70 m PC整孔预制箱梁施工关键技术分析

以主通道项目非通航孔桥70 m PC箱梁为背景,利用BIM技术对预制场布局合理划分,优化海工混凝土配合比,采用钢筋模块化生产、内模滑移式设计、自动喷淋养护技术等方式极大提高了箱梁预制工效。深入分析大跨度PC箱梁预拱度设置,建立了边、中跨的预拱度函数曲线,指导了箱梁预制施工。自主研发1 200 t通用门式起重机,可适应场地大纵坡的不利影响,提升箱梁场内搬运效率。借助信息化手段对箱梁海上运输实时监控,保障了海上运输的安全。箱梁海上安装的关键在于吊具,设计了一种自重轻、结构简单的下托梁杆结构。通过ANSYS进行最不利受力分析,验证了吊具受力合理、强度、刚度及稳定性均满足要求。

Key Technology Analysis of 70 Meters PC Whole Hole Precast Box Girder Construction

Taking 70 meters PC box girder of non-navigable hole bridge of the main channel project as the background, the prefabrication site layout is reasonably divided by using BIM technology, the mixing ratio of Marine concrete is optimized, and the prefabrication efficiency of box girder is greatly improved by means of modular production of reinforcement, sliding design of internal mold and automatic spray curing technology. Based on the analysis of the pre camber setting of long-span PC box girder, the pre camber function curve of side and middle span is established, which guides the construction of box girder prefabrication. Self developed 1 200 t universal gantry crane can adapt to the adverse effects of large longitudinal slope of the site and improve the efficiency of handling in the box girder field. With the help of information technology, the real-time monitoring of box girder maritime transportation ensures the safety of maritime transportation. The key to the offshore installation of box girder lies in the spreader. A lower joist structure with light weight and simple structure is designed. Through the most unfavorable stress analysis of ANSYS, it is verified that the spreader is reasonable in stress, strength, stiffness and stability meet the requirements.