Influence of bedding orientation on the anisotropy of hydraulic conductivity in a well-sorted fluvial sediment

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• 作者：Dong-hui CHENG^a ; Xun-hong CHEN^b ; ^{xchen2@unl.edu} ; Ai-di HUO^c ; Min GAO^d ; Wen-ke WANG^e
• 关键词：Cross bedding ; Hydraulic conductivity ; Anisotropy ; On-site permeameter test ; Fluvial sediment
• 刊名：International Journal of Sediment Research
• 出版年：2013
• 出版时间：March, 2013
• 年：2013
• 卷：28
• 期：1
• 页码：118-125
• 全文大小：1124 K

文摘

The paper describes a permeameter test method for determination of the hydraulic conductivity (K) along multi-directions in fluvial sediments with cross beddings. Unlike existing in-situ permeameter methods that determine hydraulic conductivity for submerged streambeds, our method was intended to measure hydraulic conductivity of exposed streambeds or fluvial sediments. The method was applied to the Wei River, Shaanxi Province, Central China for characterization of the anisotropy of K in a well-sorted fluvial sediment. The results illustrated that even in well-sorted sediments, cross-bedding and sediment fabrication (or texture) can lead to varied K values along different measurement directions. The K value was the largest along the dip direction (or the major direction) that is parallel to the orientation of cross bedding and the smallest in the direction perpendicular to the bedding (or the minor direction). The K value in a given direction between the major and minor direction often fell in the range bounded by the K values in the major and minor directions. The anisotropy ratio of K (the ratio of K value between the major and minor directions) in two trenches for this well-sorted fluvial sediment was up to 1.14 to 1.23, respectively. Our results also demonstrated that even for well-sorted sediments, the K values between two sampling points only about 10 cm apart can differ. It is clear that the K distribution strongly correlates to the bedding orientation.