Flexible joint connecting device of precast body segment, precast body segment joining-type underwater tunnel construction method using same, and underwater tunnel constructed thereby

A method of constructing an underwater tunnel by coupling precast concrete segments (2), comprising:

• forming a tunnel module by integrally connecting a plurality of floating precast concrete segments (2) in a state where both longitudinal ends of the precast concrete segments (2) are sealed, wherein a plurality of tunnel modules are formed to float and are temporarily connected to each other by a flexible joint connecting device (3) that allows vertical displacement;
• submerging a first tunnel module (21) positioned close to a end portion (1) in water among the plurality of tunnel modules;
• when a rear end of the submerged first tunnel module (21) faces the end portion (1), temporarily connecting the rear end of the first tunnel module (21) to the end portion (1) by using the flexible joint connecting device (3);
• submerging a second tunnel module (22) successive to the first tunnel module (21) in water;
• connecting and joining the end portion (1) and the first tunnel module (21) in a perfect watertight manner to be integrated;
• and
• submerging a third tunnel module (23) successive to the submerged second tunnel module (22) in water, and connecting and joining two precast concrete segment assemblies in a perfect watertight manner to be integrated, which is repeated such that a plurality of tunnel modules are integrally coupled to construct an underwater tunnel,
• wherein the flexible joint connecting device (3) for temporarily connecting the tunnel modules and temporarily connecting the rear end of the first tunnel module (21) to the end portion (1) is configured to include first and second joining modules (31a, 31b) respectively coupled to a pair of precast concrete segments (2) facing each other of the tunnel modules to be temporarily connected and connected to each other by an expansion/contraction device (32),
• wherein each of the first and second joining modules (31a, 31b) is integrally coupled to the precast concrete segment (2) while surrounding an outer side of the precast concrete segment (2),
• wherein the expansion/contraction device (32) is an expandable and shrinkable member that is longitudinally disposed between the first and second joining modules (31a, 31b), and the first joining module (31a) includes a hinge fixing member (320) so that one end of the expansion/contraction device (32) is hinged to the hinge fixing member (320) to be vertically rotatable,
• wherein the second joining module (31b) includes an end fastening member (321) that is vertically rotatable, and
• wherein as the pair of precast concrete segments (2) facing each other of the tunnel modules to be temporarily connected approach toward each other, the other end of the expansion/contraction device (32) is fastened to the end fastening member (321) so that the first and second joining modules (31a, 31b) are integrally connected by the expansion/contraction device (32), whereby the pair of precast concrete segments (2) respectively having the first and second joining modules (31a, 31b) are connected to be vertically bendable with respect to each other, and, when the expansion/contraction device (32) is contracted, the precast concrete segments (2) are pulled toward each other so that ends thereof come into contact.