Abstract: Tunnel boring machine is a kind of construction machinery which includes machine, electricity, hydraulic, monitoring and control and civil engineering. The earth pressure balance control mode of a EPB shield used in Beijing Subway is analyzed. The control principle is making a proper balance between excavation rate and discharge rate, and making a balance between pressure of chamber and excavation surface. It can reduce strata disturbance and control ground surface settlement. In order to implement earth pressure balance, we should make screw cooperated with propulsion system.

Key words: shield, EPB shield, propulsion system, screw system, autocontrol