American Society of Civil Engineers

Estimation of Axial Load Capacity for Bored Tapered Piles Using CPT Results in Sand

by Junhwan Lee, (corresponding author), (Associate Professor, School of Civil and Environmental Engineering, Yonsei Univ., Seoul 120-749, Korea E-mail:, Kyuho Paik, (Professor, Dept. of Civil Engineering, Kwandong Univ., Gangnung 210-701, Korea.), Deahong Kim, (Senior Researcher, Korea Electric Power Corporation (KEPCO), Daejeon 305-380, Korea.), and Sungwuk Hwang, (Formerly, Graduate Research Assistant, School of Civil and Environmental Engineering, Yonsei Univ., Seoul 120-749, Korea.)

Journal of Geotechnical and Geoenvironmental Engineering, Vol. 135, No. 9, September 2009, pp. 1285-1294, (doi:

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Document type: Journal Paper
Abstract: Tapered piles in comparison to cylindrical piles can be beneficial in terms of the load capacity. In this paper, estimation of the load capacity for tapered piles using cone penetration test (CPT) resistance was investigated. Fourteen calibration chamber load tests using different pile types and six CPTs were conducted under various soil conditions. From the calibration chamber test results, the total, base, and shaft load capacities were analyzed in terms of soil conditions and taper angle. To evaluate CPT-based load capacity of tapered piles, normalized base and shaft resistances were obtained from normalized unit load-settlement curves. Based on the normalized base and shaft resistances, design equations that can be used to evaluate the base and shaft resistances of tapered piles were proposed. The proposed method is valid for sands of medium to dense conditions, while it may result in unconservative predictions for loose sands. To check the accuracy of the proposed method, field load tests using both cylindrical and tapered piles were conducted and compared with the predictions using the proposed method. A simplified approach using an equivalent cylindrical pile was also investigated and compared.

ASCE Subject Headings:
Load bearing capacity
Cone penetration tests
Sand (soil type)
Axial loads