| With the rapid development of urban rail transit,the construction of tunnel projects under buildings(structures)has become increasingly numerous,and the pipe curtain structure has been widely used as an advanced support structure.SSCP(Steel Support Cutting Pipe Method)pipe curtain structure is a shallow buried.large-span pipe curtain support system,with large diameter steel pipes are pushed into the soil on the top and sides to form an inverted "U"shaped support frame structure.Then cut the groove along the transverse direction of the steel pipe at a certain distance,and weld the steel plates at the steel pipe slotting position to connect the adjacent steel pipes together.As the soil under the pipe curtain is excavated,the steel support is erected at the slot and welded with the connecting steel plate to form a structure similar to a portal steel frame.The SSCP pipe curtain structure all uses steel structure as a supporting force system.For the design of steel structures,it is necessary to meet the requirements of stability and deformation.In this paper,the theoretical analysis and numerical simulation methods are used to systematically study the structural stability ultimate bearing capacity and deformation characteristics of the SSCP pipe curtain structure,it is intended to provide a reference for the promotion of this structure,the specific contents are as follows:Through the combination of theoretical calculation and numerical simulation to study the stability ultimate bearing capacity of the SSCP pipe curtain structure,and the calculation formula of the elastic stability ultimate bearing capacity of the SSCP pipe curtain structure is proposed,and the influence of the parameters such as the wall thickness of the steel pipe,the thickness of the connecting steel plate,the height of the steel support frame,the cross-sectional size of the steel support frame on the stability ultimate bearing capacity are analyzed.The results of the study show that the height of the steel support frame and the size of the steel support section have a significant effect on the structural stability ultimate bearing capacity,while the wall thickness of the steel tube and the thickness of the connecting steel plate have an effect on it,but the degree of impact is less.Through the method of numerical simulation,the deformation characteristics of SSCP pipe curtain structure and the law of surface settlement are analyzed,and the parameters of the structure are explored.The results show that the increase in the longitudinal spacing of the steel support,the cross-sectional size of the horizontal steel support,and the size of the vertical steel support section have a significant effect on the vertical deformation of the steel support and the surface settlement displacement of the tunnel;The increase in the size of the diagonal steel support section has little effect on directional deformation and surface settlement displacement of the tunnel.Through the method of combining multi-index orthogonal experiment and fuzzy mathematics to optimize and analyze the parameters of SSCP pipe curtain structure.The results of the range analysis of the orthogonal test show that among the many parameters,the greatest influence on the deformation of the SSCP pipe curtain structure is the longitudinal spacing of the steel support,followed by the transverse steel support section size,and the smallest impact is the diagonal steel support section size.The optimal evaluation index of steel support parameters is determined by fuzzy mathematics theory,the analysis shows that when the tunnel is buried 5 meters deep and there are no buildings(structures)in the upper part,the optimal parameter combination of the steel support of the SSCP pipe curtain structure is the steel support longitudinal spacing of 1.5 m,the horizontal steel support section size is HW300×300,the diagonal steel support section size is HW175×175,and the vertical steel support section size is HW300×300. |
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