一、综合延伸法的理论基础 在动床模型试验中,由于模型沙的运动状态很难与原型沙完全相似,因而试验的结果常有一定的偏差。显然,当模型沙就用原型沙时,试验结果的偏差程度,必然与模型的大小有一定的联系,模型越大,偏差就愈小,模型大到和原型一样,偏差就等于零。因此,从这一基本概念出发,就可同时作一系列大小不同的模型,将各模型得出的试验结果,点绘在双对数纸上,顺其势延伸到原型,从而得出没有偏离的原型值,这种方法叫做系列模型延伸法。但有时系列模型延伸法无法满足要求,例如当原型沙过粗,用这种沙做冲刷试验,模型中的水流无法冲动,因而系列模型延伸法无法满足要求。为此,我们从下面的概念出发,得出系列沙粒延伸法。假如我们的模型就是原型,模型沙不是原型沙,而是适合试验的某种天然 First, the theoretical basis of the comprehensive extension method In the moving bed model test, because the movement of the model sand is difficult to be completely similar to the prototype sand, the test results often have a certain degree of deviation. Obviously, when the model sand uses prototype sand, the degree of deviation of the test results must have a certain relationship with the size of the model. The larger the model, the smaller the deviation. The model is as large as the prototype, and the deviation is equal to zero. Therefore, starting from this basic concept, a series of models of different sizes can be made at the same time. The experimental results obtained by each model can be plotted on double logarithmic papers and extended along the way to the prototype, so that no deviation is found. The prototype value, this method is called the series model extension method. However, the series model extension method sometimes fails to meet the requirements. For example, when the prototype sand is too coarse, the sand model is used for flushing test. The flow in the model cannot be impulsive, so the serial model extension method cannot meet the requirement. To this end, we proceed from the following concepts and draw a series of sand grain extension methods. If our model is a prototype, model sand is not a prototype sand, but a natural one suitable for testing.