細顆粒含量對於粗細砂混合物之力學性質的影響

Effects of Fines Content on the Mechanical Properties of Binary Mixtures

葉憶萱(Yi-Hsuan Yeh)

指導教授 ： 葛宇甯

國立臺灣大學/工學院/土木工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803623

摘要

現地土壤是由多種不同種類及大小的顆粒所組成，土壤中的顆粒排列及其行為相當複雜，因此土壤排列的相關議題已經被討論了數十年。許多研究將土壤組成簡化，探討二元或三元混合物之行為。砂土的特性主要受到顆粒間的排列所影響，所以對於砂土混合物來說，顆粒排列的情形對其土壤的力學性質有顯著影響。土壤混合物的組態會因為顆粒的形狀、顆粒的尺寸及其分佈曲線和沉積方式而有所不同。
本研究主要探討粗細砂之二元混合物中，細顆粒含量對其排列情形及力學性質之影響。使用的粗細顆粒混合物，由兩組不同尺寸的越南石英砂組合而成，這些特定尺寸的顆粒按照不同比例均勻混合，以量測混合物的最大及最小乾單位重。
為了觀察此二元混合物的材料特性，我們改變混合物的細顆粒含量(FC)，從0-100%。並在乾燥的情形下，對混合物進行單向度壓密試驗及直接剪力試驗。混合物的最大和最小孔隙比、壓縮特性及剪切行為會與細顆粒含量進行比較。此外，粗顆粒與細顆粒之間的粒徑比，也是本研究另一個關注重點。
實驗結果發現，此二元混合物之最大及最小孔隙比也會隨細顆粒之含量變化而改變。壓縮指數在FC=15%及85%時具有最大值，而此細顆粒含量下之摩擦角則最小；反之，摩擦角之最大值發生在FC=35-50%之間，並發現當粒徑比較大時，摩擦角的最大值也較大。

關鍵字

二元混合物 ； 細顆粒含量 ； 最大及最小孔隙比 ； 壓密試驗 ； 直接剪力試驗

並列摘要

In-situ soils are composed by multiple sizes and different types of particles. The arrangement of particles in the soil and its behavior may be quite complicated. The issues of soil packings for soil mixtures have been puzzled for decades. Hence, plenty of studies have been done to investigate on binary or ternary packings.
The behavior of sand is mostly dominated by fabric of the particles, and the packing of the particles have a significant impact on the mechanical properties of the soil for binary mixtures. The configurations of soil mixtures can be determined by the shapes, the sizes of particles, the distribution curve, and the way of deposition.
In this study, the main concern is the effect on fines content of coarse-fine granular mixtures. The mixtures are composed by two different sizes of coarse particles and finer particles. Sand particles with specific grain sizes are mixed to measure the maximum and minimum void ratio (e_M^max and e_M^min) in different contents of coarse sands and fines.
To observe the characteristics of binary mixtures, the compression and the direct shear test are also conducted on a number of different coarse-fine granular mixtures constituted at different fines content ranging from 0 to 100%. The void ratio, compression characteristics, and the shear strength of soil mixtures are compared with the content of fine particles. Moreover, the particle size ratio is also an important concern in this study.
The experimental results show that the maximum and minimum void ratios for the binary mixtures vary with the content of fines. In addition, there are two peak values of compression index when the fines content is at 15% and 85%; on the contrary, the friction angle is lowest under these fines content. And it is also found that when the particle size ratio is larger, the maximum friction angel occurs in higher fines content.

並列關鍵字

coarse-fine granular mixtures ； fines contents ； maximum void ratio ； minimum void ratio ； compression test ； direct shear test

參考文獻

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