| CPC E21D 9/06 (2013.01) [E21D 9/112 (2013.01); E21D 9/10 (2013.01)] | 19 Claims |

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1. A tunnel excavation device comprising:
a front body section including a cutter head including a plurality of cutters, a cutter head support section supporting the cutter head, and a collapsing section provided to an outer circumference of the front body section, the collapsing section being configured to be collapsed toward an inside; and
a rear body section including a gripper section for obtaining a reaction force when excavating, the rear body section being disposed to a rear of the front body section,
the collapsing section including a circumferential edge plate disposed on a circumferential edge of the cutter head,
the circumferential edge plate being coupled to a side surface of the cutter head in a collapsible manner via a coupling section, and
the circumferential edge plate being collapsible by rotating about the coupling section from a first position in which the circumferential edge plate protrudes outwardly from the side surface of the cutter head to a second position in which the circumferential edge plate is disposed further inward than the side surface of the cutter head.
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