Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Mechanism on Bulb Formation of Compaction Pile Depending on Materials

재료에 따른 다짐말뚝 구근 형성 메커니즘

  • 최정호 (공주대학교 건설환경공학과) ;
  • 이민지 (공주대학교 건설환경공학과) ;
  • ;
  • 박성진 (공주대학교 사회환경공학과) ;
  • 추연욱 (공주대학교 사회환경공학과) ;
  • 김일곤 ((주)초석건설산업) ;
  • 김병규 ((주)한국항만기술단 기술연구소)
  • Received : 2022.03.22
  • Accepted : 2022.06.13
  • Published : 2022.07.31
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Abstract

In this paper, a small-scale model testing system was developed using a series of small-scale model tests to analyze the mechanism of compaction pile formation and evaluate the quality of controlled grading aggregates proposed as an alternative material to the sand compaction pile (SCP) method and granular compaction pile (GCP). These are the most typical ground improvement methods in field practice, particularly for soft grounds. However, the SCP has faced difficulties due to the supply shortage of natural sand and the corresponding price surge of sand. The GCP is limited in marine soft grounds because of the failure occurring at the pile tip caused by excessive expansion of the deeper bulbs, leading to uneven bulb formation. The uniformity of compacted pile bulbs is critical to ensuring the bearing capacity and quality of the compaction pile. This study aims to evaluate the performance of the new material and controlled grading aggregates using small-scale model tests simulating field compaction process to investigate its potential application in comparison with SCP. The compaction piles are examined in four cases according to different materials used for compaction pile and clay strength. The compaction pile materials, which are made of sand and controlled grading aggregates, used in this study were compared to reveal the mechanism of the bulb creation. The experimental data confirm that the bulb formation quality of the traditional sand and the new material, controlled grading aggregates are comparable. The compaction pile made of controlled grading aggregates presents higher bearing capacity than that of marine sand.

본 논문에서는 연약지반개량을 위해 활용되고 있는 모래다짐말뚝 공법의 개선을 위해 개발된 입도조정골재 다짐말뚝의 구근 형성 및 품질을 평가하고자 다짐말뚝 시공을 모사하는 축소모형실험 시스템을 개발하고 일련의 실험을 수행하였다. 현재 모래다짐말뚝 공법의 경우 모래의 공급 부족으로 인해 경제성이 하락하였고, 쇄석다짐말뚝 공법은 해상 초연약점토지반에 시공 시 구근의 팽창 파괴로 인한 불균일한 구근과 퍼짐 현상 발생으로 해상 연약지반 적용에 한계가 있어왔다. 구근의 균일한 형성은 다짐말뚝의 지지력에 큰 영향을 미치나, 현재까지 구근 형성에 대한 연구사례는 전무하다. 따라서, 본 연구에서는 다짐말뚝 구근이 시공되는 절차를 모사하여 구근 형성 메커니즘을 규명하고, 기존 다짐말뚝 공법을 개선하는 입도조정골재의 품질 평가를 목표로 하였다. 본 연구에서는 다짐말뚝 재료와 지반 강도를 매개변수로 하여 4차례 실험을 수행하였다. 다짐말뚝 재료는 입도조정골재와 모래를 비교·분석하였다. 실험결과, 입도조정골재 다짐말뚝의 구근은 모래다짐말뚝과 유사한 품질로 나타났으며, 입도조정골재 다짐말뚝의 지지력이 모래다짐말뚝 보다 향상되는 것을 확인하였다.

Keywords

Acknowledgement

본 연구는 초석건설산업(주)과 은성O&C의 연구비지원과 행정안전부의 방재안전분야 전문인력 양성사업 지원을 받았으며, 이에 깊은 감사를 드립니다.

References

  1. Barksdale, R. D. and Bachus, R. C. (1983), "Design and Construction of Stone Columns", Vol. 1, Report No. FHWA/RD-83/ 026, National Technical Information Service, Federal Highway Administration, Springfield, Virginia, pp.195.
  2. Basack, S., Siahaan, F., Indraratna, B., and Rujikiatkamjorn, C. (2018), "Stone Column-Stabilized Soft-Soil Performance Influenced by Clogging and Lateral Deformation: Laboratory and Numerical Evaluation", International Journal of Geomechanics, Vol.18, No.6, 04018058. https://doi.org/10.1061/(asce)gm.1943-5622.0001148
  3. Bong, T. H. and Kim, B. I. (2017), "Prediction of Ultimate Bearing Capacity of Soft Soils Reinforced by Gravel Compaction Pile Using Multiple Regression Analysis and Artificial Neural Network", Journal of Korean Geotechnical Society, Vol.33, No.6, pp.27-36. https://doi.org/10.7843/KGS.2017.33.6.27
  4. Bong, T. H., Kim, B. I., and Han, J. T. (2018), "Estimation of Ultimate Bearing Capacity of SCP and GCP Reinf orced Clay f or Laboratory Load Test Data", Journal of the Korean Geotechnical Society, Vol.34, No.6, pp.37-47. https://doi.org/10.7843/KGS.2018.34.6.37
  5. Brauns, J. (1978), "Initial Bearing Capacity of Stone Columns and Sand Piles", In Int. Symp. on Soil Reinforcing and Stabilizing Techniques in Engineering Practice, Vol.1, pp.497-512.
  6. Choi, Y. K., Kim, W. C., Jung, C. K., Lee, M. H., and Kim, T. H. (2002), "A State of the Art for the Vibrated Crushed-stone Compaction Pile", Journal of the Korean Geo-Environmental Society, Vol.3, No.3, pp.65-77.
  7. Chu, I. C. (2013), "An Experimental Study on the Optimum Mixing Ratio of Sand-mixed Granular Compaction Pile", M. S. Dissertation, Hanyang University, Seoul, Korea.
  8. Chun, B. S., Kim, W. C., and Jo, Y. W. (2004), "Comparative Study on the Prediction Method of Bearing Capacity for Single Stone Column", Journal of the Korean Geo-Environmental Society, Vol.5, No.1, pp.55-64.
  9. Do, J. N. (2012), "Compression Characteristics of Bottom Ash Mixture Compaction Pile", Ph. D. Dissertation, Hanyang University, Seoul, Korea.
  10. Fattah, M. Y., Al-Neami, M. A., and Al-Suhaily, A. S. (2017), "Estimation of Bearing Capacity of Floating Group of Stone Columns", Engineering Science and Technology, an International Journal, Vol.20, pp.1166-1172. https://doi.org/10.1016/j.jestch.2017.03.005
  11. Gibson, R.E. and Anderson, W.F. (1961), "In Situ Measurement of Soil Properties with the Pressuremeter", Civil Engineering and Public Works Review, Vol.56, No.658, pp.615-620.
  12. Greenwood, D. A. (1970), "Mechanical Improvement of Soils Below Ground Surface", Proceeding of Ground Engineering Conference, Institute of Civil Engineering, pp.11-22.
  13. Hughes, J. M. O. and Withers, N. J. (1974), "Reinforcing Soft Cohesive Soil with Stone Columns", Ground Engineering, Vol.7, pp.42-49.
  14. Kang, Y. and Kim, H. T. (2004), "Analysis of Bearing Capacity Characteristics on Granular Compaction Pile - Focusing on the Model Test Results", Journal of the Korean Geo-Environmental Society, Vol.5, No.2, pp.51-62.
  15. Kim, B. I., Lee, S. W., Kim, B. S., and Lyu, W. K. (2004), "Comparison of Bearing Capacity between SCP and GCP by Unit Cell Model Tests", Journal of the Korean Geotechnical Society, Vol.20, No.8, pp.41-48.
  16. Kim, I. G., Chosuk construction co., Korea port engineering co. Sekwang Engineering Consultants Co. and Eunsung onshore/offshore Marine & Construction Co. (2021), "Marine soft ground improvement method using ball-type casing, automatic air control device and aggregate for mechanical stabilization", Korea Patent No. 10-2288513-0000.
  17. Kim, J. H. (2009), "The Experimental Study on Composite Ground Behavior and Aspect of Clay Gone through Compaction Pile of Recycled Aggregate Compaction Piles", M. S. Dissertation, Hongik University, Seoul, Korea
  18. Kim, M. S. (2016), "The behavior of soft ground reinforced with granular compaction pile", M. S. Dissertation, Chosun University, Gwangju, Korea.
  19. Korea Ocean Research & Development Institute (KORDI) (2001), "Design and construction guidelines for sand compaction piles and stone columns", Ministry of Oceans and Fisheries (MOF).
  20. Lee, D. Y., Kang, H. N., and Chun, B. S. (2010), "Characteristics on Shear Strength and Clogging Phenomenon of Bottom Ash and Rammed Aggregate Mixture Compaction Pile", Journal of the Korean Geo-Environmental Society, Vol.11, No.3, pp.33-41.
  21. Madhav, M. R. and Vitkar, R. P. (1978), "Strip Footing on Weak Clay Stabilized with Granular Trench of Pile", Canadian Geotechnical Journal, Vol.15, No.4, pp.605-609. https://doi.org/10.1139/t78-066
  22. Park, M. C., Kwon, H. C., Shin H. H., Jang, G. S., and Lee, S. (2011), "An Analysis of the Composite Discharge Capacity Effect with GCP Method", Journal of the Korean Geo-Environmental Society, Vol.12, No.12, pp.37-46.
  23. You, S. K. and Kin, J. H. (2009), "Experimental Study of Clays Mixed into Compaction Piles", Journal of the Korean Geosynthetics Society, Vol.8, No.4, pp.41-46.