白雲母-砂土之剪力強度特性研究

An experimental study of shear strength characteristics of Muscovite-Sand Mixtures

林國偉(Kuo-Wei Lin)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200126

摘要

文獻資料顯示台灣砂土中可能含有雲母礦物，而在雲母質砂土的研究上大多著重於壓縮性，對於雲母質砂土的剪力強度特性很少被探討。本研究針對白雲母混合砂土試樣之剪力強度進行探討，利用直接剪力試驗儀來測得砂土之剪力強度，砂土試樣包括麥寮砂及渥太華砂，並分別加入不同含量之粗、細白雲母，得到不同白雲母含量情況下之砂土內摩擦角，以提供工程設計之參考資料。
　　研究結果顯示，原樣麥寮砂試樣於乾燥狀態下乾單位重(12.94kN/m3，Dr=11.09%)比飽和狀態略高約0.3kN/m3。乾燥狀態下粗白雲母含量增加5%~10%時，乾單位重減少約1.5kN/m3，含量高於10%後每增加5%，乾單位重減少約0.5kN/m3；細白雲母含量增加5%時乾單位重無明顯變化，含量高於5%後每增加5%，乾單位重減少約0.5kN/m3。飽和狀態下白雲母含量由10%增至30%，含粗白雲母之乾單位重比含細白雲母之乾單位重要低約2.6 kN/m3 ~ 3 kN/m3。
　　渥太華砂乾燥狀態下乾單位重(15.52kN/m3，Dr=18.51%)比飽和狀態略高約0.3kN/m3。乾燥狀態下粗白雲母含量增加10%時，乾單位重明顯減少約3.5kN/m3，含量高於10%後每增加10%，乾單位重減少約1kN/m3；細白雲母含量增加10%時乾單位重無明顯變化，含量高於10%後每增加10%，乾單位重減少約1.5kN/m3。飽和狀態下白雲母含量由10%增至30%，含粗白雲母之乾單位重比含細白雲母之乾單位重要低約2.6 kN/m3 ~ 3.3 kN/m3。
　　在乾燥狀態下原樣麥寮砂混合細白雲母試體之線性迴歸內摩擦角比混合粗白雲母試體高約0.8°~1.9°；每增加5%細白雲母線性迴歸內摩擦角便減少0.5°~1.2°，而含粗白雲母之試體則減少0.3°~1.5°。在飽和狀態下原樣麥寮砂混合粗或細白雲母試體之線性迴歸內摩擦角幾近相同，白雲母含量每增加10%線性迴歸內摩擦角減少1.1°~3.5°。
　　在乾燥狀態下渥太華砂混合細白雲母試體之線性迴歸內摩擦角比混合粗白雲母試體高約1.7°~2.5°；每增加10%細白雲母線性迴歸內摩擦角便減少0.6°~1.7°，而含粗白雲母之試體則減少1.2°~3.1°。在飽和狀態下渥太華砂混合粗白雲母試體，白雲母含量每增加10%線性迴歸內摩擦角減少1.3°~4°；混合細白雲母試體，白雲母含量每增加10%線性迴歸內摩擦角減少1.4°~2.2°。

關鍵字

砂 ； 白雲母 ； 直剪 ； 剪力強度

並列摘要

According to the literature, sands in Taiwan could contain mica particles. Most researches on micaceous sand focused on compressibility, and shear strength characteristics of the micacous sand are still rarely explored. This study explored the shear strength of muscovite-sand mixtures. Mailiao sand and Ottawa sand were used with different contents of coarse or fine muscovite to prepare direct shear test specimens to measure shear strength. It is hoped that the results will be useful for engineering design involved with micaceous sand.
Test results show that dry unit weight of the Mailiao sand in dry state (12.94 kN/m3, Dr=11.09%) is slightly higher than that in the saturation state by about 0.3 kN/m3. When the coarse muscovite content increases from 5% to 10% in dry state, the dry unit weight decreases by about 1.5 kN/m3, and thereafter it decreases by about 0.5 kN/m3 for each 5% increase. When the fine muscovite content increases 5%, the dry unit weight does not change, and thereafter it decreases by about 0.5 kN/m3 for each 5% increase. The dry unit weight of saturated coarse muscovite-Mailiao sand mixtures is lower by about 2.6、3.0、or 3.0 kN/m3 than that of fine muscovite-Mailiao sand mixtures for muscovite contents 10%、20%、or 30%, respectively.
　Dry unit weight of the Ottawa sand in dry state (15.52kN/m3, Dr=18.51%) is slightly higher than that in the saturation state by about 0.3 kN/m3. When the coarse muscovite content increases by 10% in dry state, the dry unit weight decreases by about 3.5 kN/m3, and thereafter it decreases by about 1 kN/m3 for each 10% increase. When the fine muscovite content increases 10%, the dry unit weight does not change, and thereafter it decreases by about 1.5kN/m3 for each 10% increase. The dry unit weight of saturated coarse muscovite-Ottawa sand mixtures is lower by about 2.6、3.2、or 3.3 kN/m3 than that of fine muscovite-Ottawa sand mixtures for muscovite contents 10%、20%、or 30%, respectively.
In dry state, the linear regression internal friction angle for the fine muscovite-Mailiao sand mixtures is higher by about 0.8° to 1.9° than that for the coarse muscovite-Mailiao sand mixtures. For each 5% increase in muscovites contents, the friction angle decreases by 0.5° to 1.2° for the fine muscovite and by 0.3° to 1.5° for the coarse muscovite. In saturated state, the linear regression internal friction angle for the muscovites-Mailiao sand mixtures are nearly the same, and it decreases by 1.1° to 3.5° for each 10% increase in muscovite content.
In dry state, the linear regression internal friction angle for the fine muscovite-Ottawa sand mixtures is higher by about 1.7° to 2.5° than that for the coarse muscovite-Ottawa sand mixtures. For each 10% increase in muscovites contents, the friction angle decreases by 0.6° to 1.7° for the fine muscovite and by 1.2° to 3.1° for the coarse muscovite. In saturated state, the linear regression internal friction angle decreases by 1.3° to 4° for coarse muscovite-Ottawa sand mixtures and by 1.4° to 2.2° for fine muscovite-Ottawa sand mixtures for each 10% increase in muscovite content.

並列關鍵字

Sand ； Muscovite ； Shear Strength ； Direct Shear

參考文獻

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