Finding 3-d maximum key blocks on unrolled joint trace maps of tunnel surfaces
G. Shi, R.E. Goodman · 2020
This paper presents a practical and intuitive method of finding all unsafe areas on tunnel surfaces. The unsafe areas consist of the faces of 3-d key blocks. Each such face is delimited by joint traces. The cylindrical surface of the tunnel and the joint traces on it can be unrolled onto a plane; In so doing, the joint traces became curved lines and their intersections produce curved polygons, which can be computed. Tunnels with general shapes are represented analytically. The joint traces used by this method are generated statistically and unrolled together with the cylindrical tunnel surface. However, this method can also be applied to actual joint traces as mapped on exposed tunnel walls.