To simply vary the surrounding area of a protection fence even in the base the size of a road opening section differs in an excavation site and to excavate up to the depth corresponding to the capacity of an excavator to promote work efficiency.
A protection fence 20 fixes fixed side frame bodies 22 and 23 on both right and left sides of the front frame body 21 backward, and holding metal fixtures 24 are roughly horizontally projected to the outsides of lower edge sections of the fixed side frame bodies 22 and 23 respectively. The lower surfaces of auxiliary side frame bodies 27 and 28 are mounted on the holding metal fixtures 24 in a slidable manner in the directions of front and rear, and the auxiliary side frame bodies 27 and 28 are so formed that they can be moved back and forth along both right and left fixed side frame bodies 22 and 23. The lower parts of the rear ends of both right and left auxiliary side frame bodies 27 and 28 are connected to each other with a joint member 29, and groove sections 30 are provided to the insides of the rear ends of the auxiliary side frame bodies 27 and 28 in the vertical direction. The rear side frame body 31 is dropped from the upper direction of both right and left groove sections 30, and the rear side frame body 31 is mounted to the protection fence 20 in a detachable manner.
ONO HIROKATSU
IKEDA TATSUYA
FUCHIGAMI YUKIHIKO
