When the shield tail exits the tunnel, the speed must be stable, because the support above the tunnel is originally supported by the shield tail. In this process, grouting should be followed up at the same time, but the role of rubber curtain cloth at the entrance can make the slurry fill the gap between the shield tail and the outer diameter of the segment. In addition to normal infiltration into the stratum at the mouth of the cave, the mud is partially lost, which may cause a cavity above the mouth of the cave and cause ground subsidence. If it is not well controlled, it may even cause landslides. Therefore, as soon as the shield comes out of the tunnel, the secondary grouting must keep up and reach the due pressure according to the technical instructions.