In recent years

the slurry shield method has been extensively used for tunneling under seas or rivers. In the process of slurry shield construction

opening the chamber under air pressure has always been a high-risk and difficult task. The key to the success of opening the chamber under air pressure lies in the filter cake airtightness property. However

there has been less theoretical research on the mechanism of failure of filter cake airtightness property

airproof time and its influencing factors. Therefore

considering the effects of air pressure and pore water

we establish a transient mechanical model "percolation initiation–failure under air pressure" of filter cake based on multiphase flow theory

and propose a method for predicting water discharge mass through filter cake and airproof time under air pressure. Then

we conduct the laboratory filter cake airproof test to verify the applicability of the proposed theoretical approach. Finally

the influences of air pressure

stratigraphic parameters

filter cake thickness

slurry shear strength and other parameters on filter cake airproof time are discussed

and the results reveal that the airproof effect mainly depends on the filter cake under air pressure

followed by infiltration zone. This study can provide some reference for the safety of opening chamber under air pressure in slurry shield.