How to build an invert in an existing tunnel

摘要

To provide an invert construction method to an existing tunnel capable of ensuring safety of vehicle traffic with work efficiency.SOLUTION: An invert construction method comprises: restricting traffic on a left side of a road surface 2 (A-A); constructing an U-shape groove 12 located on a left side of a tunnel and in a tunnel axis direction at a position near a center of the tunnel using an opencut self-travelling Messer shield machine 20 (A-A, B-B); constructing an invert 11 within the U-shape groove 12(B-B to E-E); and constructing the invert 11 (D-D) by excavating the ground base in a remained part of the left side of the tunnel (C-C) to restore the road surface 2 of the left side of the tunnel (E-E). After that, the restriction of the traffic is changed to a right side from the left side of the road surface 2, constructing the invert 11 by excavating the ground base on the right side of the tunnel to restore the road surface 2 of the right side of the tunnel. The U-shape groove 12 functions as a protecting wall upon excavating the left and right of the tunnel, and the U-shape groove 12 is previously constructed before excavation regardless of an excavation progress, resulting in an efficient workability.SELECTED DRAWING: Figure 2