This type of shield is equipped with a closed partition on the back side of the cutter head of the mechanical shield, and the space between the partition and the cutter head is named the mud silo. The muddy water made by mixing water, clay and its additives is pressed into the muddy water silo through the conveying pipeline. When the muddy water fills the whole muddy water silo and has a certain pressure, a muddy water pressure chamber is formed. The stability of the excavation face can be maintained by the pressurizing action of the muddy water and the pressure maintaining mechanism. When the shield is advanced, the soil and sand cut by the rotary cutter head are stirred by the stirring device to form high-concentration muddy water, which is sent to the ground mud-water separation system by fluid conveying, and the ballast soil and water are separated and sent back to the mud-water silo. The main features of the pressure-balanced shield method. Because it is the muddy water pressure that stabilizes and balances the cutting surface, it is named muddy water pressure balance shield, or muddy water shield for short.
The mud-water pressurization shield method refers to injecting mud into the shield excavation, and balancing the pressurization and formation pressure to ensure the stability of the soil on the excavation surface.
When the shield is propelled, the excavated taxi enters the mud chamber at the front of the shield, and is stirred by a stirring device or broken by a crushing device. The high-concentration mud water after mixing and crushing is pumped to the ground by a mud pump, and the mud water is separated on the ground. , Through the action of the mud pump, the slurry with the appropriate proportion is sent to the mud water silo of the shield, so that the slag is continuously discharged, purified and used.
Slurry shield is mainly used for excavation across rivers, seas and unstable strata. When excavation requires strict control of disturbance to the stratum, mud shield is generally used.
