Interpretation of Layer Boundaries and Shear Strengths for Stiff-Soft-Stiff Clays Using Cone Penetration Test: LDFE Analyses
Publication: International Journal of Geomechanics
Volume 17, Issue 9
Abstract
This paper reports on a new framework for interpreting cone penetrometer data in stiff-soft-stiff deposits, with the aim at identifying layer boundaries and interpreting accurately the undrained shear strength for each layer. An extensive parametric study was conducted using large deformation finite-element (LDFE) analyses. The LDFE results were used to establish the interpretation framework. Regardless of the strength and the rigidity index ratio between two successive layers, where the cone penetrates from stiff to soft clay layers and the reverse, the layer interface can be demarked at 1.3 D (D is the cone diameter) above and 0.8 D below the gradient discontinuity on the penetration resistance profile in the soft layer. The undrained shear strengths of the first and third (stiff) layers can be interpreted using a single-layer approach and the resistance profile without the influence of the adjacent soft layer. The interpretation for the interbedded second layer necessitates implementing a correction factor, which is shown to be a function of the relative thicknesses of the first and second layers, and the rigidity indexes and strength ratios of the adjacent layers. By combining the findings with the results from a previous study on an interbedded stiff clay layer, a complete design chart is proposed for a thin soft or stiff layer embedded in a thick clay layer. The proposed design framework is illustrated by a flowchart for practical use.
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Acknowledgments
The research presented here was undertaken with support from the Australian Research Council (ARC) Discovery Grant DP140103997. The fourth author is an ARC Discovery Early Career Researcher Award (DECRA) Fellow and is supported by ARC Project DE140100903. The work forms part of the activities of the Centre for Offshore Foundation Systems (COFS), currently supported as a node of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering and as a Centre of Excellence by the Lloyd’s Register Foundation. This support is gratefully acknowledged.
References
Ahmadi, M. M., and Robertson, P. K. (2005). “Thin-layer effects on the CPT qc measurement.” Can. Geotech. J., 42(5), 1302–1317.
Borel, D., Puech, A., Dendani, H., and Colliat, J.-L. (2005). “Deepwater geotechnical site investigation practice in the Gulf of Guinea.” Proc., 1st Int. Symp. on Frontiers in Offshore Geotechnics, S. Gourvenec and M. Cassidy, eds., CRC, Boca Raton, FL, 921–926.
Castleberry, J. P., II, and Prebaharan, N. (1985). “Clay crusts of the Sunda Shelf: A hazard to jack-up operations.” Proc., 8th Southeast Asian Geotechnical Conf., South East Asian Geotechnical Society, Pathumthani, Thailand, 40–48.
Chan, N., Paisley, J., and Holloway, G. (2008). “Characterization of soils affected by rig emplacement and Swiss cheese operations—Natuna Sea, Indonesia, a case study.” Proc., 2nd Jack-Up Asia Conf. and Exhibition, AP Energy Business Publications, Singapore.
Ehlers, C. J., Chen, J., Roberts, H. H., and Lee, Y. C. (2005). “The origin of near-seafloor ‘crust zones’ in deep water.” Proc., 1st Int. Symp. on Frontiers in Offshore Geotechnics, S. Gourvenec and M. Cassidy, eds., CRC, Boca Raton, FL, 927–933.
Handidjaja, P., Somehsa, P., and Manoj, M. (2004). “‘Swiss-cheese’—A method of degrading soil crust and minimizing risk to punch through problem on the installation of mobile offshore drilling unit (MODU).” Proc., 15th Southeast Asian Geotechnical Society Conf., Southeast Asian Geotechnical Society, Engineering Institute of Thailand, International Society of Soil Mechanics and Geotechnical Engineering, Pathumthani, Thailand, 303–306.
Herrmann, L. R. (1978). “Finite element analysis of contact problems.” J. Eng. Mech. Div., 104(5), 1043–1057.
Houlsby, G. T., and Martin, C. M. (2003). “Undrained bearing capacity factors for conical footings on clay.” Géotechnique, 53(5), 513–520.
Hu, Y., and Randolph, M. F. (1998a). “A practical numerical approach for large deformation problems in soil.” Int. J. Numer. Anal. Methods Geomech., 22(5), 327–350.
Hu, Y., and Randolph, M. F. (1998b). “H-adaptive FE analysis of elasto-plastic non-homogeneous soil with large deformation.” Comput. Geotech., 23(1-2), 61–83.
InSafeJIP. (2010). Improved guidelines for the prediction of geotechnical performance of spudcan foundations during installation and removal of jack-up units, RPS Energy, Woking, U.K.
Kostelnik, A., Guerra, M., Alford, J., Vazquez, J., and Zhong, J. (2007). “Jackup mobilization in hazardous soils.” SPE Drill. Complet., 22(1), 4–15.
Ladd, C. C., Foott, R., Ishihara, K., Schlosser, F., and Poulos, H. G. (1977). “Stress-deformation and strength characteristics.” Proc., 9th Int. Conf. on Soil Mechanics and Foundation Engineering, Japanese Society of Soil Mechanics and Foundation Engineering, Tokyo, 2, 421–94.
Ma, H., Zhou, M., Hu, Y., and Hossain, M. S. (2014). “Large deformation FE analyses of cone penetration in single layer non-homogeneous and three-layer soft-stiff-soft clays.” Proc., 33rd Int. Conf. on Ocean, Offshore and Arctic Engineering, ASME, New York.
Ma, H., Zhou, M., Hu, Y., and Hossain, M. S. (2016). “Interpretation of layer boundaries and shear strengths for soft-stiff-soft clays using CPT data: LDFE analyses.” J. Geotech. Geoenviron. Eng., 04015055.
McClelland, B., Young, A. G., & Remmes, B. D. (1981). “Avoiding jack-up rig foundation failures.” Proc., Symp. on Geotechnical Aspects of Coastal and Offshore Structures, CRC, Boca Raton, FL, 137–157.
Menzies, D., and Lopez, C. R. (2011). “Four atypical jack-up rig foundation case histories.” Proc., 13th Int. Conf. on the Jack-up Platform: Design, Construction and Operation, City Univ. London, London.
Menzies, D., and Roper, R. (2008). “Comparison of jackup rig spudcan penetration methods in clay.” Offshore Technology Conference, Houston.
Mo, P. Q., Marshall, A. M., and Yu, H. S. (2014). “Elastic-plastic solutions for expanding cavities embedded in two different cohesive-frictional materials.” Int. J. Numer. Anal. Methods Geomech., 38(9), 961–977.
Mo, P. Q., Marshall, A. M., and Yu, H. S. (2015). “Centrifuge modelling of cone penetration tests in layered soils.” Géotechnique, 65(6), 468.
Moss, R. E. S., Seed, R. B., Kayen, R. E., Stewart, J. P., Kiureghian, A. D., and Cetin, K. O. (2006). “CPT-based probabilistic and deterministic assessment of in situ seismic soil liquefaction potential.” J. Geotech. Geoenviron. Eng., 1032–1051.
Quirós, G. W., and Little, R. L. (2003). “Deepwater soil properties and their impact on the geotechnical program.” Offshore Technology Conference, Houston.
Randolph, M. F. (2004). “Characterisation of soft sediments for offshore applications.” Proc., 2nd Int. Conf. on Site Characterisation, Vol. 1, Millpress, Rotterdam, Netherlands, 209–231.
Robertson, P. K. (2009). “Interpretation of cone penetration tests—A unified approach.” Can. Geotech. J., 46(11), 1337–1355.
Robertson, P. K., and Fear, C. E. (1995). “Liquefaction of sands and its evaluation.” Proc., 1st Int. Conf. on Earthquake Geotechnical Engineering, Vol. 3, K. Ishihara, ed., A. A. Balkema, Rotterdam, Netherlands, 1253–1289.
Schneider, J. A., Randolph, M. F., Mayne, P. W., and Ramsey, N. R. (2008). “Analysis of factors influencing soil classification using normalized piezocone tip resistance and pore pressure parameters.” J. Geotech. Geoenviron. Eng., 1569–1586.
Vreugdenhil, R., Davis, R., and Berrill, J. R. (1994). “Interpretation of cone penetration results in multilayered soils.” Int. J. Numer. Anal. Methods Geomech., 18(9), 585–599.
Walker, J., and Yu, H. S. (2010). “Analysis of the cone penetration test in layered clay.” Géotechnique, 60(12), 939–948.
Xu, X., and Lehane, B. M. (2008). “Pile and penetrometer end bearing resistance in two-layered soil profiles.” Géotechnique, 58(3), 187–197.
Young, A. G., Remmes, B. D., and Meyer, B. J. (1984). “Foundation performance of offshore jack-up drilling rigs.” J. Geotech. Eng., 841–859.
Yue, Z. Q., and Yin, J. H. (1999). “Layered elastic model for analysis of cone penetration testing.” Int. J. Numer. Anal. Methods Geomech., 23(8), 829–843.
Zhou, M., Hossain, M. S., Hu, Y., and Liu, H. (2013). “Behaviour of ball penetrometer in uniform single-and double-layer clays.” Géotechnique, 63(8), 682–694.
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Published In
International Journal of Geomechanics
Volume 17 • Issue 9 • September 2017
Copyright
© 2017 American Society of Civil Engineers.
History
Received: May 20, 2016
Accepted: Feb 2, 2017
Published online: May 15, 2017
Published in print: Sep 1, 2017
Discussion open until: Oct 15, 2017
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