Boundary Effects of Pile Cap on the Integrity Testing of Group Piles
Low-strain surface reflection pile integrity testing (PIT) methods have been successfully used for the quality assurance of newly-built individual piles. However, for existing piles with pile cap, previous studies have shown that the stress-wave reflected from the boundaries of pile cap may cause difficulties in determining their integrity. In this paper, the boundary effects of pile cap on the signal of PITs were studied by numerical simulation and tests on model piles. Feasibility of minimizing the boundary effects by embedded accelerometers was also investigated. Results from this study indicate that signals obtained from numerical simulation are similar to those obtained from tests performed on model piles. It also shows that boundary effects of pile cap on low strain pile integrity tests can be reduced by using embedded accelerometers, thus making it easier to assess the integrity of piles with a pile cap.
The work presented in this paper is sponsored by the Ministry of Science and Technology (formerly National Science Council) of Taiwan, R.O.C. under Grant No. NSC 102-2221-E-324-011-MY3. Their support is deeply appreciated.
- ASTM: Standard Test Method for Low Strain Integrity Testing of Piles. D5882-00, Book of Standards Volume 04.09. ASTM International, West Conshohocken, PA (2000)Google Scholar
- Davis, A., Dunn, C.: From theory to field experience with the nondestructive testing of piles. Proc. Inst. Civil Eng. 57(Part 2), 571–593 (1974)Google Scholar
- Fukuhara, T., Kakurai, M., Sugimoto, M.: Analytical evaluation of defective piles. In: Proceedings 4th International Conference on Application of Stress-Wave Theory to Piles, Hague, The Netherlands, 1992, pp. 563–569Google Scholar
- Han, B.W., Wang, D.G.: Application of sonic tomography in the integrity testing of concrete piles. In: Proceedings, the 4th International Conference on the Application of Stress-Wave Theory to piles, Hauge, Netherlands, 1992, pp. 231–234Google Scholar
- Hollema, D.A., Olson, L.D.: Crosshole sonic logging and velocity tomography imaging of drilled shaft foundations. In: Proceedings of NDT-CE 2003, Berlin, Germany, 2003Google Scholar
- Lai, J., Yang, P.C, Yang, B.H., Chang, D.W.: Integrity testing of model pile with embedded accelerometers. In: Proceedings 2017 International Conference on Transportation Infrastructure and Materials, Qingdao, China, 2017, pp. 801–808Google Scholar
- Olson, L.D., Jalinoos, F., Aouad, M.F.: Determination of Unknown Subsurface Bridge Foundations. NCHRP 21-5 Project Report, Transportation Research Board, 1998, p. 71Google Scholar
- Stain, R.T., Williams, H.T.: Interpretation of sonic coring results: a research project. In: Proceedings, the 4th International DFI Conference, Balkema, 1991, pp. 633–640Google Scholar
- Steinbach, J., Vey, E.: Caisson evaluation by stress wave propagation method. J. Geotech. Eng. Div., ASCE 101(GT4), 361–378 (1975)Google Scholar
- Wu, S., Lai, J., Cheng, C.F., Yang, B.H.: Integrity testing of model piles with pile cap. In: Proceedings of NDT-CE 2015, Berlin, Germany, 2015, pp. 920–927Google Scholar