Papers by Mounir Bouassida
Geodata & AI, 2025
This paper suggests a new method for characterizing expansive soils by considering recorded data ... more This paper suggests a new method for characterizing expansive soils by considering recorded data from oedometer test, namely compression index (CC), swelling index (CS) and the swelling pressure (σS). Collected data included recorded values of the three parameters from 168 Tunisian soil samples and 41 soil samples from Algeria, Canada, France, Morocco and USA. Main finding was that when the CC/CS ratio is greater than 10, the soil is classified non-expansive with a swelling pressure lesser than 50 kPa. In turn, when CC/CS < 10, the soil is classified as expansive with a swelling pressure higher than 50 kPa when its clay content is above 35%. Whilst, for sand clays with clay content less than 30%, the swelling pressure is lower than 50 kPa despite the CC/CS ratio is lower than 10. For the classified Tunisian expansive soils, the cloud dots in (CC/CS; σS) plan is bounded between two parallel lines, thus suggesting the primary correlation based on the proposed method of characterization of expansive soils.
Keywords: Data-driven site characterization; Expansive soils; Oedometer test
Proc. of selected sessions Geo congress 2008. Special publications ASCE, 2008
The ultimate bearing capacity of an isolated stone column is studied. The soil surrounding the co... more The ultimate bearing capacity of an isolated stone column is studied. The soil surrounding the column is modeled by a constitutive law of plastic potential with variable flow. This recent model permits the calculation of the limit pressure of an expanded cylindrical cavity from which the ultimate bearing capacity is derived. Using recorded in situ data from load tests performed on thirteen isolated column models, the model parameters are identified. Comparison between experimental data and predictions by several models is discussed.
Proceedings of the International Conference on Ground Improvement and Ground Control, 2012
The behavior of remolded kaolin clay reinforced by stone column is investigated in laboratory. Th... more The behavior of remolded kaolin clay reinforced by stone column is investigated in laboratory. The installation of stone columns was simulated by performing a lateral expansion at different rates within hollow cylindrical remolded kaolin specimens initially subjected to K0 consolidation path. After the simulated column installation specimens were subjected to classical consolidated undrained triaxial tests with recorded excess pore pressure. The experimental program analyzed the effects of consolidation stress and the simulated installation of stone column on the improvement of undrained Young modulus and shear strength of kaolin clay. Obtained results showed, as result of column installation, a significant improvement of Young modulus when the cavity expansion ratio and the consolidation stress increase.
Additionally, the undrained shear strength of improved kaolin clay mainly increases at lower consolidation stress. Whilst, the ratio between undrained Young modulus and cohesion increases when the consolidation stress decreases.
Proceedings of the International Conference on Ground Improvement and Ground Control, 2012
The predictions of bearing capacity and settlement by using the group of columns model essentiall... more The predictions of bearing capacity and settlement by using the group of columns model essentially constitute the first required steps for the design of columnreinforced foundations. The bearing capacity of reinforced soft clay by sand and stone columns is evaluated trough the validation of laboratory and in situ experimental records. Based on all results, an overall methodology of design is comprehensively formulated for foundation on reinforced soils by columns. The suggested methodology, that is applicable to all practical projects, essentially aims to optimize the quantity of columns' material which controls the cost of reinforcement. Major conclusions derived from results of research work have been programmed in software, entitled "Columns". Several case studies have proved the usefulness of the software that offers a novel tool of design for foundations on reinforced soil by columns. The usefulness of developed software is shown through analysis of a study case of embankment on soft clay.
Touring Lecture ISSMGE Tunisia, 2006
1. La technique de renforcement par colonnes
1.1 Introduction
1.2 Remarques générales
1.3 L’expér... more 1. La technique de renforcement par colonnes
1.1 Introduction
1.2 Remarques générales
1.3 L’expérience tunisienne
2. Dimensionnement d’une fondation sur sol renforcé par colonnes
2.1 Capacité portante
2.2 Tassement
2.3 Colonnes sous semelle
2.4 Accélération de la consolidation
2.5 Risque de liquéfaction
2.6 Les autres méthodes
2.7 Récents développements
2.8 L’usage des logiciels
3. Illustration sur un exemple.
3.1. Capacité portante du sol renforcé
3.2 Tassement du sol renforcé
4. Conclusion
5. Références bibliographiques
1 st Mediterranean Geo Engineering Conference. Algeria, 2009
Properties and characteristics of soft clays are presented. Because several problems are faced, w... more Properties and characteristics of soft clays are presented. Because several problems are faced, when projects construction is intended on soft clays, several improvement techniques can be adopted. Preloading with or without vertical drains, vacuum consolidation and reinforcement by columns are currently used to enhance properties of soft clays. Also, rigid inclusions and geotextiles may be used. The principles and basic criteria for the design of all these techniques are explained. Comparison between advantages of improvement techniques is carried out by illustration of typical case histories.
Proc. 2nd Int. Conf. on Problematic Soils. December 3-5th 2006. Petaming Jaya, Salengor, Malaysia., 2006
This paper focuses, first, on problems related to the identification and classification of soft c... more This paper focuses, first, on problems related to the identification and classification of soft clays. The determination of physical parameters and mechanical characteristics of Tunis soft clay is presented. The
difficulties, that may lead to overestimated values of soil characteristics, is debated especially when tests are carried out on remolded soft clays. A method has been proposed to avoid overestimated undrained
cohesion from vane shear test. Then, the study of the behavior of soft clays is evoked. To model the
behavior of Tunis soft clay the modified Cam Clay (MCC) model is justified. Parameters of MCC model,
from experiments, are incorporated in Plaxis software (version 8.0) that served for assessment of the
observed behavior of Tunis soft clay. The possibility of improved performance of soft clays by stone
columns is presented. Because of lateral expansion during columns installation, and subsequent
consolidation prior to final loading, the parameters of soft clay are significantly improved. A methodology
based on numerical implementation by the use of Plaxis software permitted to evaluate the rate of increase of the modulus of elasticity of soft clay and the radius of the area surrounding the column where it occurs.
Keywords: soft clay , behaviour, model, improvement, experiments, remoulding, numerical, prediction.
Introduction à la géotechnique, 2011
Lorsque la construction d’un ouvrage est décidée sur un terrain
constitué d’un sol dit à problèm... more Lorsque la construction d’un ouvrage est décidée sur un terrain
constitué d’un sol dit à problèmes, en vue d'éviter la solution onéreuse et
classique de fondation profonde, il faut recourir à une opération
d’amélioration de sol. Cette dernière, des points de vue coût et délai
d'exécution, devra être avantageuse par rapport à toute autre solution de
fondation envisageable.
Lorsqu'une technique d’amélioration est décidée, une vérification
s'impose, au préalable, de la faisabilité de son exécution dans les
conditions géotechniques du projet visé et de la quantification des
performances pré dictées pour le sol amélioré. Cela implique la
réalisation de plots d’essais sur une plateforme limitrophe à
l’emplacement de l’ouvrage, ce qui pourrait amener de compléter la
campagne géotechnique déjà faite. Il y a lieu, donc, de comparer entre les
propriétés du sol initial avant et après l’opération d’amélioration, qui
s’accompagne de certaines performances qui conduiront à de nouvelles
propriétés et caractéristiques du sol initial. Les résultats de ces essais
servent également à la validation des méthodes de calcul adoptées lors du
dimensionnement spécifique à la technique d’amélioration exécutée.
Ce chapitre présente un panorama des techniques courantes
d'amélioration des sols en place des points de vue applicabilité et
avantages, exécution, dimensionnement et contrôle de suivi sur des
exemples illustrés à travers des projets réels.
Les techniques ici présentées sont : le pré chargement associé à des
drains verticaux, la consolidation sous vide, le renforcement par
colonnes, les inclusions rigides y compris les micro-pieux et le clouage.
Alors qu’à titre introductif un très succinct rappel est réservé aux
compactages statique et dynamique.
Annales de l'équipement, 2014
This paper focuses on the importance, for Tunisian entrepreneurs, to think about the usefulness o... more This paper focuses on the importance, for Tunisian entrepreneurs, to think about the usefulness of reinforcement of soft soils by columns due to their competitive cost in comparison to classical deep foundations. Current installation methods of reinforcement by columns are described in brief. Then, analysis of a case study shows the signficant reduction in cost when reinforcement by columns is suitably designed.
Revue Marocaine de génie civil, 1998
La détermination de la capacité portante d'une fondation sur sol renforcé par colonnes est entrep... more La détermination de la capacité portante d'une fondation sur sol renforcé par colonnes est entreprise dans le cadre du calcul à la rupture en considérant les modèles, tranchée, colonne isolée, cellule composite et groupe de colonnes
Afrique Science, 2011
The article presents the first geotechnical measurements carried out on clays of a geological for... more The article presents the first geotechnical measurements carried out on clays of a geological formation PlioQuaternary and from two sites affected the city of Mila. In the first part of this work, the geological
formation is detailed clay of the basin. Clay soils have been characterized in terms of their geotechnical
parameters are easiest to obtain in the laboratory (plasticity, blue value, clay content, etc...). We deduce a
ranking of their potential swelling and shrinkage for each of the sites studied. The second part is devoted to
analysis of microscopy can provide answers to explain the causes of swelling and shrinkage based on
mineralogical proportions.
Keywords : clay, shrinkage-swelling, disorder, geotechnical characterization.
Annales de l'Equipement, 2014
This paper focuses on the reinforcement of soft soils by the deep mixing technique. The determina... more This paper focuses on the reinforcement of soft soils by the deep mixing technique. The determination of bearing capacity equation and validation of analytical solutions by experimental recorded laoding tests are illustrated.
Desalination and Water Treatment, 2021
The global annual production of bottom ash as a waste of coal-burning has been rapid increases in... more The global annual production of bottom ash as a waste of coal-burning has been rapid increases in
the last decades. Therefore huge amounts of bottom ash have been disposed of in ash ponds areas
which pose a significant environmental problem. Bottom ash has quite similar engineering characteristics to natural sand, thus it can be used as a replacement for sand in various civil engineering
aspects; since it has been considered as a non-hazardous material. By utilizing bottom ash as a substitute material to sand, the ash storage areas problem can be solved; moreover, the cost of the project
will be reduced. This paper presents an experimental study performed on soft soil treated with a
group of floating bottom ash columns through physical model tests. The laboratory tests were conducted on the unreinforced soft ground and reinforced by floating bottom ash columns. For treated
cases, bottom ash columns of 25 mm diameter and 150 mm length were installed in the soft ground
with an area replacement ratio of 13%. The experimental test results revealed that the inclusion of
floating bottom ash columns in the soft soil ground enhances the carrying capacity and accelerates
the settlement compared to untreated ground.
Keywords: Foundation; Granular column; Ground improvement; Clay soil; Coal ash
Arabian Journal of Geosciences, 2023
The recyclability of wastes, especially mining waste, is one of the current challenges. Mines are... more The recyclability of wastes, especially mining waste, is one of the current challenges. Mines are subject to a well-defined life cycle planning to allow sustainable exploitation and development for the next generations. Mining techniques have developed considerably, so mining waste has become highly concentrated on pebbles. To build embankments and spoil heaps, it is necessary to know the mechanical properties of the composite mixture forming the mining waste. This paper tackles the calculation of the mechanical properties of highly heterogeneous mining wastes using a linear elasticity homogenization approach. Numerical models based on the finite element method are developed to determine the elastoplastic properties of the mixture. A first model enables the calculation of the Young's modulus and the Poisson's ratio of the mixture; then, based on an identification technique, a second model calculates the Mohr-Coulomb plasticity parameters. The obtained results show that the mixture is isotropic, and the mixture rigidity increases when the pebble concentration increases from 10 to 50%. Conversely, the volume maneuverability displayed by the Poisson's ratio decreases when the pebble concentrate increases. For the identified coefficients using Mohr-Coulomb model, the cohesion decreases from 9.13 to 5.59 kPa when the pebble concentration increases from 10 to 40%. The cohesion of the mixture remains higher compared to the cohesion of the limestone up to a concentration of 40%; it becomes 3.58 kPa. The mixture friction angle is always higher than the limestone friction angle.
Geotechnical Engineering - SEAGS & AGSSEA, 2021
This paper discusses the performance of Recharge Impulse Technology (RIT) in increasing the shaft... more This paper discusses the performance of Recharge Impulse Technology (RIT) in increasing the shaft capacity of deep foundation
systems regarding classical set-up processes. Based on the major contributors behind such performances: the shape effect and the electrical
discharge installation, a case study is analyzed in view of highlighting that the coupling of these two components leads to a reasonable
estimation of RIT shaft capacity with reference to in situ loading tests. A related design chart estimating the contribution of the shape effect in
the increase of the shaft capacity had been drawn and a mean power law was proposed through a parametric study on the adhesion factor.
R IOP Conf. Ser. Mater. Sci. Eng 932012055, 2020
Coal is considered one of the major sources of power-generation in Malaysia. The Coal-fired power... more Coal is considered one of the major sources of power-generation in Malaysia. The Coal-fired power plant is a kind of power plant that uses coal to generate electricity. The globally increasing demand for energy has led to an increase in the number of installation of coal-fired power plants. With the growth in coal-burning power plants, massive amounts of coal bottom ash have been produced as waste material. This article presents an experimental study on the geotechnical characteristics of Tanjung bin coal bottom ash and compares them with the properties of the natural granular soil focusing on the physical and mechanical characteristics namely; grain size distribution, specific gravity, compaction, permeability, shear strength, and relative density. Results revealed that the Tanjung bin bottom ash has geotechnical properties similar to the natural granular material, therefore it can be utilized as a substitute material to sand in several geotechnical application.
Geotechnical Engineering - SEAGS & AGSSEA, 2020
The accumulation of phosphogypsum (PG) produced till 2015 makes its management a real challenge t... more The accumulation of phosphogypsum (PG) produced till 2015 makes its management a real challenge to the Tunisian authorities and put the Tunisian Chemical Group (TCG) to face a challenge at large scale as the specified storage embankments knew considerable extensions in terms of heights and areas. Several studies were elaborated subsequently in 2007, 2012 and 2013 to focus on the stability of Sfax and Skhira PG embankments' and showed two different chemical and mechanical behaviours according to the experienced deposition process. In 2012, it was revealed that the wet PG embankment of Sfax City with 56m height, 53Ha area and 32° slope can attain 70m maximum height. This embankment can reach 100m in height if a reinforcement technique will be used. This deposition process is well recommended to ensure a better interaction between the embankment and the existing ground surface. Using the dry deposited process, the area of the PG embankment of Skhira City covers 112Ha and presents two elevation levels of 25m and 55m in 2013. However, the dry deposited process results in a damaged embankment profile, significant settlements and lateral displacements. Therefore, a PG embankment of 100m height cannot be targeted. A reinforcement of the embankment by High Density Polyethylene geotextile (HDPE) layers at increments of 4m from 55m elevation allows reaching 130m of height. Comparative study was raised between the wet and the dry process and resulted in favour of the wet process from both industrial and geotechnical perspectives. Thus, the TCG expects turning all its deposition processes to the wet one. A characterization of Tunisian Phosphogypsum was carried out based on the previous studies performed on Phosphogypsum embankments of Sfax and Skhira Cities and on the experimental tests performed on dry deposited Phosphogypsum. A numerical model is built in an attempt to propose an optimized solution to the PG specified storage areas.
Arabian Journal of Geosciences, 2020
This paper studied the numerical simulation of wet deposited Phosphogypsum (PG) embankment on an ... more This paper studied the numerical simulation of wet deposited Phosphogypsum (PG) embankment on an existing dry one by the Plaxis and Midas GTS geotechnical codes. Following the sequences of PG embankment construction, a plane strain model permitted the simulation of the conventional wet deposit process of PG. Mohr-Coulomb constitutive model with appropriate parameters describe the behavior of Tunisian Phosphogypsum residue. The implementation of suitable numerical procedure led to predict the evolution of settlements and horizontal displacements during the construction of PG embankment. Comparison between predictions by Plaxis and Midas codes overall showed similar trends, in particular, the occurrence of maximum settlements after the construction of peripheral basins located at the crest of PG embankment, while the lowest settlement occurs under the central basin located at the axis of whole PG embankment. For each stage of PG embankment construction, the predictions showed constant settlement. The adopted stage construction scheme highlighted alternated settlement and heave movements, from which observed in situ cracks within the PG deposited PG were justified.
Stability analysis of an embankment lying over a column reinforced soil
ABSTRACT The design against failure of an embankment resting upon a soft soil improved by a group... more ABSTRACT The design against failure of an embankment resting upon a soft soil improved by a group of columns is investigated with the help of the yield design homogenization approach. Assuming that both constituents of the reinforced ground are purely cohesive materials (‘lime column’ technique), an upper bound estimate for the macroscopic strength condition of the reinforced soil as a homogenized medium is first obtained, providing definite evidence of a shear strength anisotropy associated with the reinforcement preferential orientation. The kinematic method of yield design is then performed on the basis of such a criterion, making use of rotational failure mechanisms involving slip circles in the reinforced ground. Upper bound estimates are finally obtained for the embankment stability factor, as functions of the degree of reinforcement and relative thickness of the soil layer. These results are compared with those derived from a simplified analysis, where the reinforced soil is assumed to exhibit an averaged isotropic cohesion. This comparison clearly indicates that the latter simplified analysis may produce quite unsafe estimates for the embankment stability, which can be attributed to the fact that it fails to capture the inherent strength anisotropy of the reinforced soil. Copyright © 2010 John Wiley &amp; Sons, Ltd.
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Papers by Mounir Bouassida
Keywords: Data-driven site characterization; Expansive soils; Oedometer test
Additionally, the undrained shear strength of improved kaolin clay mainly increases at lower consolidation stress. Whilst, the ratio between undrained Young modulus and cohesion increases when the consolidation stress decreases.
1.1 Introduction
1.2 Remarques générales
1.3 L’expérience tunisienne
2. Dimensionnement d’une fondation sur sol renforcé par colonnes
2.1 Capacité portante
2.2 Tassement
2.3 Colonnes sous semelle
2.4 Accélération de la consolidation
2.5 Risque de liquéfaction
2.6 Les autres méthodes
2.7 Récents développements
2.8 L’usage des logiciels
3. Illustration sur un exemple.
3.1. Capacité portante du sol renforcé
3.2 Tassement du sol renforcé
4. Conclusion
5. Références bibliographiques
difficulties, that may lead to overestimated values of soil characteristics, is debated especially when tests are carried out on remolded soft clays. A method has been proposed to avoid overestimated undrained
cohesion from vane shear test. Then, the study of the behavior of soft clays is evoked. To model the
behavior of Tunis soft clay the modified Cam Clay (MCC) model is justified. Parameters of MCC model,
from experiments, are incorporated in Plaxis software (version 8.0) that served for assessment of the
observed behavior of Tunis soft clay. The possibility of improved performance of soft clays by stone
columns is presented. Because of lateral expansion during columns installation, and subsequent
consolidation prior to final loading, the parameters of soft clay are significantly improved. A methodology
based on numerical implementation by the use of Plaxis software permitted to evaluate the rate of increase of the modulus of elasticity of soft clay and the radius of the area surrounding the column where it occurs.
Keywords: soft clay , behaviour, model, improvement, experiments, remoulding, numerical, prediction.
constitué d’un sol dit à problèmes, en vue d'éviter la solution onéreuse et
classique de fondation profonde, il faut recourir à une opération
d’amélioration de sol. Cette dernière, des points de vue coût et délai
d'exécution, devra être avantageuse par rapport à toute autre solution de
fondation envisageable.
Lorsqu'une technique d’amélioration est décidée, une vérification
s'impose, au préalable, de la faisabilité de son exécution dans les
conditions géotechniques du projet visé et de la quantification des
performances pré dictées pour le sol amélioré. Cela implique la
réalisation de plots d’essais sur une plateforme limitrophe à
l’emplacement de l’ouvrage, ce qui pourrait amener de compléter la
campagne géotechnique déjà faite. Il y a lieu, donc, de comparer entre les
propriétés du sol initial avant et après l’opération d’amélioration, qui
s’accompagne de certaines performances qui conduiront à de nouvelles
propriétés et caractéristiques du sol initial. Les résultats de ces essais
servent également à la validation des méthodes de calcul adoptées lors du
dimensionnement spécifique à la technique d’amélioration exécutée.
Ce chapitre présente un panorama des techniques courantes
d'amélioration des sols en place des points de vue applicabilité et
avantages, exécution, dimensionnement et contrôle de suivi sur des
exemples illustrés à travers des projets réels.
Les techniques ici présentées sont : le pré chargement associé à des
drains verticaux, la consolidation sous vide, le renforcement par
colonnes, les inclusions rigides y compris les micro-pieux et le clouage.
Alors qu’à titre introductif un très succinct rappel est réservé aux
compactages statique et dynamique.
formation is detailed clay of the basin. Clay soils have been characterized in terms of their geotechnical
parameters are easiest to obtain in the laboratory (plasticity, blue value, clay content, etc...). We deduce a
ranking of their potential swelling and shrinkage for each of the sites studied. The second part is devoted to
analysis of microscopy can provide answers to explain the causes of swelling and shrinkage based on
mineralogical proportions.
Keywords : clay, shrinkage-swelling, disorder, geotechnical characterization.
the last decades. Therefore huge amounts of bottom ash have been disposed of in ash ponds areas
which pose a significant environmental problem. Bottom ash has quite similar engineering characteristics to natural sand, thus it can be used as a replacement for sand in various civil engineering
aspects; since it has been considered as a non-hazardous material. By utilizing bottom ash as a substitute material to sand, the ash storage areas problem can be solved; moreover, the cost of the project
will be reduced. This paper presents an experimental study performed on soft soil treated with a
group of floating bottom ash columns through physical model tests. The laboratory tests were conducted on the unreinforced soft ground and reinforced by floating bottom ash columns. For treated
cases, bottom ash columns of 25 mm diameter and 150 mm length were installed in the soft ground
with an area replacement ratio of 13%. The experimental test results revealed that the inclusion of
floating bottom ash columns in the soft soil ground enhances the carrying capacity and accelerates
the settlement compared to untreated ground.
Keywords: Foundation; Granular column; Ground improvement; Clay soil; Coal ash
systems regarding classical set-up processes. Based on the major contributors behind such performances: the shape effect and the electrical
discharge installation, a case study is analyzed in view of highlighting that the coupling of these two components leads to a reasonable
estimation of RIT shaft capacity with reference to in situ loading tests. A related design chart estimating the contribution of the shape effect in
the increase of the shaft capacity had been drawn and a mean power law was proposed through a parametric study on the adhesion factor.