| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an expansion construction method for a manhole, excellent in work efficiency, and capable of widely securing an internal space (effective space) after expansion without causing insufficient strength in an expansion part.SOLUTION: In the inside of a manhole, a propulsion unit is installed in an expansion direction by materials carried in from a manhole neck part and the steel box with an upper part formed in the shape of a grating is assembled. The steel box is arranged on the propulsion unit, with an opening of the steel box being directed in the expansion direction. A manhole wall in the expansion direction is demolished before or after the installation of the propulsion unit and the assembly of the steel box, and boring is performed inside the steel box while propelling the steel box by the propulsion unit. After boring of a predetermined length is carried out, the arrangement of reinforcement is provided in the bored hole and a concrete form is attached. Then, concrete is supplied into the concrete form, and the filling state of the concrete is checked from above the shape of the grating. Thereafter, the concrete is cured and then the concrete form is removed.</p> |
