Large-Strain Vacuum-Assisted Consolidation with Non-Darcian Radial Flow Incorporating Varying Permeability and Compressibility
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 143, Issue 1
Abstract
A numerical solution has been developed for large-strain consolidation incorporating non-Darcian (nonlinear) radial flow with varying compressibility and permeability coefficients. The solution can accommodate both conventional fill surcharge as well as vacuum preloading. The smear effect caused by mandrel-driven vertical drains is also captured in the analysis. The proposed model is verified by comparing it with FEM simulation, existing laboratory data, other existing theoretical solutions, and its advantage of capturing the multiple factors influencing radial drainage and consolidation is demonstrated. The effects of non-Darcian flow are found to be significant for obtaining an accurate solution, unlike numerous past solutions that are based on linear Darcy flow. The salient finding of this study is that the conventional small-strain theory can overestimate the rate of consolidation with radial drainage, especially for highly compressible soils such as estuarine clays under substantial preloading pressures. It is also found that a considerable difference (larger than 5%) between large-strain and small-strain solutions inevitably occurs once the vertical strain exceeds approximately 15%, which can be regarded as a threshold beyond which the large-strain analysis becomes increasingly important. The proposed model is applied to a case study at Ballina Bypass (NSW, Australia), where prefabricated vertical drains have been installed in soft estuarine clay subjected to a combination of fill surcharge and vacuum preloading.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors acknowledge the support of the Australian Research Council (ARC) Centre of Excellence for Geotechnical Science and Engineering (CGSE). This study was initiated as the result of a past ARC-Linkage project with industry in view of Pacific Highway upgrading along the eastern coast of NSW, and in this regard sincere appreciation goes to Coffey Geotechnics (consultants), Douglas Partners (consultants) and Roads and Maritime Services of NSW (public transport organization) for their keen collaboration and for facilitating the research outcomes to be adopted in practical situations facing the challenges of soft clays.
References
ABAQUS version 6.12 [Computer software]. Dassault Systèmes, Waltham, MA.
Barron, R. A. (1948). “Consolidation of fine-grained soils by drain wells.” Trans. ASCE, 113(1), 718–742.
Basu, D., and Prezzi, M. (2007). “Effect of the smear and transition zones around prefabricated vertical drains installed in a triangular pattern on the rate of soil consolidation.” Int. J. Geomech., 34–43.
Basu, D., Prezzi, M., and Madhav, M. R. (2010). “Effect of soil disturbance on consolidation by prefabricated vertical drains installed in a rectangular pattern.” Geotech. Geol. Eng., 28(1), 61–77.
Bergado, D., Asakami, H., Alfaro, M., and Balasubramaniam, A. (1991). “Smear effects of vertical drains on soft Bangkok clay.” J. Geotech. Eng., 1509–1530.
Fox, P. J., and Berles, J. D. (1997). “CS2: A piecewise-linear model for large strain consolidation.” Int. J. Numer. Anal. Methods Geomech., 21(7), 453–475.
Fox, P. J., Di Nicola, M., and Quigley, D. W. (2003). “Piecewise-linear model for large strain radial consolidation.” J. Geotech. Geoenviron. Eng., 940–950.
Geng, X., Indraratna, B., and Rujikiatkamjorn, C. (2011). “Effectiveness of partially penetrating vertical drains under a combined surcharge and vacuum preloading.” Can. Geotech. J., 48(6), 970–983.
Gibson, R. E., England, G. L., and Hussey, M. J. L. (1967). “The theory of one-dimensional consolidation of saturated clays. Part I: Finite non-linear consolidation of thin homogeneous layers.” Géotechnique, 17(3), 261–273.
Gibson, R. E., Schiffman, R. L., and Cargill, K. W. (1981). “The theory of one-dimensional consolidation of saturated clays. Part II: Finite nonlinear consolidation of thick homogeneous layers.” Can. Geotech. J., 18(2), 280–293.
Hansbo, S. (1981). “Consolidation of fine-grained soils by prefabricated drains and lime column installation.” Proc., 10th Int. Conf. on Soil Mechanics and Foundation Engineering, Vol. 3, Balkema, Rotterdam, Netherlands, 677–682.
Hansbo, S. (1997). “Aspects of vertical drain design: Darcian or non-Darcian flow.” Géotechnique, 47(5), 983–992.
Hu, Y. Y., Zhou, W. H., and Cai, Y. Q. (2014). “Large-strain elastic viscoplastic consolidation analysis of very soft clay layers with vertical drains under preloading.” Can. Geot. J., 51(2), 144–157.
Indraratna, B., Balasubramaniam, A. S., and Ratnayake, P. (1994). “Performance of embankment stabilized with vertical drains on soft clay.” J. Geotech. Eng., 257–273.
Indraratna, B., Perera, D., Rujikiatkamjorn, C., and Kelly, R. (2015). “Soil disturbance analysis due to vertical drain installation.” Proc. ICE Geotech. Eng., 168(3), 236–246.
Indraratna, B., Rujikiatkamjorn, C., Kelly, R., and Buys, H. (2010). “Sustainable soil improvement via vacuum preloading.” Proc. ICE Ground Improv., 163(1), 31–42.
Indraratna, B., Rujikiatkamjorn, C., Kelly, R., and Buys, H. (2012). “Soft soil foundation improved by vacuum and surcharge loading.” Proc. ICE Ground Improv., 165(2), 87–96.
Indraratna, B., Rujikiatkamjorn, C., and Sathananthan, I. (2005). “Radial consolidation of clay using compressibility indices and varying horizontal permeability.” Can. Geotech. J., 42(5), 1330–1341.
Kianfar, K., Indraratna, B., and Rujikiatkamjorn, C. (2013). “Radial consolidation model incorporating the effects of vacuum preloading and non-Darcian flow.” Géotechnique, 63(12), 1060–1073.
Onoue, A. (1988). “Consolidation by vertical drains taking well resistance and smear into consideration.” Soils Found., 28(4), 165–174.
Peters, G. P., and Smith, D. W. (2002). “Solute transport through a deforming porous medium.” Int. J. Numer. Anal. Methods Geomech., 26(7), 683–717.
Rujikiatkamjorn, C., and Indraratna, B. (2007). “Analytical solutions and design curves for vacuum-assisted consolidation with both vertical and horizontal drainage.” Can. Geotech. J., 44(2), 188–200.
Sathananthan, I., and Indraratna, B. (2006). “Plane-strain lateral consolidation with non-Darcian flow.” Can. Geotech. J., 43(2), 119–133.
Tavenas, F., and Leroueil, S. (1980). “The behaviour of embankments on clay foundations.” Can. Geotech. J., 17(2), 236–260.
Tavenas, P., Jean, P., Leblond, P., and Leroueil, S. (1983). “The permeability of natural soft clays. Part II: Permeability characteristics.” Can. Geotech. J., 20(4), 645–660.
Voottipruex, P., Bergado, D. T., Lam, L. G., and Hino, T. (2014). “Back-analyses of flow parameters of PVD improved soft Bangkok clay with and without vacuum preloading from settlement data and numerical simulations.” Geotext. Geomembr., 42(5), 457–467.
Walker, R., Indraratna, B., and Rujikiatkamjorn, C. (2012). “Vertical drain consolidation with non-Darcian flow and void-ratio-dependent compressibility and permeability.” Géotechnique, 62(11), 985–997.
Watabe, Y., and Leroueil, S. (2012). “Modeling and implementation of the isotache concept for long-term consolidation behavior.” Int. J. Geomech., A4014006.
Xie, K. H., and Leo, C. J. (2004). “Analytical solutions of one-dimensional large strain consolidation of saturated and homogeneous clays.” Comput. Geotech., 31(4), 301–314.
Yan, S. W., and Chu, J. (2005). “Soil improvement for a storage yard using the combined vacuum and fill preloading method.” Can. Geotech. J., 42(4), 1094–1104.
Yin, J. H., and Graham, J. (1989). “Viscous-elastic-plastic modelling of one-dimensional time-dependent behaviour of clays.” Can. Geotech. J., 26(2), 199–209.
Zhu, G. F., and Yin, J. H. (2004). “Consolidation analysis of soil with vertical and horizontal drainage under ramp loading considering smear effects.” Geotext. Geomembr., 22(1–2), 63–74.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 143 • Issue 1 • January 2017
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Apr 10, 2015
Accepted: Jun 22, 2016
Published online: Aug 2, 2016
Published in print: Jan 1, 2017
Discussion open until: Jan 2, 2017
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.