糙率变化对明渠水深影响的探讨

Discussions on Influence of Roughness Variation to the Open Channel Flows

糙率对于明渠水力计算有着重要的影响。工程设计中常采用查表法选取渠道糙率,增大了糙率取值的随意性。通过模拟计算与分析,探讨糙率对明渠水深的影响,同时对明渠上下游断面不同糙率的水面衔接问题进行了分析。结果表明:在相同流量情况下,明渠断面越小,糙率对渠道水深的影响越大;在相同流量、相同明渠断面情况下,渠道底坡越小,糙率对渠道水深的影响越大;在明渠断面相同的情况下,流量越大,糙率对渠道水深的影响越大。

The roughness has a significant influence to the hydraulic calculation of the open channel. In engineering design, the look-up table method is often used, but this method increases the arbitrariness in choosing roughness value. Through simulation and analysis, the roughness effect on the depth of open channel was discussed, and the water surface linking problem when the roughness is different between upstream and down- stream section was analyzed also. The results show that：a） Under the conditions of same flow rate, the smaller the section is, the greater influence to the roughness of the channel depth; b） Under the conditions of the same flow rate and section, the smaller the slope is, the greater influence to the roughness of the channel depth; c） Under the conditions of the same section, the larger the flow rate is, the greater influence to the roughness of the channel depth.