金沙水电站导流明渠截流施工技术研究

Study on construction technology of open diversion channel closure in Jinsha Hydropower Station

金沙水电站导流明渠截流面临着流量大、龙口流速快、落差大,明渠岸坡陡峭、渠底平整光滑以致抛投料难以稳定堆积以及截流施工难度大、施工效率低等问题。通过开展截流物理模型试验,合理确定了水力学参数,并优化了截流物料和戗堤布置,以降低导流明渠截流流速。根据现场情况和模型试验结果,提出在明渠底板预埋工字钢、明渠侧墙预埋锚钩,并且在靠近纵向围堰混凝土光滑面一侧先行施工墩头戗堤等技术措施,以增加导流明渠过流断面摩擦阻力,提高抛投料堆积的稳定性。同时,在靠近纵向围堰处设一拦沙坎缺口以改善分流条件,并且控制下泄流量、采取防止堤头塌滑等技术措施,降低截流施工难度,提高截流施工效率。上述措施在工程实施中得到了成功应用,确保了导流明渠截流的实施。研究成果可为同类工程提供一定参考。

The closure of open diversion channel of Jinsha Hydropower Station is faced with the problems of large flow rate, high flow rate at the gap, large drop, steep bank slope of the open channel, smooth bottom of the channel, which makes it difficult to stabilize the accumulation of throwing materials, difficult closure construction and low construction efficiency.Through the physical model test of closure, the hydraulic parameters were reasonably determined, the closure materials and dike layout were optimized to reduce the closure velocity in the open diversion channel.According to the field situation and model test results, it was proposed to in advance imbedded I-steel in the bottom of the open channel, anchor hook in the side wall of the open channel, and to in advance construct pier head dike near the smooth side of longitudinal cofferdam concrete, so as to increase the friction resistance of the flow section and improve the stability of projecting material.At the same time, a barrier gap near the longitudinal cofferdam was constructed to improve the diversion conditions, and technical measures such as controlling discharge and adopting embankment head collapse were taken to reduce difficulty and improve efficiency of closure construction.The successful application of the above measures in the engineering implementation ensured the implementation of open diversion channel closure, which can provide some reference for similar projects.