Research On Key Technology Of Cast-in-place Box Girder Support In Wushui Section Of Chongqing Subway

The cast-in-place box girder has the advantages of large rigidity,good appearance,overall performance,good seismic performance,and the like,and is widely used in modern bridge construction.The cast-in-place box girder is used in urban elevated structures to meet the requirements of municipal engineering aesthetics.As a construction platform for box girder,the bracket structure is widely used in cast-in-place box girder engineering and is a relatively mature,simple and economical construction method.At present,during the construction of cast-in-place box girder brackets,the collapse of the brackets frequently occurs,causing huge personnel and economic losses.It is an urgent task to study and improve the stability and safety of the bracket structure.This paper relies on the cast-in-place box girder support project of the elevated section of the Wulidian Station-Jiyuxi Station in the first phase of the Chongqing Rail Transit Line 9 project,focusing on the coiled steel pipe bracket and the steel pipe column+Bailey beam bracket.Stability of the two stent structures.The Wuzhi interval elevated section QJ 15-D01～QJ15-D02#-40m simply supported beam is equipped with a scaffolding scaffolding as a support structure for concrete pouring(QJ15-D02～QJ15-D05/QJ15-D08～CZ 16-D01#The cast-in-place box girder adopts the steel pipe column+Berea beam bracket system as the support system for concrete pouring.The topography of this project is complex,the overlying soil layer is thicker,and the support is difficult to detach and the quality requirements are high.This paper combines engineering cases,based on the existing support system engineering background,using theoretical calculations,numerical simulations and field measurements.The study studies the stability and safety of the box girder structure.The main research contents are as follows:(1)According to the complex environmental conditions on site,reasonably arrange the structure of the bracket and select the appropriate basic form to ensure the uniformity and stability of the structure and foundation of the bracket.(2)After the bracket is erected,the strength,rigidity,integrity and safety of the bracket structure are checked,and the pre-pressure test is carried out in sub-regions.(3)Calculate and analyze the structure of the stent to ensure the mechanical properties of the stent structure.The disc-type bracket adopts the theoretical calculation method,and the steel pipe column-Beyley beam bracket adopts the method of numerical simulation analysis.(4)During the pouring process of the box girder and after the pouring is completed,the bracket structure and the bracket foundation are monitored and measured,and whether the settlement amount and the horizontal displacement during the observation period are within the allowable range of the design specification.Figure[84]Table[12]Reference[54]...