Research On Design,construction And Stability Of Bowl-buckle Formwork Support System

Due to its advantages of large bearing capacity,simple fabrication and reasonable structure,bowl-buckle formwork support system has been widely used in subway tunnel construction.However,there are some problems,such as rough design and checking,unreasonable construction measures,resulting in the collapse of the formwork support system accidents.Therefore,engineers need to pay special attention to the design,construction and stability research of formwork support system.This paper takes a subway station project of a city as the engineering background,and the formwork support system used to support the internal main structure is designed and checked.On this basis,a finite element analysis model is established,and the linear buckling analysis and nonlinear buckling analysis are carried out respectively,and then the ultimate bearing capacity of the formwork support system is studied.Finally,the construction organization design is given to ensure the safety of the formwork support system during the construction process,so as to reduce the collapse of the formwork support system.The main research contents and conclusions are as follows:(1)Taking a subway station project of a city as the background,bowl-buckle formwork support system used in the main structure of the support is designed and checked to ensure that the design scheme meets the requirements of the specification.(2)The finite element analysis model of bowl-buckle formwork support system considering semi-rigid joint connection is established by MIDAS/GEN finite element software.The linear and nonlinear buckling analysis are carried out respectively.It shows that the results of the nonlinear buckling analysis results are more consistent with the actual engineering situation than those of the linear buckling analysis.(3)The control variable method is used to study the ultimate bearing capacity of bowl-buckle formwork support system,and the effects of different factors on the stability of bowl-buckle formwork support system are analyzed.The results show that the ultimate bearing capacity of the formwork support system decreases with the increase of the height of the bottom horizontal tube;when the height of the bottom horizontal tube is less than0.4m,the ultimate bearing capacity of the formwork support system decreases little;when the height of the bottom horizontal tube is more than 0.4m,the ultimate bearing capacity of the formwork support system decreases significantly.The ultimate bearing capacity of the formwork support system decreases with the increase of the length of the standing tube beyond the top horizontal tube;when the length of the standing tube beyond the top horizontal tube is less than 0.5m,the ultimate bearing capacity of the formwork support system decreases little;when the length of the standing tube beyond the top horizontal tube is more than 0.5m,the ultimate bearing capacity of the formwork support system decreases significantly.The horizontal brace has no significant effect on improving the ultimate bearing capacity of the formwork support system than the vertical brace,but it can effectively reduce the transverse deformation of the formwork support system.With the increase of the erection height,the ultimate bearing capacity of the formwork support system gradually decreases,but the decreasing tend is gradually flat.The ultimate bearing capacity of the formwork support system decreases with the decrease of the steel tube wall thickness.The smaller the steel tube wall thickness is,the greater the reduction of ultimate bearing capacity of the formwork support system is.(4)This paper presents the construction organization design of bowl-buckle formwork support system,including construction deployment,construction method and construction assurance measures,in order to ensure the installation quality and the installation safety of the formwork support system in the process of installation.