Construction Of Large Diameter Earth Pressure Balance Shield And Analysis Of Cutter

In recent years,with the accelerated process of urbanization in China,urban traffic pressure is increasing,therefore,the underground space has been developed.As a safe and efficient tunnel construction method,shield tunneling method has been widely used in urban subway,underground pipeline and other tunnel projects.The earth pressure balance shield machine has its technical and economic superiority,occupying an absolute dominant position in the shield construction method,and achieves dominance in the city underground engineering construction technology.The main contents of this paper include the following aspects:1)Relying on the actual project background,and the research background and purpose of large-diameter EPB shield machine for composite formation construction are put forward.The structure,function and tool layout of large diameter cutter are studied.2)Participating in the construction practice of the project,focusing on the launching of the shield machine,solutions are carried out to the complex and difficult problems such as originating,linear control,spewing,mud cake,mixed ground and midway replacement.3)Studies are done on the stress analysis and calculation of the cutterhead under various complicated working conditions during the actual construction.According to the actual construction situation,the stress analysis of the load case of the project is completed in detail.The stress of all kinds of dangerous load cases is calculated,providing the numerical basis for the following mechanical analysis and optimization of the cutterhead.4)Combining the structural characteristics of the cutterhead of the shield machine and the construction conditions of the construction site,the mathematical model is established by several construction conditions and the digital mechanics analysis of the cutterhead structure is made from the theoretical height.The safety analysis results of the dimensions of the cutterhead are obtained.5)In the case of lm block of soft soil,the cutterhead is optimized by finite element method,and the simulation results in an optimized size of the structure,which makes the stress of the shield point smaller and the structure size more reasonable,and provides a reference to the design and optimization of the cutter.The research results of this paper show that the cutterhead of a shield machine used in 6th section of Dongguan-Hui intercity railway is reasonable in force,which can meet the requirements of construction in safety and quality.At the same time,through the analysis of the force of the cutterhead in the most complicated condition,it is found that the cutterhead structure can be optimized and a more reasonable structure dimension can be put forward,which makes the cutterhead structure safer and more reasonable.The results of this paper can be a reference for the design of cutterhead structure,and also have some reference value for tunnel shield construction.