Exoerimental study on erosion rate of cohesive sediment and the attempt toward direct measurement of it in revers.

研究了天然沉积的软质粘性泥沙的冲刷过程。通过系统地设定试验条件，进行了一系列的试验，以评价封闭管道中自来水的冲刷速率。测试样品由硅砂、粘土和水的混合物组成，其组成被设置为可变的。控制这一过程的主要因素被发现是粘土含量比（粘土与总沉积物的重量比），水含量比（水与粘土的重量比），和摩擦流速，水温，硅砂的大小和干湿历史。定量地评价了这些参数对冲蚀率的影响。并根据试验结果推导了冲蚀率公式。并在一定程度上探讨了这一过程的机理。在此基础上，研制了真实的河流冲刷率便携式测量系统，并进行了一系列的冲刷试验，验证了冲刷试验的有效性。

The erosion process of soft cohesive sediments, which were deposited naturally on a river bed, is investigated in this study. Extensive series of experiments, conditions of which were set systematically, were conducted to evaluate the erosion rates by running water in a closed conduit. Test samples consisted of a mixture of silica sand, clay and water, the composition of which was set to be a variable. The main factors which govern this process were found be the clay content ratio (the weight ratio of clay to the total sediment), the water content ratio (the weight ratio of water to the clay), and a frictional velocity of flow, a water temperature, the size of silica sand and the dry-wet history. The effects of these parameters on the erosion rate were evaluated quantitatively. The erosion rate formula was also derived on the basis of experimental results. Also, the mechanism of this process was examined and made clear to a certain extent. In addition to these fundamental studies, the portable measuring system of erosion rate in a real river was developed, and a series of measurement was also conducted confirm the validity of this erosion test.