Numerical study of Tunis soft soil improved by combined vacuum consolidation and geodrains

What is it about?

This paper presents a numerical study of the behaviour of Tunis soft soil improved by vacuum consolidation combined with geodrains. An experimental investigation was carried out on reconstituted samples of Tunis soft soil (TSS). Three consolidation tests were carried out in a cell of 126- mm inner diameter and 290-mm height, the first one included a consolidation test by preload stress (q=100 kPa). In the second test, vacuum consolidation tests (pv=100 kPa) were performed. The third test comprised a vacuum consolidation test combined with the preload (pv=50 kPa and q=50 kPa). Simulation of those tests by the finite-element PLAXIS-2D code was implemented in axisymmetric conditions. Soft soil model was used to describe the behavior of Tunis soft soil (TSS). During this simulation, a parametric study was performed by varying the horizontal permeability of TSS. Then, by comparing the numerical results to the recorded data in laboratory, it has been verified that the predicted settlements are higher than those measured during the performed laboratory tests. Further, numerical results confirmed that when the coefficient kh increases, the consolidation is complete in a shorter time. This work highlighted the usefulness of combining the vacuum pressure and geodrains improvement techniques to improve the behaviour of Tunis soft soil.

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Why is it important?

The combination of two ground improvement techniques is benficial to accelerate much better the conslidation of a soft clay, much better than the classical geodrains technique.

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