【作者】 曾乐；

【导师】 王义刚； 夏云峰；

【作者基本信息】 河海大学 ， 港口、海岸及近海工程， 2007， 硕士

【摘要】 河工模型试验仍然是各种水利工程决策与优化时的主要研究手段，但河工模型试验中时间变态的问题一直得不到很好的解决。目前通常的做法是采用河床冲淤时间比尺而放弃水流运动时间比尺，以尽可能地保持河床冲淤的相似性，但这样做的结果将在一定程度上导致河道沿程水位、流量、含沙量以及河床冲淤量等的偏离，尤其是在受潮汐影响较大的河口地区，其影响程度尚未十分明了。本文利用一维非恒定水沙数学模型对数值水槽以及实际地形进行三种不同时间变态率的对比试验，通过比较原模型沿程水位、流量、含沙量以及冲淤量等物理量的差异分析时间变态对水流、泥沙运动的影响及影响因素并提出初步的校正措施，主要研究成果如下：1)时间变态造成模型沿程水位、流量过程的滞后，滞后时间和时间变态率及模型长度有关，其大小在涨潮时偏小、落潮时偏大。水位、流量过程曲线在形态上表现为更加扁平，并且天然涨落潮历时分配也被改变，模型中的涨潮历时变长，落潮历时变短。2)含沙量的滞后和偏离作用和时间变态率以及距起始断面的距离有关，含沙量过程曲线变得平缓。挟沙力总体上的变化为涨急时刻偏大，落急时刻偏小。模型总的冲淤量表现为进出口段冲刷量加大，中下游河段淤积量偏大。3)时间变态对分汊河道的影响比单一河道的影响要更大一些，并且对主次河道相对更明显的分汊河道其影响要略小一些。4)时间变态对底床变形的影响依不同河段和地形不同，对模型的河槽、滩地等局部地形的冲淤演变规律有着较为复杂的影响。5)滞后调节下边界水位、增大或者减小进口流量、减缓流量陡涨陡落等手段是本文提出的三个主要的校正措施。更多还原

【Abstract】 The river model test is still the main research method when we make and optimize each kind of hydraulic engineering decision, but the scale effect caused by time distortion in the river model test always can’t be obtained a very good solution. At present the usual procedure is to use the time scale of riverbed scour-aggradation to replace the time scale of fluent-movement in order to obtain the similarity of riverbed scour-and-fill simulation as precise as possible, but this method will cause the deviation of water level, river discharge, send content, as well as the capacity of riverbed scour-and-fill. Particularly in the tidal estuary, its influence is extremely not yet being understood. An unsteady 1-D flow and sediment model is used as a tool in this article to carry three kind of different time distortion rate models on the research of the influence of fluent and sediment movement. And then several preliminary adjusted measures have been proposed. The main research results are as follows:1) The time scale distortion makes the lag of stage and discharge. The lag of time is related to the rate of time scale distortion and the model’s length. Its value is smaller in tidal flood, larger in tidal ebb. The process curve of tidal elevation and discharge displays flatter. And the distributed time of ebb and flow has been changed with the time of rising tide lasting longer and the time of ebbing tide lasting shorter in the distortion model.2) The lag and deviation of sand content is related to the rate of time scale distortion as well as the distance from the outset cross. The sand content’s process curve changes gently. The overall change of silt carrying capacity is that its value is bigger when tide rises anxiously and smaller when tide falls anxiously. The quantity of riverbed scouring enlarges at the import and export section and the quantity of river channel aggradation enlarges at the middle and lower section.3) The influence of time scale distortion on the branch channel is more serious than its influence on the sole river, and its influence is not more serious as to the more obvious branch within two branch channels.4) The influence of time scale distortion on the riverbed deformation is related to the different section of river and the terrain, and it is very complex on the riverbed evolution rule of the river pool or the river shoal and some other partial terrain in the distortion model.5) Lagging adjustment of downstream water level, increasing or reducing the import current capacity, slowing down the sudden-rise or sharp-drop current capacity are the three main methods of adjusted measures proposed in this article.更多还原