2026 Volume 51 Pages 9-1-9-11
In shield tunneling projects, such as those for road construction, which are subject to the Act on Special Measures concerning the Public Use of Deep Underground (hereinafter referred to as the “Deep Depth Method”), it is necessary to consider (1) loads from large buildings in high-rise building projects in commercial areas, (2) the effects of adjacent construction when parallel tunnels are built, and (3) fire resistance in road tunnels. Conventional RC segments, therefore, cannot provide sufficient structural performance. In these cases, expensive composite segments are used, leading to major increases in construction costs. We have developed RC segments made of ultra-high-strength concrete as a less expensive alternative to composite segments. This contributes to reducing costs and streamlining construction works in shield tunneling projects where the Deep Depth Method is applied.
This report describes the manufacturing and strength testing of ultra-high-strength concrete conducted for the development of ultra-high-strength RC segments, along with evaluations of fire resistance, durability, and crack initiation caused by delayed ettringite formation. It also reports on the verification of structural performance using flat specimens extracted from full-scale ultra-high-strength RC segments.
