A study on the impact of major design factors on the ground settlement directly above the tunnels in trenchless construction methods

Man-Ho Kang; Hyeok-Sang Jeong; Sung-Woo Lee; Chae-Un An

doi:10.9711/KTAJ.2025.27.3.169

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2025 Vol.27, Issue 3 Next Page

Research Paper

A study on the impact of major design factors on the ground settlement directly above the tunnels in trenchless construction methods 비개착공법에서 터널 직상부 지반 침하에 대한 설계 주요 인자별 영향 연구

31 May 2025. pp. 169-191

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Abstract

In this study, a 3D numerical analysis was performed under conditions similar to those of an actual trenchless construction site to ensure the reliability of the trenchless construction method design. The parameters considered were surface traffic load (railway load), tunnel cross sectional ratio, overburden depth ratio, and unsupported tunnel length, which are key factors influencing surface settlement. The results indicated that surface settlement increases as the cross-sectional ratio decreases, the overburden depth becomes shallower, and the unsupported tunnel length increases. This suggests that larger excavation areas result in greater settlement, and shallow overburden conditions lead to more settlement due to a lack of arching effects. Furthermore, the maximum ground surface settlement occurred as soon as the tunnel face was removed. As excavation continued, the settlement gradually reduced, with negligible difference between the final excavation settlement and the predicted settlement at the completion stage. Based on these findings, the study analyzed the correlations between the major factors influencing ground surface settlement and proposed a predictive equation for surface settlement. To validate the derived equation, an analysis of variance was conducted, and hypothesis testing using the F-distribution was performed. The equation was further validated by comparing it with actual measurement data from various trenchless construction sites, confirming its high reliability. The proposed predictive equation can be used to select an appropriate trenchless construction method based on a given site’s structural and environmental conditions, predict ground surface settlement, and determine the critical overburden depth that ensures the stability of surface traffic. This would contribute to the design of safe and efficient trenchless construction methods.

Keywords

Trenchless construction method

Ground surface settlement

Overburden depth ratio

Tunnel cross section ratio

Unsupported tunnel length

본 연구에서는 비개착공법 설계의 신뢰성을 확보하기 위해 실제 비개착 공사 현장과 유사한 조건 하에서 상부 교통은 철도 하중으로 하고 단면비, 토피비, 무지보 굴진장을 지표 침하 요인의 매개변수로 하여 3차원 수치해석을 수행하였다. 그 결과 단면비는 적을수록, 토피고는 작을수록, 무지보 굴진장은 길수록 침하량이 큰 것으로 나타났다. 이는 굴착 면적이 넓을수록 침하량이 크고, 작은 토피고일수록 아칭효과가 없어 침하량이 큰 것으로 판단된다. 또한 터널 막장면의 제거와 동시에 최대 지표 침하량이 가장 크게 나타났으며, 굴착을 진행할수록 침하량은 점점 줄어들었으며, 최종 굴착 완료 시의 지표 침하량과의 차이는 미미한 것으로 나타났다. 상기와 같은 연구 결과를 통해 지표면 침하에 영향을 미치는 주요 인자들 간의 상관관계를 분석하여 지표 침하량 예측식을 제시하였다. 그리고 도출한 예측식을 검증하기 위해 분산분석을 실시하여 F분포를 이용한 가설 검증과 여러 비개착공법 적용 현장의 실제 계측값과 비교하여 검증을 하였으며, 그 결과 신뢰도가 높은 예측식임을 확인하였다. 따라서 본 연구를 통해 제시한 지표 침하량 예측식을 활용하여 현장의 구조적 조건과 환경적 조건에 적합한 비개착공법의 선정과 지표 침하량 예측, 그리고 상부 교통의 주행 안전성을 확보할 수 있는 한계 토피고를 산정하여 안전하고 효율적인 비개착공법을 설계하는데 기여할 수 있을 것이다.

키워드

비개착공법

지표면 침하

토피비

단면비

무지보 굴진장

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Information

Publisher :Korean Tunneling and Underground Space Association
Publisher(Ko) :한국터널지하공간학회
Journal Title :Journal of Korean Tunnelling and Underground Space Association
Journal Title(Ko) :한국터널지하공간학회 논문집
Volume : 27
No :3
Pages :169-191
Received Date : 2025-03-17
Revised Date : 2025-04-04
Accepted Date : 2025-04-04
DOI :https://doi.org/10.9711/KTAJ.2025.27.3.169

Journal of Korean Tunnelling and Underground Space Association ISSN:2233-8292(Print) 2287-4747(Online) 한국터널지하공간학회 논문집

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