考虑温度荷载作用的白鹤滩隧洞衬砌拆模时间研究

Study on removal time of lining formwork of Baihetan Tunnel under the action of temperature load

大型隧洞衬砌拆模时间对于工程施工进度、工程造价和工程质量都有重要影响。实际工程施工过程中,根据顶拱衬砌结构特点,考虑混凝土强度增长及施工质量控制要求,衬砌拆模时间一般为12~36 h,与有关混凝土施工规范的时间要求有差距。以白鹤滩泄洪洞上平段衬砌为研究对象,根据混凝土早期温度应力变化特点,提出隧洞顶拱衬砌拆模时间需综合考虑混凝土强度增长及温度应力的共同作用,以拆模时间24 h为宜,并需在拆模后加强衬砌混凝土的保湿养护。

The formwork removal time of large tunnel lining project has an important influence on the construction progress,project cost and project quality.In the actual construction process,considering the characteristics of the top arch lining structure,the increase of concrete strength and the requirements of construction quality control,the time of lining formwork removal is generally 12-36 h,which is different from the time required by the relevant concrete construction specifications.In this paper,the lining of the upper flat section of the Baihetan spillway tunnel is taken as the research object.According to the characteristics of early temperature stress variation,this paper puts forward that the removal time of the tunnel top arch lining needs to consider the joint action of concrete strength growth and temperature stress comprehensively,24 hours should be taken as the appropriate time,and the moisture conservation of lining concrete should be strengthened after removal of formwork.