石头峡水电站导流泄洪洞研究与设计

Research and design of the diversion flood discharging tunnel of Shitouxia hydropower sation

为了解决因高水头泄水隧洞大流速引起的过流表面冲刷、空蚀造成的"龙抬头"泄水洞混凝土表面冲刷严重等难题,文中以石头峡水电站导流泄洪洞工程为实际案例,对隧洞模型试验成果进行分析总结,优化了渥奇曲线,通过HF混凝土与传统硅粉混凝土对比试验,结合改进施工方法,提高隧洞的抗冲耐磨性能。结果表明:渥奇系数k值越大,水流流态相对较好,工程相对安全,但经济性相对下降,采用x^2=300y渥奇曲线方程,能够有效兼顾工程安全与经济;采用的HF高强耐磨粉煤灰混凝土具有优异的抗冲耐磨强度及施工和易性;采用人工初平,后接机械抹面工艺,保证了无压段3 m靠尺不平整度在5 mm以内,反弧段3 m靠尺不平整度在3 mm以内,达到设计指标和规范要求;经过运行多年后实地观测,反弧末端高流速区最大磨损2 cm,表面光滑完整无开裂破损,说明设计方案合理,达到了预期的目的,有效地解决了高速水流冲刷、空蚀破坏问题,可为以后相关工程设计提供指导和借鉴。

In order to solve the problems such as the serious scour on the concrete surface of the"Longtaitou"spillway tunnel caused by the high velocity of the high head spillway tunnel,this paper takes the diversion and spillway tunnel project of Shitouxia hydropower station as an actual case,analyzes and summarizes the tunnel model test results,optimizes the ogee curve,and through the comparative test of"HF"concrete and traditional silica fume concrete,concludes that combined with the improvement of the construction method to improve the impact and wear resistance of the tunnel.The results show that the larger the ogee coefficient k is,the better the flow pattern is,and the project is relatively safe,but the economy is relatively reduced.The ogee curve equation x^2=300y can effectively take into account the safety and economy of the project;the"HF"high-strength wear-resistant fly ash concrete has excellent impact and wear-resistant strength and construction and workability;the artificial initial leveling,followed by mechanical plastering process,ensures that there is no the unevenness of pressure section 3 m guiding rule is within 5 mm,and the unevenness of counter arc section 3 m guiding rule is within 3 mm,which meets the design index and specification requirements.After years of operation,field observation shows that the maximum wear of high velocity area at the end of counter arc is 2 cm,the surface is smooth and intact without crack and damage,which shows that the design scheme reasonably achieves the expected purpose,effectively solves the problems of high-speed flow erosion and cavitation erosion damage,and can provide guidance and reference for the future related engineering design.