Parametric study of improvement of Leda clay Stiffness due to Columns Installation
Volume Title: ICASGE2025
Paper ID : 1037-ICASGE-FULL
Authors
Abstract
The current methods available in the literature for the design of column-reinforced soils tend to overestimate the in-situ soil substitution ratio. This is confirmed by the difficulty experienced on-site in incorporating the predicted quantity of granular material, as proven by field control tests. In fact, these methods do not consider the significant improvement in the characteristics of the surrounding Leda soft clay due to the installation technique.
This paper illustrates the influence of parameters involved in the increase of the stiffness modulus of clay after vibro-compacted stone column installation. A numerical procedure is therefore implemented to simulate the installation of a stone column in a clay deposit.
The installation of the column was simulated as a lateral expansion in the surrounding clay. A hardening soil model is considered for the clay to simulate stress-stiffness dependency. The stiffness parameters were determined and calibrated using oedometer and triaxial tests results.
The influence of parameters such as the spacing between columns, etc. was studied by analyzing the stress states in the soft clay surrounding the column after a period of consolidation. Numerical analyses were conducted to predict the increase in clay stiffness. By calculating the increase in the effective stress ratio, the increase of the stiffness of the surrounding clay around the column was estimated. Taking into account the improved stiffness of the soft clay could lead to substantial savings in the amount of stone required, compared with current design practice. This improvement of clay modulus varies with the considered parameters.
This paper illustrates the influence of parameters involved in the increase of the stiffness modulus of clay after vibro-compacted stone column installation. A numerical procedure is therefore implemented to simulate the installation of a stone column in a clay deposit.
The installation of the column was simulated as a lateral expansion in the surrounding clay. A hardening soil model is considered for the clay to simulate stress-stiffness dependency. The stiffness parameters were determined and calibrated using oedometer and triaxial tests results.
The influence of parameters such as the spacing between columns, etc. was studied by analyzing the stress states in the soft clay surrounding the column after a period of consolidation. Numerical analyses were conducted to predict the increase in clay stiffness. By calculating the increase in the effective stress ratio, the increase of the stiffness of the surrounding clay around the column was estimated. Taking into account the improved stiffness of the soft clay could lead to substantial savings in the amount of stone required, compared with current design practice. This improvement of clay modulus varies with the considered parameters.
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