The Design Research Of EPB Shield Cutterhead Based On Gravel Strata

Due to having higher safety and reliability in the process of construction, Earth Pressure Balance(EPB) shield machine is used in the construction of tunnel and subway widely. Sand and gravel stratum is one of many complex strata, which has a wide distribution and representation in our country. In this thesis, cutter head design on Gravel Strata is regarded as the research object. The design criterion of cutter head, cutter selection and arrangement, and the load distribution of the shield are studied in this thesis. The main research contents are as follow:Firstly, characteristics of gravel strata is analyzed, main points of the cutter head designing are put forward according to the engineering case of the gravel stratum construction.Secondly, based on the analysis of functions and failures modes, the base rules of cutter head designing are established, and the strength and stiffness calculation formulas are founded.Analyzing come to the conclusion that the max-stress point appears when stand bar and Bearing flange meet each other, and which provides theoretical basis for performance evaluation of the shield cutter head.Then, the principle of the cutting tool selection is given based on the cutting tools functions and characteristics. Secondly, the calculation method of the cutter arrangement on cutter head is established based on analysis model of the cutter and hob. Thirdly, the cutter head force and tool life are regarded as the study objects, the cutter layout method is analyzed based on cutter head force balance and uniform cutting tool by the cutter arrangement method of Archimedes spiral line. Finally, the rationality of the cutter layout method is verified through combining engineering examples.After that, calculation models for thrust and torque of the cutter head are established through analyzing the constituent elements of thrust and torque in the condition of sand and gravel stratum. The algorithm for the frictional resistance of shield shell and stratum is obtained according to related geological parameters. Comparing with the previous one, the new calculation method is more accurate and effective with avoiding the waste of material.Finally, the performance evaluation of the cutter head in aspects of strength and stiffness is finished based on the shield construction case of Shenyang. Then, the 3-D simplified model of the cutter head is established in Pro-E, and the finite element analysis is implemented by ANSYS based on actual working condition. The rationality of the cutter head structure and design standard in the condition of sandy pebble stratum is verified.