Numerical Investigation of Embankment Settlement Improved by Method of Preloading by Vertical Drains

Authors: Seyed Abolhasan Naeini, Saeideh Mohammadi

Abstract:

Time dependent settlement due to loading on soft saturated soils produces many problems such as high consolidation settlements and low consolidation rates. Also, long term consolidation settlement of soft soil underlying the embankment leads to unpredicted settlements and cracks on soil surface. Preloading method is an effective improvement method to solve this problem. Using vertical drains in preloading method is an effective method for improving soft soils. Applying deep soil mixing method on soft soils is another effective method for improving soft soils. There are little studies on using two methods of preloading and deep soil mixing simultaneously. In this paper, the concurrent effect of preloading with deep soil mixing by vertical drains is investigated through a finite element code, Plaxis2D. The influence of parameters such as deep soil mixing columns spacing, existence of vertical drains and distance between them, on settlement and stability factor of safety of embankment embedded on soft soil is investigated in this research.

Keywords: Preloading, soft soil, vertical drains, deep soil mixing, consolidation settlement.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.2363332

References:

[1] Zhu, W., Yan, J., & Yu, G. (2018). Vacuum preloading method for land reclamation using hydraulic filled slurry from the sea: A case study in coastal China. Ocean Engineering, 152, 286-299.
[2] Zhang, Z., Ye, G. B., & Xu, Y. (2018). Comparative analysis on performance of vertical drain improved clay deposit under vacuum or surcharge loading. Geotextiles and Geomembranes, 46(2), 146-154.
[3] Stamatopoulos, C. A., Lopez-Caballero, F., & Modaressi-Farahmand-Razavi, A. (2015). The effect of preloading on the liquefaction cyclic strength of mixtures of sand and silt. Soil Dynamics and Earthquake Engineering, 78, 189-200.
[4] Indraratna, B., Redana, I.W., 2000. Numerical modeling of vertical drains with smear and well resistance. Can. Geotech. J. 37 (1), 132–145.
[5] Mesri, G., and Khan, A. Q. (2012). “Ground improvement using vacuum loading together with vertical drains.” J. Geotech. Geoenviron. Eng., 10.1061/(ASCE)GT.1943-5606.0000640, 680–689.
[6] Larsson, S., Adevik, S., Ignat, R., & Baker, S. (2014). A case study on the effect of using surcharge fill as a complement to ground improvement with dry deep mixing. In DFI/EFFC International Conference on Piling and Deep Foundations (Sweden/EU), May 21-23 in Stockholm, Sweden. Deep Foundations Institute.
[7] Brinkgereve, R. B. J., & Vermeer, P. A. (2003). PLAXIS Version 8 material model manual. DELFT University of Technology & PLAXIS BV, Pays-Bas.
[8] Hird CC, Pyrah IC, Russell D and Cinicioglu F (1995) Modelling the effect of vertical drains in two-dimensional finite element analyses of embankments on soft ground. Canadian Geotechnical Journal 32(5): 795–807.