复式河槽阻力系数及过流能力计算

Computation of resistance coefficient and conveyance capacity in compound channels

水位流量关系在流域管理中占有十分重要的地位。而对于复式河槽,水位流量关系的推求是十分困难的。无论采用单一河槽法还是传统的断面分割法,都将带来很大的误差。将复式河槽分为滩地边坡区、滩地区、主槽边坡区和主槽区,并运用英国科学工程研究协会洪水水槽设施(SERC FCF)的大量的系列水槽实验资料,分析了各区Dar cy Weisbach阻力系数之间的关系。SERC FCF的实验资料表明主槽区的阻力系数与相对水深有关,滩地区和主槽区阻力系数之比随相对水深成指数关系,滩地边坡区、主槽边坡区阻力系数可用主槽区和滩地区阻力系数表示。利用这些阻力系数关系分别推求各区的流量及总流量。实验资料验证表明:计算流量与实测流量基本吻合。

Stage-discharge curves are particularly important in river basin management. For compound channel, it is difficult to produce the stage-discharge curve. In computing conveyance capacity, adopting either the single channel method or the conventional divided cross section method will result in enormous error. In this paper, a compound channel is divided into four sub-regions: the flood-plain-side-slope region, the flood-plain region, the main-channel-side-slope region and the main-channel region. By analyzing a large numbers of experimental data from the Science and Engineering Research Council Flood Channel Facility (SERC-FCF), the Darcy-Weisbach resistance coefficient relationships among them are established. The experimental data from SERC-FCF show that the resistance coefficient in main-channel region is related to the relative depth (Dr), the ratio between the resistance coefficient in flood-plain region and that in main-channel region varies exponentially with Dr, and the resistance coefficients in flood-plain-side-slope region and the main-channel-side-slope region can be expressed by those of the flood-plain region and the main-channel region. Finally, by computing the discharge in every sub region on the basis of the resistance coefficient relationships, the total discharge can be obtained. The experimental data show that the computed discharge is in close agreement with the measured one.