圍壓上升而增加,並且在增加其有效圍壓的同時也會造成有效圍壓影響因子的上升,代表有效圍壓增加時抗液化強度也會隨之增強。 Ternary mixtures consist of sand, silt, and clay. The study used silica sand, silica powder and kaolinite as materials for ternary mixtures. The proportion of coarse and fine grains is 6 to 4. Plasticity was adjusted by changing the proportion of silica powder and kaolinite to 0, 4, 8, 14. The specimens were remolded by the wet compaction method with void ratios of 0.860, 0.747, and 0.705. Testing was conducted at confining pressures of 80 and 160 kPa with loading rates of 0.1 Hz during cyclic triaxial tests. The effects of plasticity index, void ratio, and confining pressure of ternary mixtures on liquefaction resistance were explored. The results indicate that the relationship between plasticity index and liquefaction resistance displayed a V-shaped curve at the same void ratio and confining pressure. The relationship shows an opposite trend with a PI of 4 as the boundary. Also, specimens with different plasticity show different failure modes. In specimens with a certain PI value, the liquefaction triggering criteria is 2.5% single axial strain instead of 1 excess pore pressure (γ_u). For specimens without kaolinte, the void ratio and liquefaction resistance are inversely proportional. Denser soils exhibited higher liquefaction resistance and lower excess pore water discharge. The effect of effective confining pressure on the liquefaction resistance of low-plasticity ternary mixtures has also been discussed. The cyclic stress ratio is increased with effective confining pressure under the same plasticity index and void ratio, and the influence factor is as well. It means that liquefaction resistance increases with effective confining pressure. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88497 |
DOI: | 10.6342/NTU202302278 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 土木工程學系 |
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