Control Model Of Earth Pressure For Shield Tunneling Based On Neural Network

The control of land subsidence is always an important aspect of Shield technology research operating the complex shield. And it is also a major problem of Shield technology because of the bad control result could lead to some accident disaster like surface subsidence. The decisive factor of land subsidence is the earth pressure of the shield's sealed cable. Therefore, it is very important to maintain the balance between earth pressure in the sealed cable and earth pressure of excavated surface. However, some difficulties like the complexity of shield construction process, the obvious fluctuation of relative geological conditions and orbit conditions or operation of construction, sometimes, they even become random and fuzzy, and it also has relevancy and couplings among those subsystems in the shield system. It is hard to describe the construction process by specific mathematic model, and the control of Earth Pressure Balance Shield stays at experience level. In order to achieve automatic control of earth pressure balance shield, the establishment of earth pressure shield tunneling system control model is very necessary. Based on this, this thesis has done researches as follows:Firstly, this paper designs the control system of Earth Pressure Balance Shield and analysis the operating principle and mentality of design about the control system of Earth Pressure Balance Shield, specially, study the coordination control problem among the cutter head subsystem, the propulsion subsystem and the slag subsystem. Secondly, based on mechanism analysis, get the conclusion that the main effected parameters of earth pressure are cutter head speed, advanced speed, thrust and screw conveyor speed. And establish the formulas of earth pressure and these parameters. This provides a basis of the balance control of the sealed cable's earth pressure. Based on this, create a control model of Earth Pressure Balance Shield by BP Neural Network, which make cutter head speed, advanced speed, thrust and screw conveyor speed as inputs and sealed cable's earth pressure as output, and make the cable's earth pressure track the expected earth pressure by means of solving this model to get the optimal screw conveyor speed. At last, train and verify this control model with the field construction data. The simulation result shows that this control model of earth pressure balance could satisfy the requirement of the control of Earth Pressure Balance and it is more precise than the manual control. The conclusion has some directive significances about the research of the automatic control of Earth Pressure Balance Shield.