Shield machine, the full name of the shield tunnel boring machine, is a tunnel boring special engineering machinery, modern shield boring machine set optical, mechanical, electrical, hydraulic, sensing, information technology in one, with the excavation and cutting of the soil, conveying soil ballast, assembling the tunnel lining, measuring guiding and correcting the deviation of the function, involving geology, civil engineering, machinery, Mechanics, hydraulics, electrical, control, measurement and other disciplines of technology, and according to different geological "tailor-made" design and manufacturing, reliability requirements are extremely high. Shield tunneling machine has been widely used in subway, railroad, highway, municipal, water and electricity tunneling projects. Shield machine is mainly categorized as: open type, mechanical cutting type, mesh type, extrusion type.