【摘要】 不均匀级配的卵石河床的推移质输沙率是生产中的一个重要课题.由于测验困难,许多河流尚无系统的原型观测资料.用一般的公式计算,结果相差较大.从1965年以来,为满足水电站工程设计需要,我们曾多次采用水槽模拟试验方法,以推求卵石河床的推移质输沙率,积累了一些经验. 水槽的床沙及水流条件均按模型相似率设计.试验时根据水槽出口的输沙测验值,调整进口的加沙量和级配,直到进出口的输沙率及级配相近,作为平衡输沙的控制条件.用水槽试验结果推算天然时,考虑了水槽侧壁的影响.当床沙中的细颗粒难以完全满足相似条件时,可用试验资料检验和修正输沙率公式,再用公式计算天然.更多还原

【Abstract】 Bed load transport rate is an important problem in the development of rivers of gravel bed. Due to the difficulties in field measurement, there is still lack of systematic data in many rivers. As for the existing bed load formulae, they usually give results at variance with one another. Hence, in this paper, a method by using flume experiment as model to give a basic bed load transport function per unit width of the river is proposed. And, by converting this function to the whole cross-section of the prototype, the total bed load transport rate is obtained.The flow conditions and the composition of the bed material corresponding to a typical reach of the river being studied were modeled in the flume according to a certain criteria of similarity. Based on the bed load samples collected at the downstream end of the flume, the bed load had been recirculatively fed back at a certain rate into the upstream end of the flume until an equilibrium state was achieved, whereas the composition of the bed material remained constant during the whole test.In the process of establishing the bed load transport function per unit width of the model, the effect of the wall-side roughness should be separated. If the similarity of the composition of the bed material can be perfectly simulated, the bed load function per unit width of the model could be directly converted to the whole cross-section of the prototype. If there is somewhat deviation from similarity due to the difficulties of the maunfacture of model sand, it is necessary to verify and modify some existing bed load formulae with the experimental data and then to calculate the bed load transport rate of protoype by using the modified formula.更多还原