WIDENING DEVICE FOR EXISTING TUNNEL

PROBLEM TO BE SOLVED: To widen an existing tunnel with a road or the like kept in service entirely by applying the constitution that a rack having a lower part opened in such a state as passable along a tunnel axis direction is supported with a telescopic pedestal, and a passage frame is erected forward and backward of the rack in a tunnel axial direction. SOLUTION: Each type of a breaking device, an excavation device, a spraying device, a transportation device and the like is mounted on a rack 1. Then, a forward passage frame 4 is inserted in an existing tunnel as a widening object and a support 31 is extended on the operation of a jack. As a result, a support member 3 is laid on the external surface of the rack 1. Thereafter, the natural ground outside the lining 51 of the existing tunnel is excavated, with the lining 51 maintained. This excavation process takes place on the operation of excavators on a work floor 11 and a side work floor 12, and the exposed lining 51 of the existing tunnel is broken by a crusher such as a breaker. Furthermore, after the removal of the existing tunnel, a lining work for a new tunnel 6 is carried out outside the removed tunnel.