非恒定来流过程对复式河道水动力的影响试验研究

Experimental Study on Influence of Unsteady Inflow Process on Hydrodynamics of Compound Open Channel

非恒定来流过程改变了复式河道水动力特性,进而决定了滩槽的物质传输和能量传递过程。为研究不同非恒定来流过程对复式河道水动力特性的影响,开展室内水槽试验,考虑流量变幅、非恒定周期及涨水历时三个因素,分析不同非恒定来流过程对复式河道水位、水流非恒定性及滩槽单宽流量过程的影响。结果表明,随着流量变幅增加,水位波峰增长斜率大于波谷,波高线性增加,滩槽单宽流量过程均沿时间发生变形,主槽的下降过程和滩地的上升过程存在明显的缓变过程;随着非恒定周期增加,水位波峰增加,波谷降低,波高也呈线性增加,滩槽单宽流量沿时间变形的现象消失;水位波峰波谷与水文偏度同步变化,水文偏度(涨落水历时之比)大于1时,滩槽单宽流量的上升过程也会存在明显的缓变阶段。

The unsteady inflow process changes the hydrodynamic characteristics of the compound open channel and then determines the processes of material transfer and energy transfer in the floodplain and main channel.In order to study the influence of different unsteady inflow processes on the hydrodynamic characteristics of the compound open channel,indoor flume experiments were carried out to analyze the influence of different unsteady inflow processes on the water level,flow instability,and discharge per unit width process of the compound open channel,taking into account three factors:discharge amplitude,unsteady period,and rising duration.The results show that with the increase of discharge amplitude,the slope of wave peak growth of water level is greater than that of wave valley,and the wave height increases linearly.The discharge process of the unit width of the channel is deformed over time,and there is an obvious slow change process in the descending process of the main channel and the rising process of the floodplain.With the increase of the unsteady period,the wave peak of the water level increases,the wave valley decreases,and the wave height also increases linearly.The phenomenon of deformation of the unit width discharge of the channel over time disappears.The water level peaks and valleys change synchronously with the hydrologic skewness.When the hydrologic skewness(ratio of fluctuation water duration) is greater than 1,the rising process of the unit width discharge of the floodplain and main channel will also have an obvious slow change stage.