WIDTH WIDENING METHOD AND BLASTING PROTECTION CONSTRUCTION FOR TUNNEL IN MOUNTAIN

摘要

PROBLEM TO BE SOLVED: To carry out a width widening work for the cross section of tunnel safely and quickly from an old tunnel to a new tunnel by using hot line. SOLUTION: After drilling a blasting hole with a drilling machine installed on the side of a new tunnel 3 at a cross section widening portion 4 as a boundary between the old tunnel 2 and the new tunnel 3, a cross section between the outer periphery of a protector 11 and the lining concrete of the old tunnel 2 is closed at the front protection partition wall 7 provided at the side of the old tunnel 2 cramping the cross section width widening portion 4. At the rear protection partition wall 8 provided at the side of the new tunnel 3 cramping the cross section width widening portion 4, a cross section between the outer periphery of the protector 11 and the lining concrete 5 of the new tunnel 3 is closed and a blasting surrounding portion 15 is formed. Within this blasting surrounding portion 15, the blasting work is carried out.