DOI QR코드

DOI QR Code

A Study of Correlation between SPT N-value and Exerted Electrical Energy Required for Ground Drilling I : Basic Study (Laboratory Soil Box Test)

지반굴착에 소요되는 전기에너지와 표준관입시험 N값과의 상관관계 연구 I : 기초연구(실내토조실험)

  • Choi, Changho (Dept. of Geotechnical Engineering, Korea Institute of Construction Technology)
  • Received : 2012.12.04
  • Accepted : 2012.12.24
  • Published : 2012.12.30

Abstract

Ground drilling is a common method to conduct site investigation, soil improvement, and pile installation. In the point of construction ground drilling requires electrical energy to drill a hole in ground in which the energy exerts into the motor located on the head of auger and generates rotational power. In this paper it is verified that the exerted electrical energy is closely related to the strength characteristics of ground. Measurement sensors, recording system, and drilling system were developed to obtain exerted motor current and drilling depth and laboratory soil box tests were carried out. The measured motor current and boring depth were applied to predict SPT N-value and the prediction results were compared to SPT N-value of laboratory tests. The test results show that the exerted electrical energy to bore ground be a good index to estimate SPT N-value.

지반굴착은 지반조사, 연약지반 개량, 선굴착 말뚝 시공 등 지반공학 분야에서 널리 사용되고 있다. 지반을 굴착하기 위해서는 오거의 상부에 설치된 구동모터를 회전시키는 전기에너지가 필요하게 된다. 본 논문에서는 지반굴착시 구동모터에 소요되는 전기에너지와 지반의 표준관입시험 N값의 상관관계를 분석하고자 하였다. 이를 위하여 지반굴착시 변화하는 전류값과 굴착깊이를 계측하기 위한 측정센서, 데이터 저장시스템, 굴착시스템 등의 실내실험 장치를 개발하였으며, 모형토조 실험을 수행하였다. 계측된 전류값과 굴착깊이는 표준관입시험 N값 추정에 이용되었으며 추정된 표준관입시험 N값은 실내실험으로부터 실측된 N값과 비교하였다. 비교결과 지반굴착에 소요되는 전기에너지를 이용하여 표준관입시험 N값을 추정할 수 있음을 확인하였다.

Keywords

References

  1. Bowles, J. E. (1996), Foundation Analysis and Design, 5th Ed., McGraw-Hill, pp.154-162.
  2. Chai, S.-G. (2000), "Q&A: Characteristics and application of prebored pile method", Geotechnical Engineering, Korean Geotechnical Society, Vol.16, No.7, pp.83-88.
  3. Choi, C., Cho, J., Chung, H., Lee, Y. (2007a), "SPT N-value Estimation from Exerted Electrical Motor Energy for Preboring Pile Installation," Proceedings of 7th Japnanese-Korean-French Seminar on Geo-Environmental Engineering, Grenoble, France, pp.293-298.
  4. Choi, C., Cho, J., Lee, Y., Chung, H.-I., Park, Y.-B. (2007b), "A Study for Predicting Rotational Curtting Torque from Electrical Energy Required for Ground Drilling", Journal of Korean Geotechnical Society, Vol.23, No.7, pp.1-8.
  5. Fang, H.-Y. (1991), Foundation Engineering Handbook, Van Nostrand Reinhood, New York, pp.123-456.
  6. Geotechnical Engineering Research Group (2003), Plan, design, and construction of pile foundation in practice, Gunsul-JeongBo, pp.456-463.
  7. Korea Nation Housing Cooperation (2004), Solutions of Structural Problems for Engineers, pp.40-48. (in Korean)
  8. Lee, M. W. and Yi, C. T. (1989), Improvement of design and construction quality dontrol of pile foundation, Korea Institute of construction Technology, Research report, pp.123-456.
  9. Lee, W. J. (2000), Measurement of pile load transfer using fiber-optic sensor and characteristics of bored precast pile bearing capacity, Ph. D. Thesis, Dept. of Civil and Envoronmental Engr., Korea University.
  10. NI (2012), National Instrument web site, www.ni.com.
  11. Oh, Y. T., Kwon, W. T. and Chu, C. N. (2001a), "Cutting Torque Control in Drilling Part 1 : Design of a Cutting Torque Controller", Journal of the Korean Society of Precision Engineering, Vol.18, No.8, pp.96-106.
  12. Oh, Y. T., Kim, G. D. and Chu, C. N. (2001a), "Cutting Torque Control in Drilling Part 2 : Drilling Torque Control Using Spindle Motor Current and Its Effect on Drill Flank Wear", Journal of the Korean Society of Precision Engineering, Vol.18, No.8, pp.107-115.
  13. Park, Y.-H., Kim, N.-Y. and Yook, J.-H. (2004), Design and Construction of SIP Method(II), Korea Expressway Corporation Research Report, pp.35-39.
  14. Park, J.-B. (2000), Bearing Capacity of Displacement in-situ Concrete Pile, Ph. D. Thesis, Dept. of Civil Engr., Hanyang University.
  15. Perko, H. A. (2000), "Energy Method for Predicting the Installation Torque of Helical Foundations and Anchors", New Technological and Design Developments in Deep Foundations, ASCE, Geotechnical Special Publication No.100, pp.123-456.