Stability evaluation during mountain tunnel excavation considering spatial heterogeneity of geomechanical properties

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14382
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 25020:Safety engineering-related
• Research Institution: Matsue National College of Technology
• Principal Investigator: Okazaki Yasuyuki 松江工業高等専門学校, 環境・建設工学科, 准教授 (50806081)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 山岳トンネル / 空間的不均質性 / 地盤物性 / 数値解析 / 安定性評価

Outline of Final Research Achievements

In this study, the tunnel excavation analyses considering spatial heterogeneity of geomechanical properties was carried out to contribute to advancement of mountain tunnel design by numerical analysis. the effects of degree of heterogeneity and difference in design conditions in heterogeneous ground on tunnel stability during tunnel excavation were evaluated.
As a result, it was possible to calculate the probability of exceeding the critical shear strain that is stability index of mountain tunnels for each analysis case. Based on these results, it was considered that if the degree of heterogeneity and design conditions could be grasped in advance, it was possible to easily estimate the collapse risk of tunnel and utilize the results of this study for judgment on design change.

Free Research Field

トンネル工学

Academic Significance and Societal Importance of the Research Achievements

現状の数値解析を用いた山岳トンネルの設計は，地盤物性の空間的な不均質性がトンネルの安定性に及ぼす影響に関するリスク評価を十分にできていないと考えられる．実際に近年でも，数値解析による設計時の地盤物性の空間的な不均質性に関する評価不足が山岳トンネルにおける事故発生要因の1つとなっている場合がある．
そこで，本研究では，地盤物性の空間的な不均質性を考慮したトンネル掘削解析を実施し，不均質地盤におけるトンネルの崩壊リスクを簡易的に推定できるようにした．これを活用することで，地盤物性の空間的な不均質性に関するリスク評価をより詳細に実施できるようになると考えられる．