Simplified Method for Calculating Consolidation Degree of Deep Mixed Column–Improved Soft Soils
Publication: International Journal of Geomechanics
Volume 22, Issue 8
Abstract
Deep mixing method has been widely used to improve soft soils by increasing bearing capacity, reducing total and differential settlements, and enhancing stability. Experimental and numerical studies have demonstrated that the inclusion of deep-mixed (DM) columns in soft soils (e.g., clays and silts) could accelerate the consolidation of soft soils. Existing theoretical solutions for calculating the consolidation degree of DM column-improved soft soils are mostly complicated and not easy to use for practical applications. Therefore, a simple analytical solution is needed to calculate the consolidation degree of DM column-improved soft soils. In this study, a unit cell concept was used to develop a simplified method for calculating the consolidation degree of DM column-improved soft soils under a rigid footing. The simplified method considers the stress transfer between columns and their surrounding soil under elastic conditions and the vertical drainage of columns and their surrounding soils. The proposed simplified method is verified after compared with the numerical analysis considering four key influence factors on the consolidation degree of DM column-improved soft soils. The key influence factors include the soil thickness to unit-cell diameter ratio, the area replacement ratio, the modulus ratio of DM columns to soil, and the permeability ratio of DM columns to soil. The proposed simplified solution also captures the characteristics of the consolidation behavior of DM column-improved soft soils by considering stress transfer between columns and soil during consolidation and is easy to use in practice. Three existing analytical solutions are used for the comparisons with the proposed method. Among these methods, the proposed method has the best estimation of the consolidation degree for the DM column-improved soft soils under most conditions. It is recommended that the proposed method should be used for the condition where column permeability is close to soil permeability.
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References
Åhnberg, H. 2003. “Measured permeabilities in stabilized Swedish soils.” In Proc., 3rd Int. Conf. on Grouting and Ground Treatment. Reston, VA: ASCE.
Alamgir, M., N. Miura, H. B. Poorooshasb, and M. R. Madhav. 1996. “Deformation analysis of soft ground reinforced by columnar inclusions.” Comput. Geotech. 18 (4): 267–290. https://doi.org/10.1016/0266-352X(95)00034-8.
Broms, B. B. 1999. “The design of lime, lime/cement and cement columns.” In Proc., Int. Conf. on Deep Mix Method for Deep Soil Stabilisation, 125–153.
Bruce, M. E. C., R. R. Berg, J. G. Collin, G. M. Filz, M. Terashi, and D. S. Yang. 2013. Federal highway administration design manual: Deep mixing for embankment and foundation support. Publication No. FHWA-HRT-13-046. Washington, DC: Federal Highway Administration.
Castro, J., and C. Sagaseta. 2009. “Consolidation around stone columns. Influence of column deformation.” Int. J. Numer. Anal. Methods Geomech. 33 (7): 851–877.
Chai, J. C., and S. Pongsivasathit. 2009. “Prediction of consolidation settlements of floating column improved soft clayed subsoil.” In Proc., of Int. Symp. on Geotechnical Eng., Ground Improvement and Geosynthetic for Sustainable Mitigation and Adaptation to Climate Change including Global Warming, Bangkok: Thailand, 107–115. London: ISSMGE.
Chai, J. C., S. L. Shen, N. Miura, and D. T. Bergado. 2001. “Simple method of modeling PVD-improved subsoil.” J. Geotech. Geoenviron. Eng. 127 (11): 965–972. https://doi.org/10.1061/(ASCE)1090-0241(2001)127:11(965).
Han, J. 2015. Principles and practice of ground improvement. Hoboken, NJ: Wiley. June, 432p.
Han, J. 2021. “Evaluation of settlement calculation method for deep mixed soft foundations.” In Proc., of Deep Mixing, 9. Hawthorne, NJ: Deep Foundations Institute.
Han, J., J. F. Chen, Z. S. Hong, and S. L. Shen. 2010. “Mitigation of levee failures using deep mixed columns and geosynthetics.” Geomech. Geoeng.: An Int. J. 5 (1): 49–55.
Han, J., R. J. Parsons, A. R. Sheth, and J. Huang. 2005. “Factors of safety against deep-seated failure of embankments over deep mixed columns.” In Vol. 1.2 of Proc. of Deep Mixing 2005 Conf., 231–236. Linköping, Sweden: Swedish Geotechnical Institute.
Han, J., and S.-L. Ye. 2001. “Simplified method for consolidation rate of stone column reinforced foundations.” J. Geotech. Geoenviron. Eng. 127 (7): 597–603. https://doi.org/10.1061/(ASCE)1090-0241(2001)127:7(597).
Han, J., and S. L. Ye. 2002. “A theoretical solution for consolidation rates of stone column-reinforced foundations accounting for smear and well resistance effects.” Int. J. Geomech. 2 (2): 135–151. https://doi.org/10.1061/(ASCE)1532-3641(2002)2:2(135).
Han, J., X. M. Yang, J. F. Chen, and A. Porbaha. 2009. “Settlement calculation of deep mixed foundations.” In Proc., of Int. Symp. on Deep Mixing and Admixture Stabilization, edited by M. Kitazume, and M. Terashi, 4. Yokosuka, Japan: Port and Airport Research Institute.
Horpibulsuk, S., A. Chinkulkijniwat, A. Cholphatsorn, J. Suebsuk, and M. D. Liu. 2012. “Consolidation behavior of soil–cement column improved ground.” Comput. Geotech. 43: 37–50. https://doi.org/10.1016/j.compgeo.2012.02.003.
Huang, J., J. Han, and S. Oztoprak. 2009. “Coupled mechanical and hydraulic modeling of geosynthetic-reinforced column-supported embankments.” J. Geotech. Geoenviron. Eng. 135 (8): 1011–1021. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000026.
Jiang, Y., J. Han, and G. Zheng. 2013. “Numerical analysis of consolidation of soft soils fully-penetrated by deep-mixed columns.” KSCE J. Civ. Eng. 17 (1): 96–105. https://doi.org/10.1007/s12205-013-1641-x.
Jiang, Y., J. Han, and G. Zheng. 2014. “Influence of column yielding on degree of consolidation of soft foundations improved by deep mixed columns.” Geomech. Eng. 6 (2): 173–194. https://doi.org/10.12989/gae.2014.6.2.173.
Kitazume, M., K. Okano, and S. Miyajima. 2000. “Centrifuge model tests on failure envelope of column type deep mixing method improved ground.” Soils Found. 40 (4): 43–55. https://doi.org/10.3208/sandf.40.4_43.
Lorenzo, G. A., and D. T. Bergado. 2003. “New consolidation equation for soil–cement piles improved ground.” Can. Geotech. J. 40 (2): 265–275. https://doi.org/10.1139/t02-114.
Miao, L., X. Wang, and E. Kavazanjian. 2008. “Consolidation of a double-layered compressible foundation partially penetrated by deep mixed columns.” J. Geotech. Geoenviron. Eng. 134 (8): 1210–1214. https://doi.org/10.1061/(ASCE)1090-0241(2008)134:8(1210).
Navin, M. P., and G. M. Filz. 2006. “Numerical stability analysis of embankments supported on deep mixed columns.” In Ground Modification and Seismic Mitigation, Geotechnical Special Publication 152, edited by A. Porbaha, S.-L. Shen, J. Wartman, and J.-C. Chai, 1–8. Reston, VA: ASCE.
Oliveira, P. J. V., J. L. P. Pinheiro, and A. A. S. Correia. 2011. “Numerical analysis of an embankment built on soft soil reinforced with deep mixing columns: Parametric study.” Comput. Geotech. 38 (4): 566–576. https://doi.org/10.1016/j.compgeo.2011.03.005.
Wang, G. 2009. “Consolidation of soft clay foundations reinforced by stone columns under time-dependent loadings.” J. Geotech. Geoenviron. Eng. 135 (12): 1922–1931. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000178.
Xie, K.-H., M.-M. Lu, A.-F. Hu, and G.-H. Chen. 2009. “A general theoretical solution for the consolidation of a composite foundation.” Comput. Geotech. 36 (1–2): 24–30. https://doi.org/10.1016/j.compgeo.2008.02.012.
Yin, J.-H., and Z. Fang. 2006. “Physical modelling of consolidation behaviour of a composite foundation consisting of a cement-mixed soil column and untreated soft marine clay.” Géotechnique 56 (1): 63–68. https://doi.org/10.1680/geot.2006.56.1.63.
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International Journal of Geomechanics
Volume 22 • Issue 8 • August 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Oct 16, 2021
Accepted: Feb 25, 2022
Published online: May 26, 2022
Published in print: Aug 1, 2022
Discussion open until: Oct 26, 2022
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Cited by
- Fengrui Rao, Yan Xu, Zhen Zhang, Guanbao Ye, Tianxiong Chen, Analytical Solution for Consolidation of Soft Soil with Partially Penetrated Stiffened Deep-Mixed Columns under an Embankment, International Journal of Geomechanics, 10.1061/IJGNAI.GMENG-9281, 24, 6, (2024).