Development of Steel Pipe Attached PHC Piles for Increasing Base Load Capacity of Bored Pre-cast Piles

Kyu-Ho Paik; Hee-Jeong Yang

doi:10.7843/kgs.2013.29.8.53

All Issue

2013 Vol.29, Issue 8 Preview Page Next Page

Development of Steel Pipe Attached PHC Piles for Increasing Base Load Capacity of Bored Pre-cast Piles 매입말뚝의 선단지지력 증대를 위한 강관 부착 PHC파일 개발

31 August 2013. pp. 53-63

PDF XML

Abstract

Bored pre-cast piles using PHC piles is widely used in foundation of building structures constructed in urban areas because noise and vibration due to pile installation are low. However, since slime is formed at the base of borehole and the density of bearing stratum surrounding the base of borehole is decreased due to stress relaxation in drilling process of bored pre-cast pile method, the base load capacity of bored pre-cast piles is very low compared to the strength of bearing stratum. In this study, a new type of PHC pile, which short steel pipe with the same diameter as the PHC pile is attached to the pile tip, is developed to increase the base load capacity of bored pre-cast piles. In order to check the effect of the use of new PHC pile on the base load capacity of bored pre-cast piles, field pile load tests are performed for bored pre-cast piles using the new and existing PHC piles. Results of the pile load tests show that the new PHC pile gives higher base load capacity to bored pre-cast piles than the existing PHC pile, since the tip of new PHC pile is penetrated to undisturbed bearing stratum passing through the slime at the base of borehole and the loosened bearing stratum under the slime by pile driving using light hammer.

Keywords

New PHC pile

Bored pre-cast pile

Base load capacity

Field pile load test

PHC파일을 사용한 매입말뚝은 시공 중에 발생하는 소음과 진동을 최소화할 수 있다는 장점 때문에 많은 경우 도심지에 건설되는 건축구조물의 기초로 사용된다. 그러나 매입말뚝의 시공을 위해 굴착공을 천공하는 과정에서 굴착공 저면에 슬라임이 형성되고 그 하부의 지반은 응력이완으로 인해 조밀도가 느슨해져서 매입말뚝은 원지반의 강도에 비해 선단지지력이 작게 발휘된다는 단점을 갖고 있다. 본 연구에서는 매입말뚝의 선단지지력을 증대시키기 위해 PHC파일의 선단에 길이가 짧고 PHC파일과 직경이 동일한 강관을 부착한 새로운 형태의 PHC파일을 개발하였다. 새로운 PHC파일을 사용한 매입말뚝의 선단지지력 증대 효과를 검증하기 위해 현장 말뚝재하시험을 수행한 결과 새로운 PHC파일은 경타에 의해 파일 선단이 굴착공 저면의 슬라임과 그 하부의 이완된 지지층 영역을 관통해서 강도가 큰 원지반에 관입됨으로써 기존 PHC파일보다 매입말뚝의 선단지지력을 상당히 증대시키는 것으로 나타났다.

References

1.Carranza-Torres, C. and Fairhurst, C. (1999), “The Elasto-Plastic Response of Underground Excavations in Rock Masses that Satisfy the Hoek-Brown Failure Criterion”, International Journal of Rock Mechanics and Mining Sciences, Vol.36, pp.777-809.

2.CEN (Comité Européen De Normalisation) (2004), EN 1997 Eurocode 7, Geotechnical - Part 1: General Rules, CEN.

3.Davisson, M. T. (1972), “High Capacity Piles”, Proceeding of Lecture Series on Innovations in Foundation Construction, ASCE, Illinois Section, Chicago, pp.81-112.

4.Jardine, F. M. (1988), “Introduction to Papers 1-9”, Proceedings of Penetration Testing in the UK, ICE, Birmingham, pp.23-49.

5.KGS (Korean Geotechnical Society) (2008), Structural Foundation Design Manual.

6.Lee, J. H., Salgado, R., and Paik, K. H. (2003), “Estimation of Load Capacity of Pipe Piles in Sand Based on CPT Results”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.129, No.5, pp.391-403.

7.Paik, K. H. and Lee, S. R. (1993), “Behavior of Soil Plugs in Open-Ended Model Piles Driven into Sands”, Marine Georesources and Geotechnology, Vol.11, pp.353-373.

8.Paik, K. H. and Salgado, R. (2003), “Determination of Bearing Capacity of Open-Ended Piles in Sand”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.129, No.1, pp.46-57.

9.Yoo, C., Kim, S., Heo, K., and Song, K. (2007), “End Bearing Capacity of Pile Tip-enlarged PHC Piles in Weathered Rock”, Journal of Korean Geotechnical Society, Vol.23, No.1, pp.23-37.

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 :8
Pages :53-63
Received Date : 2013-03-03
Revised Date : 2013-06-14
Accepted Date : 2013-07-11
DOI :https://doi.org/10.7843/kgs.2013.29.8.53

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

All Issue