| In recent years, high-performance concrete is commonly used in the construction of cantilever box girder bridge, its excellent workability and mechanical fully meet the needs of structure and construction to cast cantilever box girder bridge in present, but at the same time, it also leds large numbers of construction cracks to box girder. In view of this situation, the paper combines high performance concrete material properties and the present stutation of cast cantilever construction, analysis on the causes of the construction cracks to cast box girder bridge deeply, propose appropriate disposal methods comprehensly, namely the controling of concrete performance during constructing, and the early pouring after the completion of concrete.This article comes from the western transportation construction projects "Influence and Countermeasure of Fineness and Components of Cement on Properties of Concrete in Bridge Engineering(2009318000033)" and Chongqing Jiaotong projects " Curing method to large span prestressed concrete continuous rigid concrete box girder in cast-in-place cantilever construction method", Relying on Ganshui bridge, led by theoretical analysis and field practice as, to carry out the following work:①According to the current situation, analyze the impact of the various components of the early performance of high performance concrete pouring concrete with the boom,summarized the early performance characteristics of high performance concrete.② Summary cantilever construction of box girders of crack distribution and characteristics, analyzes the construction of the main causes of the cracks. And the quality of raw materials selection, box girder box beam construction demolition timing and other aspects of the early conservation, make recommendations on the construction of crack control.③ Detailed analysis of common principles and concrete stage adaptive maintenance method combines cantilever pouring box beam construction technology,high-performance concrete and concrete box girder early performance of early changes of temperature, the adaptability of the method of evaluation of the conservation and comprehensive results Pouring concrete cantilever most appropriate conservationmethods, namely molding paste + artificial + automatic spray composite curing methods.④ According to the status cantilever placement and construction methods,combined with high performance concrete Early shrinkage performance characteristics,analyzes the construction process, the removal time for cracking of the concrete surface,and temperature variation through the early box girder finite element simulation, and then make appropriate removal time limit.⑤ Relying catch water bridge on concrete material selection, optimization, and analog stick Mix + labor + automatic spray composite curing methods and application specific steps to evaluate the effect, thus forming a complete set of box girders cantilever construction method of crack control. |
