Evaluation of Full-Sized Cast-in-Place Pile Capacity with Artificial Defects

Abstract

Cast-in-place piles in the field are likely to have unintended defects during construction, such as soft bottom, segregation of concrete, and contraction or enlargement of the cross section. The effect of defects in cast-in-place piles on the pile's resistant behavior was evaluated. Four piles with artificial defects of soft bottom, concrete segregation, and contractions of the cross section by 10% and 20%, respectively, as well as one sound pile, were constructed simultaneously. Static load tests, load transfer measurements, and integrity tests were performed for the piles. In addition, three-dimensional numerical analysis was conducted to analyze the effect of the contraction defect on the pile's resistant behavior. For the pile with the defect of concrete segregation, integrity tests and load transfer measurements showed that the pile strength was reduced by more than 50% in the section of the weak zone having the defects. For the piles that contained the defect of asymmetric contraction of the cross section, the measured strain in the defective section was lower than that in the section without the defect, and three-dimensional numerical analysis showed that the defect increased the axial stress in the section of the defect. Crosshole sonic loggings were conducted before and after static load tests. The difference in the loggings between the prestatic and poststatic load tests indicated the growth of defects as the piles were loaded.

Get full access to this article

View all access options for this article.

References

Chernauskas

L. R.

Defect Detection and Examination of Large Drilled Shafts Using a New Cross-Hole Sonic Logging System. In Performance Confirmation of Constructed Geotechnical Facilities, Proceedings of Sessions of ASCE Specialty Conference, Amherst, Mass., 2000, pp. 66–83.

Briaud

J.-L.

Defect and Length Predictions by NDT Methods for Nine Bored Piles. In Deep Foundations 2002: An International Perspective on Theory, Design, Construction, and Performance. Geotechnical Special Publication 116, 2002, pp. 173–192.

Baker

C. N.

, Parikh

, Briaud

J. L.

, Drumright

E. E.

, and Mensah

. Drilled Shafts. Publication FHWA-RD-92-004. FHWA, U.S. Department of Transportation, 1993.

Hoek

, and Bray

J. W.

. Rock Slope Engineering. Institution of Mining and Metallurgy, London, 1981.

Duncan

C. W.

Foundations on Rock. Chapman & Hall, London, 1992.

Das

B. M.

Principles of Foundation Engineering, 2nd ed. PWS-KENT, Boston, Mass., 1990, p. 528.

Chan

S. F.

An Experimental Study of Behavior of End Bearing Cast-in-Situ Piles. Proc., 4th Southeast Asia Conference on Soil Engineering, Kuala Lumpur, Malaysia, 1975.

Balakrishnan

E. G.

, Balasubramaniam

A. S.

, and Phien-wej

. Load Deformation Analysis of Bored Piles in Residual Weathered Formation. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 125, No. 2, 1999, pp. 122–131.

Holtz

R. D.

Capacity Analysis of Drilled Shafts with Defects. In Deep Foundations 2002: An International Perspective on Theory, Design, Construction, and Performance. Geotechnical Special Publication 116, 2002, pp. 1120–1135.

10.

Cundall

P. A.

Explicit Finite Difference Methods in Geomechanics. In Numerical Methods in Engineering, Proceedings of the EF Conference on Numerical Methods in Geomechanics, Vol. 1 ( Desai

C. S.

, ed.). Blacksburg, Va., 1976, pp. 132–150.

11.

Osterberg

J. O.

, and Gill

S. A.

. Load Transfer Mechanism for Piers Socketed in Hard Soils or Rock. Proc., 9th Canadian Rock Mechanics Symposium, Montreal, Quebec, Canada, 1973, pp. 235–261.

12.

Rowe

R. K.

, and Pells

P. J. N.

. A Theoretical Study of Pile-Rock Socket Behavior. International Conference on Structural Foundations on Rock, Sydney, Australia, 1980, pp. 253–264.

13.

Kwon

O. S.

Effect of Rock Mass Weathering on Resistant Behavior of Drilled Shaft Socketed into Weathered Rock. PhD thesis. Seoul National University, Seoul, South Korea, 2004.