All Issue

2026 Vol.36, Issue 2 Preview Page

Research Article

Comparative Analysis of Subsurface Cavity Risk Assessment Frameworks and Verification of Geomechanical Thresholds: Evidence from Urban Road Cavities in Busan, Korea

도로 하부 공동의 위험도 평가체계 비교 및 지반역학적 임계값 검증: 부산지역 공동 사례를 중심으로

Dohyung Lim12
,
Jeong-Gi Um3*
임 도형12
,
엄 정기3*
1PhD Candidate, Department of Energy Resources Engineering, Pukyong National University
2Assistant Manager, Road Safety Division, Urban Spatial Planning Bureau, Busan Metropolitan City
3Professor, Department of Energy Resources Engineering, Pukyong National University
1국립부경대학교 에너지자원공학과 박사과정
2부산광역시 도시공간계획국 도로안전과
3국립부경대학교 에너지자원공학과 교수
*Corresponding Author
30 June 2026. pp. 313-332
PDF XML Citation
Abstract

This study compares four representative repair-stage frameworks—those of Osaka, Seoul, KALIS (Korea Authority of Land and Infrastructure Safety), and the CDI (Cave-in Damage Index)—using 3,054 cavities confirmed by borehole investigation following ground-penetrating radar (GPR) surveys in Busan, Korea. The risk-grade distributions of the four frameworks were compared, and the geomechanical characteristics of each grade were examined using dimensionless cavity-geometry parameters. The frameworks differed substantially in classification, reflecting their distinct assessment philosophies: the KALIS framework was comparatively conservative, assigning more cavities to high-risk grades, whereas the Osaka and CDI frameworks applied a more selective classification, restricting the high-risk category to a narrower range of cavities. Cavity risk was governed primarily by the cover-depth-to-width ratio (η = ht/W) rather than by cavity size: high-risk cavities concentrated at η < 0.4 and low-risk cavities at η > 0.87, consistent with Kuwano’s experimental criterion and Rankine’s theoretical soil-arching limit, respectively. Odds-ratio analysis confirmed that cavities with η < 0.4 were significantly more likely to be classified as high-risk across all frameworks. These field-scale results indicate that η is an effective indicator for cavity risk assessment and maintenance prioritization.

Keywords
subsurface cavity
road sinkhole
risk assessment
geomechanical threshold
soil arching

본 연구는 부산 지역에서 지표투과레이더(GPR) 탐사 후 천공 및 공내영상조사를 통해 확인된 도로 하부 공동 3,054개를 대상으로 오사카(Osaka), 서울시(Seoul), 국토안전관리원(KALIS) 및 CDI (Cave-in Damage Index) 등 4개의 위험도 평가체계를 적용하여 위험 등급 분포 특성을 비교하였다. 또한, 공동의 형상 특성을 무차원 지표로 정규화하여 위험 등급과의 관계를 분석하고, 지반역학적 임계값의 현장 적용성을 검토하였다. 평가체계별 위험 등급 분포는 뚜렷한 차이로 도출되었는데, 이는 평가 목적과 의사결정 논리의 차이에 기인한다. KALIS 체계는 상대적으로 많은 공동을 고위험군으로 분류하는 보수적 특성을 보이는 반면, Osaka와 CDI 체계는 고위험군 분류 범위가 좁은 선별적 특성을 나타냈다. 공동의 위험도는 토피 깊이와 공동 폭의 비(η = ht/W)에 의해 주로 결정되었고, 고위험 공동은 η < 0.4에, 저위험 공동은 η > 0.87에 집중되어 각각 Kuwano의 실험적 임계값과 Rankine 토압 이론의 응력 아칭 한계에 부합하였다. 오즈비 분석에서도 η < 0.4 공동은 모든 평가체계에서 고위험 분류 가능성이 유의하게 높았는데, 이는 η가 도로 하부 공동의 위험도 평가와 유지관리 우선순위 결정의 핵심 지표로 활용될 수 있음을 지시한다.

키워드
도로 하부 공동
도로 함몰
위험도 평가
지반역학적 임계값
응력 아칭
References
1

BMC (Busan Metropolitan City), 2025, Busan City construction design guidelines (revised), 44p (in Korean).

2

KALIS (Korea Authority of Land & Infrastructure Safety), 2021, Underground safety inspection standard manual, 36p (in Korean).

3

Karasaki, Y., Kuwano, R., 2024, A study on the process of generation and expansion of subsurface cavities around the location of water leakage in sewer pipe joints, Japanese Geotechnical Journal, 17, 587-597 (in Japanese with English abstract).

10.3208/jgs.17.587
4

Kuwano, R., Kuwano, J., Sera, R., Ihara, T., Kozakai, N., 2023, Collapse risk evaluation of subsurface cavities and development of rational countermeasures considering road structure and cavity characteristics: Cavity behaviour in a full-scale test road, Japanese Geotechnical Journal, 18, 299-315 (in Japanese with English abstract).

10.3208/jgs.18.299
5

Lim, D.H., 2021a, Methods for estimating Cave-in Damage Index and deriving cavity management standards using it, Korean Patent No. 10-2259619, Korean Intellectual Property Office (KIPO) (in Korean).

6

Lim, D.H., 2021b, Implementation plan report for civil servant proposals (second half of 2020): Establishment of cavity management standards using Cave-in Damage Index (CDI), Road Planning Division, Busan Metropolitan City (in Korean).

7

Lim, D.H., 2024, Review report on revised cavity management standards of Busan City, Road Planning Division, Busan Metropolitan City (in Korean).

8

MLIT (Ministry of Land, Infrastructure, Transport and Tourism), 2012, Guidelines for cavity assessment (draft), Hokuriku Regional Development Bureau, Niigata (in Japanese).

9

MOLIT (Ministry of Land, Infrastructure and Transport), 2025, The 2nd national underground safety management master plan (2025-2029), 22p (in Korean).

10

Osaka Prefecture, 2016, Guidelines for pavement inspection in Osaka Prefecture, Transportation and Roads Division of Urban Development Bureau, Osaka (in Japanese).

11

Piggott, R.J., Eynon, P., 1977, Ground movements arising from the presence of shallow abandoned mine workings, In: Geddes, J.D. (Ed.), Proceedings of the Conference on Large Ground Movements and Structures, Pentech Press, London, 749-780.

12

Rankine, W.J.M., 1857, On the stability of loose earth, Philosophical Transactions of the Royal Society of London, 147, 9-27.

10.1098/rstl.1857.0003
13

Sato, M., Kuwano, R., 2015, Influence of location of subsurface structures on development of underground cavities induced by internal erosion, Soils and Foundations, 55, 829-840.

10.1016/j.sandf.2015.06.014
14

Shiau, J., Bishal, S.K., Keawsawasvong, S., 2022, Three-dimensional sinkhole stability of spherical cavity, Acta Geotechnica, 17, 3947-3958.

10.1007/s11440-022-01522-8
15

SMG (Seoul Metropolitan Government), 2016, Seoul-type cavity management classification standards, 15p (in Korean).

16

Wang, Y., Zhao, H., Deng, S., Li, D., 2020, Finite element simulation and multi-factor stress prediction model for cement concrete pavement considering void under slab, Materials, 13, 5294.

10.3390/ma1322529433238419PMC7700699
Information
  • Publisher :Korean Society of Engineering Geology
  • Publisher(Ko) :대한지질공학회
  • Journal Title :The Journal of Engineering Geology
  • Journal Title(Ko) :지질공학
  • Volume : 36
  • No :2
  • Pages :313-332
  • Received Date : 2026-06-04
  • Revised Date : 2026-06-24
  • Accepted Date : 2026-06-24
  • DOI :https://doi.org/10.9720/kseg.2026.2.313
Journal Informaiton The Journal of Engineering Geology The Journal of Engineering Geology
Online Submission
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • KCI 문헌 유사도 검사
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close