In the tunnel entrance hood which is provided in the input/output opening of the tunnel entrance hood null tunnel which decreases

摘要

PROBLEM TO BE SOLVED: To reduce the intensity of low frequency sound radiated by high speed vehicles in going in/out a tunnel by providing notched parts or an open end in an outer side vehicle entrance/exit end of a buffer work and providing a throttle part in a tunnel side vehicle entrance/exit end. ;SOLUTION: A buffer work provided in an entrance/exit of a tunnel is provided with notched parts 2, 2 formed by notching parts of a lining 1 having openings 4, 4 in an outer side vehicle entrance/exit end of the buffer work or an open end 2' gradually increasing the cross section towards the outer side vehicle entrance/exit end. A throttle part 3 gradually reducing the cross section from the principal section of the buffer work to the principal section of the tunnel is provided in the tunnel side vehicle entrance/exit end of the buffer work. This constitution can reduce the intensity of the low frequency sound directly radiated to the outside, when high speed vehicles go in/out between the outside and the buffer work or between the buffer work and the tunnel.;COPYRIGHT: (C)2000,JPO