Prediction of End Bearing Capacity for Pre-Bored Steel Pipe Piles Using Instrumented Spt Rods

Moon S. Nam; Young-Ho Park; Yong-Seok Park

doi:10.7843/kgs.2013.29.12.105

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2013 Vol.29, Issue 12 Preview Page

Prediction of End Bearing Capacity for Pre-Bored Steel Pipe Piles Using Instrumented Spt Rods SPT 에너지효율 측정 롯드를 이용한 매입말뚝의 선단지지력 예측

31 December 2013. pp. 105-111

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Abstract

The standard penetration test (SPT) has been widely used because of its usability, economy, and many correlations with soil properties among other factors. In SPT, hammer energy is an important factor to evaluate and calibrate N values. To measure hammer energy, an instrumented SPT rod was developed considering that stress waves transferring on rods during SPT driving are the same as stress waves transferring on piles due to pile driving. Using this idea, an instrumented SPT rod with a pile driving analyzer was applied as a pile capacity prediction tool in this study. In order to evaluate this method, SPT and dynamic cone tests with the instrumented SPT rod were conducted and also 2 pile load tests were performed on pre-bored steel pipe piles at the same test site. End bearings were predicted by CAPWAP analysis on force and velocity waves from dynamic cone penetration tests and SPT. Comparing these predicted end bearings with static pile load tests, a new prediction method of the end bearing capacity using the instrumented SPT rod was proposed.

Keywords

SPT

Dynamic cone tests

Instrumented SPT rods

End bearing

Pre-bored steel pile piles

국내외에서 널리 사용 중인 표준관입시험(Standard Penetration Test, SPT)은 작업의 용이성, 다양한 지반정수와 강도정수를 결정방법 등의 장점을 지니고 있다. 이러한 SPT 수행시에 발생하는 해머 에너지는 N치의 산정 및 보정에 매우 중요한 영향인자가 된다. SPT시험시 해머 타격에 의하여 롯드로 응력파가 전달되는 현상이 말뚝 항타 시에 발생하는 현상과 동일하다하여 SPT에 PDA장비를 적용하여 관입에너지를 측정하는 방법이 개발되어 사용 중에 있다. 본 연구에서는 SPT 롯드를 말뚝으로 가정하여 SPT 에너지 효율 측정롯드를 SPT시험과 동적콘관입시험에 적용하여 얻어진 힘과 속도의 파형을 매칭기법(CAPWAP, CAse Pile Wave Analysis Program) 분석을 수행하여 매입말뚝에 대한 극한선단지지력을 예측하는 기법을 제안하였다. 또한, SPT 에너지 효율 측정롯드에서 예측된 선단지지력과 실물 말뚝정재하시험을 통하여 산정된 선단지지력을 비교분석하였다. 연구결과를 토대로 SPT나 동적콘관입시험을 통하여 매입말뚝의 지지력을 간편하게 예측할 수 있는 경험식을 제시하였다.

References

1.Alvarez, C., Zuckerman, B., and Lemke, J. (2006), “Dynamic Pile Analysis Using CAPWAP and Multiple Sensors”, GeoCongress 2006: Geotechnical Engineering in the Information Technology Age, ASCE, pp.1-5.

2.Lee, C. H. and Lee, W. J. (2005), “Ratio of Hammer Energy and Dynamic Efficiency of Standard Penetration Test”, Journal of Korean Geotechnical Society, Korean Geotechnical Society, Vol.21. No.9, pp.5-12.

3.Nam, M. S. (2006), “Design of IGM Socketed Drilled Shafts Using Texas Cone Penetrometer Tests”, Journal of Korean Geotechnical Society, Korean Geotechnical Society, Vol.22 No.10, pp.55-68.

4.Nam, M. S. and Vipulanandan, C. (2010), “Relationship between Texas Cone Penetrometer Tests and Axial Resistances of Drilled Shafts Socketed in Clay Shale and Limestone”, Journal of Geo-technical and Geoenvironmental Engineering, ASCE, Vol.136, No. 8, pp.1161-1165.

5.Park, Y. H., Kim, N. Y., Lee, B. J., Lee, K. H., Kim, I. H., and Park, Y. S. (2010), “Practiacl Application of Semi-Integral Abutment Bridge”, Report No. EXTRI-2011-12-534.9607, Expressway & Trans-portation Research Institute, Korea Expressway Corporation.

6.TxDOT (Texas Department of Transportation) (2000), “Geotechnical Manual (On-line Version)”, Texas Department of Transportation, Bridge Division, Austin, Texas.

Information

Publisher :The Korean Geotechnical Society
Publisher(Ko) :한국지반공학회
Journal Title :Journal of the Korean Geotechnical Society
Journal Title(Ko) :한국지반공학회 논문집
Volume : 29
No :12
Pages :105-111
Received Date : 2013-11-01
Revised Date : 2013-11-29
Accepted Date : 2013-12-03
DOI :https://doi.org/10.7843/kgs.2013.29.12.105

Journal of the Korean Geotechnical Society ISSN:1229-2427(Print) 2288-646X(Online) 한국지반공학회 논문집

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