Application principle
With shield tunneling construction machine with a high degree of automation, saving manpower, construction speed, first into the hole, not climate, excavation of land subsidence can be controlled to reduce the impact of buildings on the ground and the excavation under water It does not affect water transportation and other features, a long hole in the tunnel line, depth at large, with a shield machine construction more economical and reasonable.
The basic operating principle of shield machine is a cylinder of steel components along the tunnel axis side forward edge of soil excavation. The cylinder assembly housing that is shield, it plays the role of temporary support has not been excavated tunnel lining segments withstand the pressure of the surrounding soil, groundwater and sometimes withstand pressure and will stand in the groundwater outside. Excavation, soil, lining and other operations carried out under cover of the shield.

Demand characteristics
Slurry shield machine by pressing mud or mud (usually bentonite suspension) to stabilize the excavation face, behind which there is a seal cutter separator between excavation face and form mud room, which is full of mud, excavation of soil material mixed with mud from the mud pump delivered to the separation plant outside the cave, after the separation of the mud reused. EPB shield machine is the soil material (necessary when adding foam to soil improvement) as the excavation face stable medium, forming mud room between the separator and the excavation face late knife, rotating cutter Excavation increase so that the soil material, then rotate the soil material shipped out by the screw feeder transport, indoor clay soil pressure by rotating cutter head the excavation speed and output screw feeder unearthed amount (rotation speed) can be adjusted.
According to different classification micro-tunneling shield excavation methods can be divided into: open, mechanical cutting style, grid type, and extrusion and the like. In order to reduce the formation of shield construction disturbance, can be driven by means of the jack shield to make the incision penetration soil, then soil excavation and transportation in the incision