大石峡水利枢纽工程导流洞进口渐变段混凝土衬砌施工技术

Construction Technology of Concrete Lining at the Transition Section of the Diversion Tunnel Inlet of Dashixia Water Control Project

大石峡水利枢纽导流洞进口渐变段由于跨度大、衬砌厚,且进水塔已经浇筑完成后上下游端形成封闭,混凝土衬砌和洞顶饱满度和密实度质量保证难度大。经论证分析采用满堂脚手架支撑,将拱顶混凝土分层浇筑,进口端预留进人竖井通道、后期一次封堵的混凝土施工方案;并通过有限元计算分析顶拱的变形应力,顶拱第一层(厚度大于1.5 m)强度达到50%时即可浇筑上一层。施工方案保证了拱顶浇筑密实且与洞壁紧密接触脱空小,避免顺洞壁渗漏,确保了渐变段的工程质量和进度,有一定参考价值。

Due to the large span and thick lining of the transition section at the inlet of Dashixia diversion tunnel,and the sealing of the upstream and downstream was formed after the completion of the concreting of the water intake tower,it was difficult to ensure the quality of the concrete lining and the fullness and compactness of the tunnel roof.After the demonstration and analysis,the full scaffold support was adopted to cast the concrete at the arch top in layers,and the concrete construction scheme of one-time sealing at the later stage was reserved at the entrance of the access shaft;And through the finite element calculation and analysis of the deformation stress of the crown,when the strength of the first layer of the crown reaches 50%,the next layer can be poured.The construction scheme ensures that the arch crown was poured densely and closely contacted with the tunnel wall,avoiding leakage along the tunnel wall,and ensuring the engineering quality and progress of the transition section,which is of reference value to similar projects.