NSM-CFRP strengthening of lining-concrete for renewal of road tunnels

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04213
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22010:Civil engineering material, execution and construction management-related
• Research Institution: Yamaguchi University
• Principal Investigator: Yoshitake Isamu 山口大学, 大学院創成科学研究科, 教授 (10335771)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 補強 / トンネル / FRP / 覆工 / コンクリート

Outline of Final Research Achievements

This study evaluated the load-carrying capacity of tunnel lining concrete (TLC) models strengthened by NSM-CFCC and investigated the effectiveness of the strengthening system for TLC. TLC models bonded with a carbon-fiber sheet (CFS), and NSM-CFCC-strengthened TLC models, and two types of NSM-CFCC TLC models were tested. The results revealed that the TLC member was not perforated by a flexural crack, even in non-strengthened concrete, owing to the arch effect. The load-carrying capacity of the NSM-CFCC TLC was remarkably higher than that of the reference and CFS strengthening models. A finite difference analysis (FDA) for the loading test was also performed using commercial software FLAC3D. The numerical simulation results were found to be in good agreement with the cracking behavior of the strengthened TLC members observed in the experiment. These results suggested that the strengthening system using NSM-CFCC is effective for the TLC.

Free Research Field

土木工学

Academic Significance and Societal Importance of the Research Achievements

道路トンネルには，床版取り替え工事のようなリニューアル技術が確立していないのが現状である．さらに将来にわたって老朽劣化していく覆工コンクリートをリニューアル（更新）と同等レベルにまで補強できる技術はほとんどみられない．これまで構造部材として建設されていないトンネル覆工コンクリートが，トンネル本体の使用性・安全性にまで影響してきていることから，これを適切に補修・補強していく技術が求められるようになっている．現状では補修で延命化を図る技術はあるものの，リニューアル相当レベルまでのトンネル構造全体の安全性・耐久性を高める技術は未だ確立していない．