Effective stress analysis of piles in liquefiable soil
A case study of a bridge foundation
When evaluating the seismic performance of pile foundations in liquefiable soils, it is critically important to estimate the effects of cyclic ground displacements on the pile response. Advanced analyses based on the effective stress principle account for these effects in great detail by simulating the process of pore pressure build-up and associated stress-strain behaviour of soils. For this reason, the effective stress method has been established as a principal tool for the analysis and assessment of seismic performance of important engineering structures.
In this paper, effective stress analysis is applied to a case study of a bridge pier founded on piles in liquefiable soil. The study examines the likely effects of liquefaction, cyclic ground displacements and soil-structure interaction on the bridge foundation during a strong earthquake. A fully coupled effective stress method of analysis is used to compute the dynamic response of the soil-pile-bridge system. In the analysis, an elastoplastic deformation law based on a state concept interpretation is used for modelling nonlinear behaviour of sand. The seismic performance of the pile foundation is discussed using computed time histories and maximum values of ground and pile displacements, excess pore water pressure and pile bending moments. The advantages of the effective stress analysis are discussed through comparisons with a more conventional pseudo-static analysis of piles.
Biot, M. A. Theory of propagation of elastic waves in a fluidsaturated porous solid, Part I -low frequency range; Part II – higher frequency range. (1956) Journal of Acoustics Society of America; 28, 168-191. DOI: https://doi.org/10.1121/1.1908241
Bowen, H. and Cubrinovski, M. (2008). "Pseudo-static analysis of piles in liquefied soils: a case study of a bridge foundation" Bulletin of the New Zealand Society for Earthquake Engineering, 41(4), 234-246. DOI: https://doi.org/10.5459/bnzsee.41.4.234-246
Cubrinovski, M., Ishihara, K. and Higuchi, Y. (1995). "Verification of a constitutive model for sand by seismic centrifuge tests." IS-Tokyo '95 First Int. Conference on Earthquake Geotechnical Engineering. Tokyo 1995; (2), 669-674.
Cubrinovski, M., Ishihara, K. and Tanizawa. (1996). "Numerical simulation of Kobe Port Island liquefaction." 11th World Conference on Earthquake Engineering, Acapulco, Mexico (Paper No. 330).
Cubrinovski, M. and Ishihara, K. (1998a). "State concept and modified elastoplasticity for sand modelling." Soils and Foundations, 38(4), 213-225. DOI: https://doi.org/10.3208/sandf.38.4_213
Cubrinovski, M. and Ishihara, K. (1998b). "Modelling of sand behaviour based on state concept." Soils and Foundations, 38(3), 115-127. DOI: https://doi.org/10.3208/sandf.38.3_115
Cubrinovski, M., Ishihara, K. and Furukawazono, K. (1999). "Analysis of full-scale tests on piles in deposits subjected to liquefaction." Second International Conference on Earthquake Geotechnical Engineering, Lisboa 1999, 567-572.
Cubrinovski, M., Ishihara, K. and Furukawazono, K. (2000). "Analysis of two case histories on liquefaction of reclaimed deposits." Proc. 12th World Conference on Earthquake Engineering. Auckland 2000; CD-ROM, 1618/5.
Cubrinovski, M., Ishihara, K. and Kijima, T. (2001). "Effects of liquefaction on seismic response of a storage tank on pile foundations." Fourth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. San Diego 2001; CDROM, 6.15.
Cubrinovski, M., Uzuoka, R., Sugita H., Tokimatsu K., Sato M., Tsukamoto, Y., Ishihara, K., Kamata, T. (2008). "Prediction of pile response to lateral spreading by 3-D soil-water coupled dynamic analysis: shaking in the direction of ground flow”, Soil Dynamics and Earthquake Engineering, Elsevier, Vol. 28 (6), 421-435.
Howard, M., Nicol, A., Campbell, L. and Pettinga, J. (2005). "Holocene paleoearthquakes on the strike-slip Porters Pass Fault, Canterbury, New Zealand." New Zealand Journal of Geology and Geophysics, 48, 59-74. DOI: https://doi.org/10.1080/00288306.2005.9515098
Ishihara, K. and Cubrinovski, M. (2005). "Characteristics of Ground Motion in Liquefied Deposits During Earthquakes", Journal of Earthquake Engineering, 9(1), 1-15. DOI: https://doi.org/10.1080/13632460509350577
Pettinga, J., Yetton, M., Van Dissen, R. J. and Downes, G. (2001). "Earthquake source identification and characteristation for the Canterbury Region, South Island, New Zealand." Bulletin of the New Zealand Society for Earthquake Engineering, 34(4), 282-316. DOI: https://doi.org/10.5459/bnzsee.34.4.282-317
Stirling, M., Pettinga, J., Berryman, K. and Yetton, M. (2001). "Probabilistic seismic hazard assessment of the Canterbury region, New Zealand." Bulletin of the New Zealand Society for Earthquake Engineering, 34(4), 318-334. DOI: https://doi.org/10.5459/bnzsee.34.4.318-334
Tokimatsu, K. and Asaka, Y. (1998). "Effects of liquefaction induced ground displacements on pile performance in the 1995 Hyogoken-Nambu Earthquake." Soils and Foundations (Special Issue), 163-177. DOI: https://doi.org/10.3208/sandf.38.Special_163
Youd, T. L., Idriss, I. M., Andrus, R. D., Arango, I., Castro, G., Christian, J. T., Dobry, R., Liam Finn, W. D., Harder L.F, Jr., Hynes, M. E., Ishihara, K., Koester, J. P., Liao, S. S. C., Marcuson III, W. F., Martin, G. R., Mitchell, J. K., Moriwaki, Y., Power, M. S., Robertson, P. K., Seed, R. B. and Stokoe Ii, K. H. (2001). "Liquefaction resistance of soils: Summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluation of liquefaction resistance of soils." Journal of Geotechnical and Geoenvironmental Engineering, 127(10), 817-833. DOI: https://doi.org/10.1061/(ASCE)1090-0241(2001)127:10(817)
Zienkiewicz, O. C. and Shiomi, T. (1984). "Dynamic Behaviour of Saturated Porous Media: the Generalised Biot Formulation and its Numerical Solution." International Journal for Numerical and Analytical Methods in Geomechanics, 8(1), 71-96. DOI: https://doi.org/10.1002/nag.1610080106