滩坑水电站过水围堰堰型修改模型试验研究

Experimental study on modification of the overtopped cofferdams for the Tankeng hydropower station

滩坑水电站工程采用全段围堰和隧洞泄流的导流方式。上下游围堰均采用土石过水围堰型式。通过初步模型试验,调整了堰体和坝体过流保护措施。为进一步改善上游过水围堰的水力条件,降低过堰最大流速,确保围堰和坝体度汛安全,进行了堰型修改模型试验。本文试验中,进一步研究了降低上游围堰高程、抬高上游围堰下游侧平台高程、抬高大坝过流坝面高程和下游围堰坝顶高程的各种组合工况的技术合理性。这些成果为工程导截流设计与施工组织及坝体度汛提供了重要的指导作用。

At its diversion stage the Tankeng hydropower station adopts tunnel diversion and two earth-core rock cofferdams of overtopped type located upstream and downstream the dam site.A preliminary scale-model test was conducted to study the protection measures against overtopping of the cofferdams and the dam.Through this test the shape of upstream cofferdam was modified to further understand the hydraulic conditions and to reduce the maximum flow velocity,which is important to the safety of the cofferdams and the dam during flood season.This paper presents a discussion on the technical feasibility of various combinations of engineering measures,such as lowering the crest of the upstream cofferdam,raising the platform of the cofferdam,raising the dam elevation,and raising the crest of the downstream cofferdam.The results provide a useful guide for the design of diversion and closure,construction planning and flood protection at dam construction stage.