薄壁混凝土槽型梁裂缝控制技术研究

Crack Control Technology of Thin-wall Concrete Channel Girder

槽型梁多为薄壁混凝土,底板内布置双向预应力筋以增强其整体刚度及抗裂性能,由此对施工工艺提出了较高的要求。新建京沈铁路客运专线采用薄壁混凝土槽型梁结构,为国内工程中首例应用,由于安全等级较高、使用寿命较长,施工时应制定合理工艺及工序以满足其抗裂要求。本文从模板布置、钢筋绑扎、混凝土浇筑及养护三个方面控制裂缝的产生,具体阐述施工工艺及实现过程,针对槽型梁结构特点制定双向预应力张拉工序,并采用MIDAS/Civil软件对张拉过程中槽型梁应力分布进行计算,以保证张拉工序合理、可靠,为类似工程提供经验。

Channel girder is properly made of thin-wall concrete members, in practice. And horizontal and longitudinal prestressing tendons are always put into the bottom plate, in order to improve the integral rigidity and crack resistance. Beijing-Shenyang Passenger Dedicated Line is the first application of channel girder with higher safety class longer service life, causing more strict crack resistance in construction. Measures of controlling crack is provided during manufacturing frameworks, assembling reinforcement, and placing and curing concrete. Bidirectional prestressing process is presented when considering the structural features. The verification of prestressing is executed by the stress distribution, with the help of MIDAS/Civil. The procedure and technology of controlling crack can be applied to similar projects.