水库下游卵石河床冲淤演变规律及机理研究

Study on processes of pebble bed along reservoir downstream

通过实测资料和模型试验研究了某水电站下游河道卵石河床冲淤演变规律,探讨了宽级配卵石河床的自动调整作用。在天然条件下,水电站下游河道河床稳定,水库运行后,水流的挟沙能力有很大富余,下游河道发生了较大冲刷。试验表明:在不同流量作用下,河床自上而下以冲刷为主,流量越大,冲刷强度越大;在冲刷过程中,水深变大,流速减小,床沙变粗,河道更加稳定。

The processes of scour and deposition of pebble bed in a reservoir downstream are studied by the observed data and the physical model experiment. The adjustment of the wide graded particles of pebble bed is discussed. Under natural conditions, the riverbed of the reservoir downstream is stable. But the downstream channel was scoured by low sediment concentration flow after the reservoir operation. Physical model experimental results show that the riverbed of downstream of reservoir was mainly occurred along the river with water releasing. The larger the release flow, the more intensity of scour. During scour the water depth increase gradually, the flow velocity was slower, the bedload became coarser and the river bed is more stable.