- 學位論文
台灣河砂之剪力強度研究
Study on Shear Strength of River Sand in Taiwan
摘要
本研究是採用台灣主要河川的上游、中游及下游的天然溪砂為試樣，先以顆粒分析試驗，進行統一土壤分類，再以直剪試驗取得試樣的剪力強度參數，並嘗試將各試樣之均勻係數Cu及曲率係數Cd值與ϕ值繪成關係曲線。結果發現，各河川上游、中游及下游河砂的粒徑分佈非常近似，且皆屬於級配不良SP的砂；三者在疏鬆狀態時之摩擦角北部(基隆河)，約為27.7~25.6°之間，中部(濁水溪)及東部(宜蘭河)約為43.7~33；緊密狀態時，基隆河下游的摩擦角38°，中游 (35.8°)，上游 (43.2°)，濁水溪下游的摩擦角34.2°，中游 (41.22°)，上游 (43.98°)，宜蘭河下游的摩擦角44.27°，中游 (42.15°)，上游 (38.31°)；基隆河及濁水溪無論鬆散狀態與緊密狀態下的砂樣，Cd愈大則摩擦角愈小，而Cu愈大則摩擦角愈大。而宜蘭河在鬆狀態時均勻係數Cu與ϕ呈遞減關係；砂樣的Cu愈大則摩擦角愈小；在緊密狀態時Cd愈大則ϕ愈大。另由有效粒徑D10及滲透係數K反求經驗公式中的常數C，藉以了解顆粒大小對滲透係數的影響，得到台灣河砂的C為0.128。
並列摘要
The study of samples from the upstream, midstream and downstream of major rivers in Taiwan in this study. First, Particle distribution tests and Unified Soil Classification System are carried out to classify soils, and then shear strength parameters of the samples are obtained by direct shear tests, and each is attempted. The Coefficient of Uniformity Cu of the sample and the Coefficient of Curvature Cd are plotted against the value of friction angle ϕ. The results showed that the particle size distributions of river sands in the upstream, midstream and downstream of the rivers are very similar, and they all belong to the gradation poor sands SP. In the loose state, the friction angle in the Keelung River is about 27.7~25.6°, in the Zhuoshui river and in the Ilan River is about 43.7~33°; in the dense state, the friction angle in the downstream of the Keelung is 38°, Midstream (35.8°), Upstream (43.2°), Friction angle is 34.2° in the downstream of Zhuoshui river, Midstream (41.22°), Upstream (43.98°), Friction angle is 44.27° in the lower reaches of Yilan River, Midstream (42.15° ), Upstream (38.31 °); Keelung River and Zhuoshui river sand samples in both loose and dense state, the larger the Cd, the smaller the friction angle, and the larger the Cu, the larger the friction angle. In addition, the constant C in the empirical formula is inversely calculated from the effective size D10 square and the Permeability coefficient to understand the influence of the particle size on the permeability coefficient, and the C is 0.128 in Taiwan.