Research On The Sealing And Transportation Characteristics Of Screw Conveyor In EPBS

Earth pressure balance shield machine (EPBS), which evolved from compressed air shield machine and the Slurry Shield, is most widely used at present for its wide applicability and the less pollution. With a whole section cutting-plate in the front end, a sealed cabin is formed to deposit the soil, at the bottom of which a screw conveyor is equipped. The soil and the mud cut down fills the cabin to balance the press of the excavation face, so that the disturbance of the soil and the sedimentation of earth is lowed down.The structure of screw conveyor in EPBS is similar to the ordinary. But the working conditions are very different. First of all, the scew conveyor in EPBS is in a state of back-pressure transmission, for the high pressure in the cabin, whereas the pressure in ordinary one is Atmospheric pressure. Secondly, the screw conveyor is a pivotal pressure control unit in EPBS. It is full of soil, which forms a embolism to transport sealed. While the filling rate in the ordinary screw conveyor is about 1/3～1/2, so to not be blocked. Finally, accurate transportation is needed in EPBS to control the pressure of the sealed cabin.It puts forward precise control and pressure maintenance of the screw conveyor by the working condition. Moreover, if the seal abates when EPBS excavates washy soil layer, casualty as spewing and so on will occur. Therefore, the study of the precise control and pressure maintenance of Shield screw conveyor is of great significance.The soil modified exhibits Non-Newtonian Liquid Features obviously. It possesses a certain shear strength in Rheological Experiment, which approaches the Bingham model. CFD software-Cfdesign is used to simulate the Flow Field inside the screw conveyor in this paper. The flow and pressure status with various parameter is calculated, so that the key factors of the Sealing Performance and transmission capacity can be found. The conclusions will be useful to guide the design and applications in engineering practice.On account of the structure, dimension and collocation of screw conveyors is different in kinds of EPBS, Modeling and Simulation is processed in a specific condition in this paper.