All Issue

2025 Vol.24, Issue 1 Preview Page

Research Article

Numerical Analysis of Settlement Behavior of Caisson-Type Breakwaters and Ground Improvement Effects Considering Excess Pore Water Pressure Dissipation

과잉간극수압 소산에 따른 케이슨식 방파제의 침하 및 지반 개량 효과에 대한 수치해석적 연구

Hyeonsu Yun1
,
Seong-Kyu Yun2
,
Sanghyeon Choi3
,
Gichun Kang4*
윤 현수1
,
윤 성규2
,
최 상현3
,
강 기천4*
1Member, Ph.D. Canditate, Department of Civil Engineering, Gyeongsang National University, 501 Jinjudae-Ro, Jinju 52828, Republic of Korea
2Member, Research Professor, Engineering Research Institute, Gyeongsang National University, 501 Jinjudae-Ro, Jinju 52828, Republic of Korea
3Non-Member, Graduate Student, Department of Civil Engineering, Gyeongsang National University, 501 Jinjudae-Ro, Jinju 52828, Republic of Korea
4Member, Associate Professor, Department of Civil Engineering, Gyeongsang National University, 501 Jinjudae-Ro, Jinju 52828, Republic of Korea
*Corresponding Author
30 March 2025. pp. 113-120
PDF XML Citation
Abstract

Earthquakes are a major factor affecting the stability of marine structures, and liquefaction occurs in saturated sandy soils, causing damage such as settlement, tilting, and collapse of structures. The 2017 Pohang earthquake was the first case of liquefaction in South Korea, resulting in damages at Yeongilman Port, including caisson settlement (approximately 10cm), hinterland settlement (10–20cm), and horizontal displacement (less than 15cm). In seismic response analysis, undrained conditions are typically assumed; however, this approach has limitations as it fails to account for additional displacements occurring after the dissipation of excess pore water pressure. To address this issue, an analysis considering drained conditions is necessary. Therefore, this study investigates the liquefaction-induced damage under drained conditions considering the dissipation of excess pore water pressure and explores methods to mitigate damage through ground improvement. As a result, the stability of the caisson breakwater was secured by improving the sandy ground beneath the caisson.

Keywords
Earthquake
Liquefaction
Caisson breakwater

지진은 해양 구조물 안정성에 큰 영향을 미치는 요인으로, 액상화는 포화된 사질토 지반에서 발생하여 구조물의 침하, 기울어짐, 붕괴 등과 같은 피해를 발생시킨다. 2017년 포항지진으로 인해 국내 최초로 액상화 현상이 발생하였으며, 영일만항에서 케이슨의 침하(약 10cm), 배후지 침하(10~20cm), 수평변위(15cm 이하) 등의 피해가 발생하였다. 또한 지진 응답해석의 경우 주로 비배수조건으로 수행하지만, 과잉간극수압 소산 후 추가 변위를 반영하지 못하는 한계를 가지고 있다. 이를 해결하기 위해 배수조건을 고려한 해석이 필요하다. 이에 따라 본 연구는 배수조건시 과잉간극수압 소산에 따른 액상화 피해에 대해 규명하며, 지반개량으로 인한 피해 저감 방법에 대해 연구를 수행하였다. 결과적으로 케이슨 하부의 모래지반에 개량을 통해 케이슨 방파제의 안정성을 확보하였다.

References
1

Iai, S., Matsunaga, Y. and Kameoka, T. (1992a), "Strain space plasticity model for cyclic mobility", Soils and Foundations, Vol.32, No.2, pp.1-15.

10.3208/sandf1972.32.2_1
2

Iai, S., Matsunaga, Y. and Kameoka, T. (1992b), "Analysis of undrained cyclic behavior of sand under anisotropic consolidation", Soils and Foundations, Vol.32, No.2, pp.16-20.

10.3208/sandf1972.32.2_16
3

Iai, S., Tobita, T., Ozutsumi, O. and Ueda, K. (2011), "Dilatancy of Granular Materials in a Strain Space Multiple Mechanism Model", International Journal for Numerical and Analytical Methods in Geomechanics, Vol.35, No.3, pp.360-392.

10.1002/nag.899
4

Iai, S., Ueda, K., Tobita, T. and Ozutsumi, O. (2013), "Finite Strain Formulation of a Strain Space Multiple Mechanism Model for Granular Materials", International Journal for Numerical and Analytical Methods in Geomechanics, Vol.37, No.9, pp.1189-1212.

10.1002/nag.2084
5

Kang, G. C. (2011), "Behavior of Buried Geo-structures due to Increase of Excess Pore Water Pressure Ratio During Earthquakes", Journal of the Korean Society of Geotechnical Engineering, Vol.12, No.27, pp.27-28.

10.7843/kgs.2011.27.12.027
6

Kim, S, J., Hwang, W, K., Kim, T. H. and Kang, G. C. (2019), "A Case Study on Earthquake-induced Deformation of Quay Wall and Backfill in Pohang by 2D-Effective Stress Analysis", Journal of the Korean Society of Geotechnical Engineering, Vol.35, No.7, pp.15-27.

7

Mun, G. Y. (2018), A study on the effect of relative density and particle size distribution on the liquefaction resistancestrength of sand in pohang liquefaction region. Master's thesis, Pusan National University.

8

Park, S. S., Nong, Z., Choi, S. G. and Moon, H. D. (2018a), "Resistance of Pohang Sand", Journal of the Korean Geotechnical Society, Vol.34, No.9, pp.5-17.

9

Park, S. S., Nong, Z., Choi, S. G. and Moon, H. D. (2018b), "Liquefaction resistance of pohang sand", Journal of the Korean Geotechnical Society, Vol.34, No.9, pp.5-17.

10

Towhata, I. and Ishihara, K. (1985), "Shear Work and Pore Water Pressure in Undrained Shear", Soils and Foundations, Vol.25, No.3, pp.73-84

10.3208/sandf1972.25.3_73
Information
  • Publisher :Korean Geosythetics Society
  • Publisher(Ko) :한국지반신소재학회
  • Journal Title :Journal of the Korean Geosynthetics Society
  • Journal Title(Ko) :한국지반신소재학회 논문집
  • Volume : 24
  • No :1
  • Pages :113-120
  • Received Date : 2025-02-19
  • Revised Date : 2025-03-24
  • Accepted Date : 2025-03-25
  • DOI :https://doi.org/10.12814/jkgss.2025.24.1.113
Journal Informaiton Journal of the Korean Geosynthetics Society Journal of the Korean Geosynthetics Society
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close