SQUARE JOINT INSTALLATION HOLE AND SQUARE JOINT DEVICE STRUCTURE OF MANHOLE IN EARTHQUAKE-RESISTANCE IMPROVING METHOD

PROBLEM TO BE SOLVED: To provide an earthquake-resistance improving method in non-excavation work of an existing pipe which can lessen deterioration in strength caused by the use of a commercially available compact cutting-off machine in the conventional cutting work for securing a joint-installation space in a pipe connection of an existing manhole wall. SOLUTION: In the earthquake-resistance improving method, it becomes possible to secure the joint-installation space by cutting in a rectangular shape by a straight-line cutting method which forms a rectangular shape with very little deterioration in strength of a manhole wall surface concrete by the cutting with the compact cutting-off machine 1. Then the square joint having a square outside shape is installed and constructed in the joint-installation space of the sewerage pipe connection 12. The installation of a circular hole installation specification joint is made possible by converting the external shape of a joint-installation part by placing a special-purpose square joint and a square adaptor in the square joint-installation space. COPYRIGHT: (C)2010,JPO&INPIT