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一、前言 河道中的起动流速是冲刷计算的重要参数,引起国内外很多学者的研究。不同学者从不同假设出发:即动力平衡、泥沙起动流速、以及联系到水流与泥沙特性来研究颗粒起动的随机变化等进行研究,推导出不同的计算公式,在水利、铁道、交通等部门得到广泛应用。但是,这些公式的观测试验资料,最大平均颗粒直径d不超过0.1米,因而对于大颗粒的观测试验,已引起了很多工程技术人员的重视,并迫切需要进行大颗粒起动流速的试验研究。 二、大颗粒起动流速的观测试验 1982年我们在暴雨较多、水量丰沛的峨眉径流实验站上,充分利用现有测流基本断面。在断面上游五米以内排列、平放(没有卡接和埋置)各种不同粒径的砾石并对各种粒径进行编号,如图1和表1所示 当涨洪时,测验各级水位的垂线流速。在此次洪水过后,观察未被冲走的最小粒径的砾石和移动了位置的砾石以及新冲来的砾石,考虑主流位置,砾石移动的状态,反复审视后才
First, the foreword The starting velocity of the river is an important parameter of scouring calculation, causing many scholars at home and abroad to study. Different scholars start from different assumptions: the dynamic balance, the velocity of sediment initiation, and the research on the random variation of particle starting associated with the characteristics of water flow and sediment. Different formulas are deduced. In the fields of water conservancy, railway, transportation and other departments Be widely used. However, the observation and test data of these formulas show that the maximum average particle diameter d is no more than 0.1 m. Therefore, many researchers have paid great attention to the observation of large particles and the experimental study on the flow velocity of large particles is urgently needed. Second, the observation of large particle flow rate test In 1982, we have more rainstorm, abundant water Emei runoff experimental station, make full use of the existing flow measurement of the basic section. Within five meters upstream of the cross-section arrangement, flat (without clamping and embedding) gravel of various particle sizes and numbers of various particle sizes, as shown in Figure 1 and Table 1 When the flood, test all levels Vertical velocity of water level. After the flood, observe the smallest gravel that has not been washed away, the gravel that has moved to the place, and the newly gravel. Considering the mainstream location and the state of gravel movement,