河口砂州自然開削の実測・実験と解析

河口沙洲自然开挖实测、实验与分析

基本信息

批准号：
01550396
负责人：
SHUTO Nobuo
金额：
$ 1.41万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550396/
关键词：
River mouth Sand spit Flushing Beach process Sedimentation 標砂開削

项目摘要

(1) The sand spit at the mouth of the Nanakita River was flushed twice by floods. The water level measured upstream the river mouth showed quite similar time-variation in these two flushing processes : at the initial stage of floods, river water overflowed with a depth of several ten centimeters, and flushing was completed within 3 to 4 hours.(2) The k-epsilon turbulence model is applied to a rapidly varied flow over a two-dimensional sand bar. The numerical results are compared with the experimental data obtained by LDV. The water surface profile, the mean velocity profiles and the bottom shear stress are simulated reasonably.(3) The bedload formula of Meyer Perer-Muller is extended to include the effects of local slope and pressure gradient, by using the experimental results. The equation of motion is derived to describe the sand motion under non-equilibrium conditoin. The numerical computations based upon these relationships simulate very well the temporal change of the measured profiles of sand bars and corresponding variation of the water surface.(4) Equations of shallow-water theory and sediment movement in equilibrium condition are solved numerically by means of a finite difference method to predict flow field and topography change at a river mouth during flood. First, the comparison is made with the data of a model experiment. The predicted water surface profiles show excellent agreement with the experimental results.Second, the comparison is made with the field data measured at Nanakita River Mouth. It is found that the shape of the eroded cross section could not be predicted well. This is mainly due to the fact that the non-equilibrium condition of sand movement is not included in the present calculation.

（1）在纳纳基塔河口的沙子被洪水冲洗了两次。在这两个潮红过程中，河口上游测量的水位显示出非常相似的时间变化：在洪水的最初阶段，河水溢出，深度为几十厘米，在3到4个小时内完成了冲洗。）K-Epsilon湍流模型应用于二维砂杆上的迅速变化的流动。将数值结果与LDV获得的实验数据进行了比较。合理地模拟了水面曲线，平均速度曲线和底部剪切应力。（3）使用实验结果，将Meyer Perer-Muller的床载公式扩展到包括局部斜率和压力梯度的影响。运动方程是为了描述非平衡孔的砂运动。基于这些关系的数值计算很好地模拟了砂棒的测量曲线的时间变化以及水面的相应变化。（4）通过数值求解浅水理论和沉积物运动的方程预测洪水期间河口的流场和地形变化的有限差异方法。首先，与模型实验的数据进行比较。预测的水表面剖面与实验结果表现出非常一致的。发现无法很好地预测侵蚀的横截面的形状。这主要是由于当前计算中不包括沙子运动的非平衡条件。