一様湾曲水路における岩盤河床の侵食及び水成地形に関する実験的研究  [in Japanese] EXPERIMENTAL STUDY ON BEDROCK INCISION AND BED CONFIGURATION IN ANNULAR FLUME FLOW  [in Japanese]

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Abstract

近年,多くの河川において基盤岩の露出による岩盤河床の侵食が深刻な問題となっている.岩盤河床の侵食は流砂の摩耗現象により引き起こされるため,河床上の砂礫堆積箇所と基盤岩の露出箇所を知ることは岩盤河床の侵食を考える際に重要となる.二次流により内岸で砂礫の堆積,外岸で基盤岩の露出が見られる湾曲部においては,ある特徴を持った岩盤河床の侵食が発生すると予測できる.<br> 本研究では,湾曲部における岩盤河床の侵食に着目し,一様湾曲水路を用いた室内実験を行うことで岩盤河床の侵食を再現した.そして,湾曲部における岩盤河床の侵食発生箇所及び河床変化の動態についていくつかの特徴を観測することができた.本論文では,実験結果とその特徴について報告する.

 Degradation of exposed bedrock takes place in many rivers worldwide, posing problems of current high interest for river management. Erosion in bedrock rivers is often caused by abrasion from moving sand particles, which is directly linked to the distribution of the alternating zones of exposed bed rock and bed covered with sediment. Erosion by abrasion is active only in a portion moderately covered with sediment. Where there is no sediment and bedrock is completely exposed, no abrasion takes place. And where the bed is fully covered with sediment, no abrasion takes place as well because of the cover effect of the sand.<br> In the present work, we study experimentally the occurrence of bed degradation in an annular covered flume flow with a simulated bedrock. In curving bedrock channels, due to secondary flow, sand accumulates in the inner bank while the bed is exposed in the outer bank. In the experiment, patterns of topo- graphic changes along the bed could be observed. We correlate the experimental results with expected flow patterns and erosion processes.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 73(4), I_847-I_852, 2017

    Japan Society of Civil Engineers

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