Although a spherical tunnel face has been reported to enhance the stability of tunnels where the tunnel is excavated using Sequential Excavation Method, the effect of the shape of the tunnel face on the deformation behavior, mechanical stability, and ease of construction for the tunnel has yet to be quantitatively clarified.
The Shin-Takarahama Tunnel was excavated through granite by full-face advanced drill and blast while varying the shape of the spherical tunnel face and blasting pattern.
As a result, full-face advanced drill and blast in combination with a spherical tunnel face enhanced tunnel stability and improved the efficiency of work in front of the tunnel face. This paper clarifies the characteristics of mechanical behavior of a tunnel with a spherical tunnel face and its ease of construction so that the effectiveness of the spherical tunnel face method is hereby quantitatively verified.
