shield machine

Shield machine is a kind of tunnel boring machine using shield method. The shield construction method is to construct (lay) the shield of the tunnel while the boring machine is driving, which is different from the open-cut construction method.

Internationally, the generalized shield machine can also be used in rock strata, but it is different from the open (non-shield) tunnel boring machine. In our country, it is customary to call tunnel boring machine used in soft soil stratum as (narrow sense) shield machine, and TBM used in rock stratum as (narrow sense).

According to the working principle, shield machines are generally divided into hand-dug shield, extrusion shield, semi-mechanical shield (local air pressure and global air pressure) and mechanical shield (open-chest cutting shield, air pressure shield, slurry pressure shield, earth pressure balance shield, hybrid shield and special-shaped shield).

Knowledge expansion:

Shield machine is a kind of tunnel boring machine using shield method. The shield construction method is to construct (lay) the shield of the tunnel while the boring machine is driving, which is different from the open-cut construction method. Internationally, the generalized shield machine can also be used in rock strata, but it is different from the open (non-shield) tunnel boring machine.

In our country, it is customary to call tunnel boring machine used in soft soil stratum as (narrow sense) shield machine, and TBM used in rock stratum as (narrow sense).

Part of tunnel boring machine adopts shield method, and the other part adopts cut and cover construction. For example, the full-face double shield rock tunnel boring machine (TBM) independently developed by China Railway Construction Heavy Industry Co., Ltd. itself has double shields, so there is no need to build (pave) the "shield" of the tunnel, that is, there is no need to lay pipe pieces, but it integrates excavation, support and slag discharge, which can realize the one-time forming of the tunnel.

The basic working principle of shield machine is that a cylindrical steel member pushes forward along the tunnel axis to excavate soil. The housing of the cylinder assembly is a shield.

It acts as a temporary support for the excavated unlined tunnel section, bearing the pressure of the surrounding soil layer and sometimes the groundwater pressure to keep the groundwater out. Excavation, dumping and lining are carried out under the cover of shield.