Test Study On The Upstream Partof Side Channel Spillway And Stepped Spillway Of The First Step Hydropower Stationin In Gang-Qu River

As one of more important and familiar discharge structure in hydraulic structure, the hydraulic characteristics of spillway has been enjoying the concern of hydraulic engineering field, they have done a great deal of experiment research and acquired a great deal of results.The first step hydropower station in Gang-qu river located on the first order affluent of Jinsha-River's upper stream named Gang-qu river in Di-qing Tibetan autonomous prefecture of Yunnan province , the dam is reinforced concrete face rockfill dam, considered of fill dam stone, rock-fill dam and light dam generally disallow to overflow flow from the dam body or discharge a great deal of flow, according to the terrain and geology condition, the scale and economy of engineering, chose side channel spillway to overflow and release excessive water. Owing to the key technique problems of the side channel spillway are the upper stream parts of the spillway, downstream parts belong to a conventional technology problem, all have already involved in all spillways, this paper collects the energy to resolve the key problem of side channel spillway. This paper based on the original design project, through many times modification and optimization, setting abrupt slot segment at the end of side channel and 2m height weir at the end of abrupt slot segment, can significantly lower surface line of bend segment, average lower 4.5m, biggest lower 5.76m, can save the excavated volume; Through setting baffle block in side channel , can eliminate transverse rotating flow in the side channel, and improve the flow pattern obviously, make the water surface more smoothly, the max value of difference percentage of maximal and minimal depth of water declined from 42.10% to 13.44% in side channel, but the flow of bend segment is deterioration in the meantime.At the same time, the good energy dissipation characteristic of stepped spillway caused extensive concern of engineering field, but building spillway on the face rock-fill dam is rarer, so this paper has also studied on the hydraulic characteristics of stepped spillway. The text shows that , in the eyes of the hydraulics, setting at 60cm height, 96cm width steps is feasible, stepped spillway has high energy dissipation ratio, there is no scouring and silting in the down-stream, but needs to argue the feasibility from structure.This paper use the opinion of Nikuradse, Cai-Keshida etc,. treats steps as roughness problem, so according the test result of them to acquire the water surface formula, which is apt to the test data. But totally to say, this formula needs to be based on a great deal of experiment data, this paper limits test data, the applicability and validity of which need to be further tested and improved.