Study On Modeling And Simulation Of Shield Earth Pressure Balance System

Earth pressure balance (EPB) shield is kind of engineering machine used for underground excavation, which is primary used in shield tunneling. The stability of cut surface is ensured by EPB system of EPB shield. EPB system is a key system to the EPB shield and its performances directly affect the construction quality of shield. At present the study on EPB system is focus on several relatively independent regions. While research on the whole characteristic of shield EPB system is relatively less because it generally requires lots of investment in equipments to perform on site test or experiments of physical model which sets back the process of research. Therefore design and analysis of shield EPB system can but depend on engineering experience. So the purpose of this thesis is to study the characteristic of shield EPB system, with the safe, economic, fast, effective way by the simulation of shield EPB system, and offer certain reference for improving the performance of shield EPB system.It's difficult to establish the mathematical model of shield EPB system directly. Therefore a mathematical model of electro-hydraulic simulation system of EPB system (hereinafter refer to as EHSS) is built up first and then mathematical model of shield EPB system is established on basis of the similarity between EHHS and shield EPB system.First, a mathematical model of EHSS is built up by using the theory of power bond graph. Then the validity of the EHHS mathematical model is proven by comparing the response of EHHS and its mathematical model under various work condition,.On the basis of the EHHS mathematical model, a new mathematical model of excavation chamber is build up according to the theory of soil mechanics. And the mathematical model of screw conveyor is improved by mechanical analysis based on the theory of screw conveyor and screw extruder. The mathematical model of shield EPB system is established after some local adjustment on the original one.By using the parameters of a shield, the check experiment between EHHS and the mathematical model of EPB system is done. The acquired dynamic simulation results show the feasibility and validity of the mathematical model of EPB system.With the simulation of the mathematical model of EPB system, the effect of earth pressure and friction coefficient of soil on the performance of screw conveyor are investigated. Some results were found and can be applied to improve the ant-jamming capability of shield EPB system.In summary, this thesis presents the complete dynamic modeling and simulation research of EHHS and shield EPB system. The research results offered certain reference for further investigating of the characteristic of shield EPB system, which may be useful for improving the design of shield EPB system and earth pressure control.