弧形结构清水混凝土现浇箱梁施工技术

The construction technology of cast-in-place arc-shaped fair-faced concrete box girder

对于弧形箱梁清水混凝土结构,在实际应用过程中出现了一些问题,例如施工模板不适用、模板钢筋安装效率低、外观质量难达标等。本文以某市政桥梁工程人行梯道施工为例,系统介绍了变曲率、变高度、变宽度弧形箱梁整套施工工艺。通过与偏角法、极坐标测量法对比研究,总结出更适用于弧形箱梁施工的道路中线推进测量放样技术。对比国内常用模板材料的密度、配备情况、加工安装质量及难易程度,力学性能等,包括定型钢模板、玻璃钢模板、充气内模、铝合金模板、双壁波纹管、塑料模板等。比选出菲林板+不锈钢复合模板作为弧形箱梁侧模板,双壁波纹管作为内模材料。施工前,针对箱梁配筋情况,结合BIM模型,综合分析,提前部署,确定钢筋安装、混凝土浇筑顺序。过程中进行质量安全控制、形成弧形箱梁钢筋安装及混凝土施工工艺。

Some problems have arisen in the practical application process for the arc-shaped box girder fair-faced concrete structure,such as unsuitable construction formwork,low efficiency of steel bars installation for the formwork,and the difficulty of meeting the appearance quality standards.In this paper,the construction of pedestrian stairway of a municipal bridge project was taken as an example,which systematically introduced the whole set of construction techniques of arc-shaped box girder with variable curvature,height,and width.An applicable survey lofting technique for the advancement of road centerline for the arc-shaped box girder construction was obtained by comparing with deflection angle method and polar coordinate measurement method.The density,equipping situation,processing and installation quality and difficulty,mechanical properties,etc.of commonly used domestic formwork materials were compared,including fixed steel formwork,FRP formwork,inflatable inner mold,aluminum alloy formwork,double-wall corrugated tube,plastic formwork,etc.The composite formwork formed by the laminate combined with stainless steel and the double-wall corrugated tube were selected as the side and the inner formwork of the arc-shaped box girder,respectively.Before construction,the sequence of reinforcement installation and concrete pouring was determined in advance by using BIM model comprehensive analysis according to reinforcement distribution of the box girder.Quality and safety were controlled during the construction process to form the steel installation and concrete construction techniques of the arc-shaped box girder.