堰塞湖溃决过程人工干预试验研究

Experimental Study on Manual Intervention Upon Barrier Lake Failure

针对堰塞湖溃决洪峰过大、堰塞体坍塌过程难以控制等工程难题,通过野外模型试验对比研究不同横、纵断面结构形式引流槽溃决洪水特点,并开展石笼串及柔性网等柔性防护措施控溃削峰技术研究,实现人工干预调控堰塞湖溃决过程。试验结果表明,相比于梯形断面引流槽,复式断面引流槽能明显降低堰塞体过水高程、提升溃决初始阶段过水效率、降低堰塞湖溃决洪峰;垂直陡坎能局部增大溃决水流流速,加速溯源陡坎回溯冲刷,进一步提升溃决初始阶段过流效率、加速堰塞体坍塌,造成溃决洪峰稍稍增大,但库区最大雍高水位有所降低;石笼串及柔性网分别通过延缓溃决水流横向展宽及纵向下切掏蚀堰塞体,减缓溃决水流过流宽度及水头变化,延迟堰塞体坍塌溃决,延长溃决洪水历时曲线,降低堰塞湖溃决洪峰,溃决洪峰最大可削减20.2%。

Aiming at the engineering problems of large outburst flood peak and uncontrollable outburst process in the emergency disposal of barrier lakes, this paper proposes to adjust the spillway structure(compound section and vertical scarp) and then investigates the influence of softly protective measures(gabion strings and soft nets) upon the barrier lake outburst process on a basis of field model test. Compared to the hysteretic outburst process of the conventional trapezoidal spillway, the compound spillway would significantly reduce down the overtopping elevation to improve the initial discharge efficiency and then correspondingly decrease down the outburst flood peak. But the vertical scarp in the downstream region of spillway would excessively speed up the retrospective scour development and slightly accelerate the barrier body failure, thus resulting into higher outburst flood peak but lower reservoir water level. The gabion strings and soft nets would respectively alleviate the lateral widen and longitudinal down cut by the outburst flood, which could significantly delay the barrier body failure and flatten the outburst flood curve with outburst flood peak to be 20.2% down. Most importantly, such softly protective measures can self-adjust their own structures to adapt to the spillway deformation with the development of barrier body failure and can provide a well reference for manual intervention in the emergency disposal of barrier lakes.