Do earth pressure balance shields require mud and water separation?

• Jul 21, 2022
• There are two types of metro shield: earth pressure balance shield and mud water balance shield. The earth pressure balance shield does not require mud and water separation, as it is essentially a soil excavation, while the mud and water ...

There are two types of metro shield: earth pressure balance shield and mud water balance shield.

The earth pressure balance shield does not require mud and water separation, as it is essentially a soil excavation, while the mud and water balance shield requires mud and water separation.
 

 

The principle of mud-water balance shield machine is to mix the relatively wet soil at the front of the shield into mud, and then pump out the mud to form a tunnel. The extracted mud needs to be separated from the water for environmental reasons, so that the water can be reused. The mud and water separation requires the use of mud and water separator, which is divided into three layers, sieving out the stones and soil pieces of different particle sizes and then filtering them by pressure to realize the separation of soil and water. This avoids the pollution caused by the direct discharge of mud and water, and also realizes the reuse of water, and the separated soil can also reach the safe discharge standard, so that the waste residue can be properly disposed of. Compared with earth pressure shield machine, obviously the structure of mud and water balance shield machine is more complicated and the mud and water separator also takes up a large area, so it is relatively less applied, but in wetter strata, such as Shanghai and other coastal areas, generally only mud and water balance shield machine can be used.