Abstract: The Tjoint has complex forces and is easy to cause safety accidents. To investigate the weakening effect of the main tunnel segment and ensure the safety of shield tunneling, a cutting test is conducted on the shield cutterhead used in mechanical connection channel, the excavation and cutting process of the concrete segment at the launching end is simulated, and the change of the cutting force of the tool at different moments and relationship curve and the distribution law of internal forces of segments and bolts under different working conditions are revealed. The following conclusions are obtained:  (1) The greater the cutting thickness and speed of the tool, the greater the cutting resistance, the more obvious cracking of the concrete and the serious tool wear. The greater the strength of the base concrete, the less damage to the surface of the concrete during cutting. (2) The cutting of tube segments has a greater impact on the bolts of a same ring, and less impact on the bolts on the side. As the cutterhead rotates and advances, the displacement of the tube segments changes, and the displacement of the bolt connection points gradually increases. When the cutterhead drills out of the segment, the displacement of the concrete segment and the internal bolt gradually stabilizes. (3) Changing the strength needed to cut the segment has little effect on the deformation of the tunnel. After changing the cutting strength, the displacement of the tunnel segment increases, but the influence is relatively little, and the structure is still in safe.

Key words:  , Tjoint, connection gallery, mechanical excavation method, segments, cutting test