Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
권호 표지
DOI QR코드

DOI QR Code

Effect of Ground Confine Pressure on Pullout Resistance of Piles Using Model Experiment

말뚝의 인발저항에 대한 지중 구속압 영향 분석을 위한 실내모형실험

  • Received : 2023.12.03
  • Accepted : 2023.12.15
  • Published : 2023.12.30
Download PDF
⟨ Previous Next ⟩

Abstract

This paper describes the results of a pile pullout test considering the confine pressure and fines content of the ground. The Pullout tests were conducted under various ground conditions using model piles. The effect of ground confine pressure on the pullout resistance and the pullout resistance parameters of the pile were evaluated based on the experimental results. The results of pullout test showed that the maximum pullout resistance occurred at a pullout displacement of about 7mm to 9mm, regardless of the fines content and the confine pressure of the ground. The maximum pullout resistance of the pile decreased as the fines content of the ground increased, and this trend became clearer as the confine pressure increased. The pullout resistance calculated by theoretical formula was compared with the experimental results in order to ensure the reliability of the pullout test results. The comparative results showed that the experimental and theoretical values showed a tendency to decrease the pullout resistance as the fines content increased, in all confine pressure conditions. The analysis result of the pullout resistance parameters confirmed that the pullout resistance was greatly influenced by the adhesion compared to the interface friction angle, as the fines content of the ground around the pile increased.

본 연구에서는 말뚝에 작용하는 구속압과 지반의 세립분 함유율을 고려한 말뚝 인발실험을 실시하였다. 그리고 실험 결과를 이용하여 말뚝의 인발저항에 미치는 지중 구속압의 영향을 분석하여 인발저항정수를 고찰하였다. 인발실험 결과, 모형지반의 세립분 함유율과 구속압의 크기에 관계없이 약 7mm~9mm의 인발변위에서 최대인발저항력이 발생되었다. 말뚝의 최대인발저항력은 모형지반의 세립분 함유율이 증가할수록 감소하였고, 이러한 경향은 구속압이 클수록 현격하게 나타났다. 말뚝인발실험 결과의 신뢰성을 검토하기 위해 인발저항력을 이론식으로 산정해 실험결과와 비교한 결과, 모든 구속압 조건에서 세립분 함유율 증가에 따라 실험값과 이론값 모두 동일하게 인발저항력이 감소하는 경향을 보였다. 인발저항정수에 대한 분석 결과, 말뚝과 지반의 경계에서 발생하는 인발저항력에 있어서 주변 지반의 세립분 함유율이 증가할수록 경계면 마찰각보다 부착력의 영향이 커지는 것을 확인하였다.

Keywords

Acknowledgement

This work has been supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No.2021R1F1A1052445).

References

  1. Abi, E., Shen, L., Liu, M., Du, H., Shu, D. and Han, Y. (2023), "Calculation Model of Vertical Bearing Capacity of Rock-Embedded Piles Based on the Softening of Pile Side Friction Resistance", Journal of Marine Science and Engineering, Vol.11, No.5, p.939. 
  2. Ashour, M. and Abbas, A. (2020), "Response of piles in multi-layers of soil under uplift forces", International Journal of Geomechanics, Vol.20, No.6, 04020056. 
  3. Chen, C., Yang, Q., Leng, W., Dong, J., Xu, F., Wei, L. and Ruan, B. (2022), "Experimental Investigation of the Mechanical Properties of the Sand-Concrete Pile Interface Considering Roughness and Relative Density", Materials, Vol.15, No.13, p.4480. 
  4. Emirler, B., Tolun, M. and Yildiz, A. (2019), "An experimental study of rough single pile and pile group under uplift loading in sand", European Journal of Environmental and Civil Engineering, Vol.25, No.3, pp.557-574.  https://doi.org/10.1080/19648189.2019.1642242
  5. Khatri, V. N. and Kumar, J. (2011), "Uplift Capacity of Axially Loaded Piles in Clays", International Journal of Geomechanics, Vol.11, No.1, pp.23-28.  https://doi.org/10.1061/(ASCE)GM.1943-5622.0000064
  6. Korean Geotechnical Society (2018), "구조물기초설계기준 해설", pp.293-297. (in Korean) 
  7. Lim, Y. J. and Seo, S. H. (2002), "Uplift Testing and Load-transfer Characteristics of Model Drilled Shafts in Compacted Weathered Granite Soils", Journal of the Korean Geotechnical Society, Vol.18, No.4, pp.105-117. (in Korean with English summary) 
  8. Ma, H., Ma, Y., Zhu, L. and Zhang, H. (2023), "Experimental Study on the Difference Mechanism of Shaft Resistance between Uplift Piles and Compressive Piles", Applied Sciences, Vol.13, No.5, p.3158. 
  9. Meyerhof, G. G. (1976), "Bearing Capacity and Settlement of Pile Foundations", Journal of Geotechnical Engineering, ASCE, Vol.102, No.GT-3, pp.197-228.  https://doi.org/10.1061/AJGEB6.0000243
  10. Meyerhof, G. G. and Adams, J. I. (1968), "The Ultimate Uplift Capacity of Foundation", Journal of Canadian Geotechnical, Vol.5, No.4, pp.225-244.  https://doi.org/10.1139/t68-024
  11. O'Neill, M. W. and Reese, L. C. (1999), "Drilled Shafts: Construction Procedures and Design Methods", Publication No. FHWA-IF-99-025, Federal Highway Administration. 
  12. Park, K., Kim, D., Kim, G. and Lee, W. (2021), "Evaluation of the Pullout Behavior of Pre-Bored Piles Embedded in Rock", Materials, Vol.14, No.19, p.5593. 
  13. Wang, G., Hong, B., Liu, X., Sun, D., Shao, Z. and Yao, Y. (2023), "Experimental Study on the Shear Properties of Soil around Piles with Permeation Grouting", Applied Sciences, Vol.13, No.1, p.621. 
  14. You, S. K. and Hong. G. (2022), "Analysis of Shear Resistance Characteristics in Pile-Soil Interface using Large-Scale Direct Shear Test", Journal of the Korean Geosynthetics Society, Vol.21, No.3, pp.61-69. (in Korean with English summary)  https://doi.org/10.12814/JKGSS.2022.21.3.061
  15. You, S. K., Hong, G., Jeong, M., Shin, H., Lee, K. W. and Ryu, J. (2018), "Effect of Relative Density and Fines Content on Pullout Resistance Performance of Drilled Shafts", Journal of the Korean Geotechnical Society, Vol.34, No.4, pp.37-47. (in Korean with English summary)  https://doi.org/10.7843/KGS.2018.34.4.37
  16. You, S. K., Shin, H., Lee, K. W., Park, J., Choi, C. L. and Hong. G. (2019a), "Evaluation on Applicability of Finite Element Analysis in Model Test of Pile Pullout", Journal of the Korean Geosynthetics Society, Vol.18, No.2, pp.11-21. (in Korean with English summary) 
  17. You, S. K., Shin, H., Lee, K. W., Park, J., Choi, C. L. and Hong. G. (2019b), "A Study on Strength Reduction Factor of Pile-soil Interface for Evaluation of Pile Pullout Resistance by Soil Condition", Journal of the Korean Geosynthetics Society, Vol.18, No.2, pp.45-54. (in Korean with English summary)