5.3 Calculation and Analysis of the Mud Circulatio...
With the construction of a large number of river-crossing and sea-crossing tunnels in China，slurry pressurized shield has been more and more widely used.The slurry shield carries the excavated residue soil to the ground slurry separation system by inputting mud，and forms a set of circulation system.
The mud circulation system is composed of inlet pump，discharge pump，flowmeter，control gate valve，inlet and discharge pipeline，and ground mud separation system.The soil sand excavated by the shield enters the slurry tank，and mixes with the slurry to form high-density slurry，which is pumped by the slurry pump（slurry pump）to the slurry separation system for processing.The slurry treatment system of the separated slurry shield consists of a black cyclone screening system and a sedimentation tank.The slurry separation process is shown in Fig.5.34.
On the basis of existing equipment，it is one of the key problems to be solved before construction whether the sand and residue carried in the slurry can be effectively separated to prevent the deposition of sand and stone in the slurry tank.By calculating the slag carrying capacity of the discharge pipe under normal construction conditions，the mud sampling at different separation stages is tested and analyzed to demonstrate whether the composition of the screening system can meet the separation requirements.