Numerical Investigation of Pressure and Impulse Distributions at Tunnel Portals under Varying Explosive Charge Weights in Long-Span Tunnels

Hun Ji; WooSeok Kim

doi:10.7734/COSEIK.2025.38.6.363

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2025 Vol.38, Issue 6 Preview Page Next Page

Research Paper

Numerical Investigation of Pressure and Impulse Distributions at Tunnel Portals under Varying Explosive Charge Weights in Long-Span Tunnels 장대형 터널 입구에서 폭약량 변화에 따른 압력 및 충격량 분포 특성에 대한 수치해석

31 December 2025. pp. 363-370

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Abstract

The present study conducts a numerical analysis of the distribution of blast load propagation inside a long tunnel following a trinitrotoluene (TNT) explosion at a portal. This study focuses on the transition of the Mach stem into a planar wave as it enters and on quantifying the attenuation trends of peak pressure and impulse along the interior of the tunnel. A series of numerical simulations were conducted using ANSYS AUTODYN 2023R1, a hydrocode specifically designed for modeling high-explosive blasts. The computational model consists of a straight tunnel with a cross-sectional area of 25m². Four TNT charge weights of 10, 50, 100, and 500kg were considered, and measurement points were placed along the tunnel centerline to record blast responses at multiple distances. To enable consistent comparisons across different charge weights, the scaled distance parameter Z = D/W was introduced, where D denotes the standoff distance, and W denotes the charge weight. The results indicate that although the absolute values of pressure and impulse vary with charge weight, their normalized responses exhibit a similar attenuation trend with respect to scaled distance. These findings highlight the consistent spatial decay behavior of blast loads under portal explosion conditions and provide useful reference data for evaluating hazard ranges, planning protective measures, and improving blast-resistant tunnel design.

Keywords

tunnel portal explosion

planar shock wave

peak pressure

peak impulse

numerical estimation

본 연구는 장대형 터널 입구에서 발생한 TNT 폭발로 인해 터널 내부로 전달되는 충격파 하중의 거리별 분포를 수치적으로 분석하였다. 특히 마하파가 평면파로 전이되는 구간에서 최대 압력 및 충격량의 감쇠 특성을 정량적으로 규명하는 데 중점을 두었다. 해석에는 고폭발물 해석에 특화된 도구인 ANSYS AUTODYN 2023R1을 사용하였으며, 25제곱미터 정사각 단면을 가진 직선형 터널을 대상으로 TNT 중량 10kg, 50kg, 100kg, 500kg 조건을 적용하였다. 터널 중심선 상의 관측 지점을 통해 데이터를 수집하고, 거리(D)를 폭약 중량(W)으로 나눈 환산 거리(Z = D/W)를 도입하여 중량 간 비교를 수행하였다. 분석 결과, TNT 중량에 따라 절대 응답 값은 달랐으나 정규화된 축에서는 최대 압력과 충격량이 유사한 감쇠 경향을 나타냈다. 이러한 결과는 터널 입구부 폭발 시 발생하는 하중 분포가 환산 거리 기준으로 일정한 패턴을 갖는다는 점을 보여주었으며, 향후 방호 설계, 위험 구역 산정 및 폭발 피해 예측 등에 활용 가능한 기초자료를 제공할 수 있을 것으로 기대된다.

키워드

터널 입구 폭발

평면파

최대 압력

최대 충격량

수치해석 기반 추정

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Information

Publisher :Computational Structural Engineering Institute of Korea
Publisher(Ko) :한국전산구조공학회
Journal Title :Journal of the Computational Structural Engineering Institute of Korea
Journal Title(Ko) :한국전산구조공학회 논문집
Volume : 38
No :6
Pages :363-370
Received Date : 2025-08-11
Revised Date : 2025-09-01
Accepted Date : 2025-10-16
DOI :https://doi.org/10.7734/COSEIK.2025.38.6.363

Journal of the Computational Structural Engineering Institute of Korea ISSN:1229-3059(Print) 2287-2302(Online) 한국전산구조공학회 논문집

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