| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a highly watertight joint tunnel, which consists of precast concrete blocks, eliminates the necessity for concrete casting at site, saves man-hours for that work, enables wire laying immediately after installation, redusce construction lead time and reduces construction cost and, in addition, eliminates edges which are formed on the joint parts of the blocks and damage the laid wires and, further, enables a highly watertight structure. SOLUTION: A precast concrete block 1 which has a specified length has a proper number of conduits 2 embedded in its square cross section. Both the end parts of the conduit 2 have inclined inner circumferences 11, which open outwards to enlarge the conduit diameters. The inclined inner circumference 11 is continuous with the hole 7 of a concrete ground, having an inclined inner circumference 12. When a plurality of the precast concrete blocks 1 are connected in a longitudinal direction, a sealing packing 15 which has inclined surfaces 17 and 17 pressed against or fixed to the inclined inner circumferences and is provided between the end surfaces 1a of the blocks 1.</p> |
