Videos by Bouassida Mounir
The video comprises two exercises related to soil identification, stress calculation et settlemen... more The video comprises two exercises related to soil identification, stress calculation et settlement estimations for different current soil mechnics applications: overburden stresses, dewatering, excavation et surcharge. The video is in French language. 2 views
Papers by Bouassida Mounir
Proceedings 18th Regional African Conference on Soil Mechanics and Geotechnical Engineering, 2024
This paper outlines three computational procedures embodied in the software
GeoSpring 1.0 elabor... more This paper outlines three computational procedures embodied in the software
GeoSpring 1.0 elaborated for the design of foundations. The first computational procedure deals
with the settlement calculation of a single RIT pile. The second procedure addresses the settlement
induced by a trapezoidal embankment along its base. The third procedure highlights the
optimization of the reinforcement by rigid inclusions under a raft foundation. The third procedure
explains the interaction, in terms of settlement, of a group of footings.
Studies in Engineering and Exact Solutions, 2024
This study investigates the performance of sand compaction piles (SCPs) using
numerical modeling... more This study investigates the performance of sand compaction piles (SCPs) using
numerical modeling techniques. Initially, the widely used composite cell approach
was employed to simulate the behavior of SCPs within a finite element study
(FEM). However, a comparison of the FEM-predicted vertical displacements with
in-situ measurements revealed significant underestimations, highlighting the
limitations of this simplified approach. To address these limitations, a more
advanced Lagrangian finite-difference approach, implemented using the FLAC3D
code, was developed. This model was calibrated against the analytical Greenwood
solution, demonstrating strong agreement of predicted vertical displacements. The
numerical simulations enabled a better highlight of improvement in soil settlement
behavior after SCPs installation, attributed to increased soil stiffness and shear
strength parameters. The study delved into various aspects of SCP behavior,
including lateral deformation, stress distribution, and the effects of pile length,
material properties, and loading conditions. The results provide valuable insights
into the mechanisms underlying the performance of SCPs and the factors
influencing their effectiveness in improving soil resistance and reducing settlement.
By understanding these mechanisms, engineers can optimize the design and
implementation of SCPs in geotechnical engineering applications.
Soils and Foundations, 2004
Soils & Foundations, 2004
Geomechanics and Geoengineering, an Int. Journal
Stone column installation is commonly employed to prevent liquefaction. Stone columns mitigate li... more Stone column installation is commonly employed to prevent liquefaction. Stone columns mitigate liquefaction by means of mainly three mechanisms which are drainage, stiffening and densification. A factor of safety against liquefaction FSis used to quantify liquefaction potential. The aim of this study was to assess the efficiency of stone columns as a liquefaction remediation based on twenty four case studies. In these cases, SPT and CPT tests were recorded before and after stone columns installation. It was found that the installation of stone columns considerably increased soil density mainly in clean to slightly silty sand. The average rate of increase in the penetration resistance N 1;60;cs and q c1Ncs were about 31.13% to 69.29% and 57.10% to 318.28%, respectively. Furthermore, the cyclic shear stress ratio of reinforced soil can be reduced by 13.5% to 77.5% due to the stiffening improvement of stone columns. Densification and stiffening mechanisms have been investigated through several approaches. Their individual and combined effects have been analysed. Comparative results indicate that considering the densification and stiffening effects in liquefaction analyses improved considerably the performance of stone columns.
Innovative infrastructure solutions, Jul 6, 2024
This paper aims at presenting a numerical study of the behaviour of Tunis soft soil improved by v... more This paper aims at presenting 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) initially extracted from the centre of Tunis city at 35 m of depth. Three consolidation tests were carried out in a cell of 126mm 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 (p v =100 kPa) were performed. The third test comprised a vacuum consolidation test combined with the preload (p v =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 k h of TSS. Then, by comparing the numerical results to the recorded data in laboratory, it has been verified that the numerical predicted settlements are higher than those measured during the performed laboratory tests. Further, numerical results confirmed that when the coefficient k h 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.
International journal of geomechanics, May 1, 2024
This paper studies the design of foundations built on thick compressible soft soil layers that ar... more This paper studies the design of foundations built on thick compressible soft soil layers that are reinforced by floating columns. Based on a recent methodology, the suggested design combines the bearing capacity and settlement verifications to provide an optimized improvement area ratio (IAR). Then, an optimized length for the floating columns is obtained by introducing the admissible long-term settlement of the unreinforced compressible sublayers and assuming that the total short-term settlement vanishes at the end of project construction. This paper focuses on the variation in the consolidation settlement of the unreinforced compressible sublayer versus the length of the floating columns. The discussion of this design methodology highlights the feasibility of a potential reinforcement solution when producing a cost-effective design, which assures an optimized IAR within the reinforced upper layer and an optimized length for the floating columns. Using typical case history data, a parametric study showed that reinforcement with end-bearing columns is not required to control the admissible long-term settlement. Instead, the suggested design method enables the determination of the optimized length of the floating columns, which satisfies the admissible residual settlement and consolidation time. The comparison between the proposed results and numerical predictions by Plaxis 2D shows good agreement, which confirms the feasibility of an optimized length for floating columns and avoids the systematic adoption of end-bearing reinforcement in columns.
Deleted Journal, Nov 7, 2022
Innovative Infrastructure Solutions, 2024
This paper aims at presenting a numerical study of the behaviour of Tunis soft soil improved by v... more This paper aims at presenting 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) initially extracted from the centre of Tunis city at 35 m of depth. Three consolidation tests were carried out in a cell of 126mm 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 (p v =100 kPa) were performed. The third test comprised a vacuum consolidation test combined with the preload (p v =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 k h of TSS. Then, by comparing the numerical results to the recorded data in laboratory, it has been verified that the numerical predicted settlements are higher than those measured during the performed laboratory tests. Further, numerical results confirmed that when the coefficient k h 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.
Journal of Geomechanics and Geo-Engineering, 2023
This paper presents a detailed analysis of three Tunisian ground improvement case histories. The ... more This paper presents a detailed analysis of three Tunisian ground improvement case histories. The first case addresses the cause of disorders that seriously affected the stability of an oil tank, initially built on a superficial soft clay layer improved by sand piles. Due to the underestimated length of sand piles, the oil tank operations stopped after non-admissible consolidation differential settlement. Retrofit solution using micropiles' reinforcement revealed quite satisfactory to restart the functioning of the oil tank after fifteen years. The second case deals with the reinforcement of compressible silt sand layer by floating stone columns to reduce the long-term differential settlement of a gas storage facility. Recorded measurements during the follow-up of stage construction of the storage facility permitted the assessment of numerical predictions of the settlement of reinforced soil. The third case studies the stability of access ramps of an interchange in Tunis Centre. Built numerical plane strain modelling helped for the prediction of the behaviour of embankment access on improved Tunis soft soil by geodrains. Based on recorded settlements and horizontal displacements, followed the validation of computed consolidation settlement. Adoption of suitable parameters of two constitutive models of the behaviour of Tunis soft clay is discussed.
Geomechanics and Geoengineering, 2016
ABSTRACT This paper addresses the installation effects of stone columns in soft soils. Focus is m... more ABSTRACT This paper addresses the installation effects of stone columns in soft soils. Focus is made on the lateral expansion of stone material using the vibro displacement and substitution techniques by means of numerical simulations. The behaviour of reinforced soil after stone column installation is investigated to show how the properties of soft soils can be improved prior to final loading. The effect of such an improvement on the prediction of reinforced soil settlement is evaluated. The axisymmetric unit cell model (UCM) served for the comparison between numerical predictions made by the Mohr-Coulomb and hardening soil constitutive laws adopted for the soft soil. An equivalent group of end bearing columns model was investigated in the axisymmetric condition to predict the settlement of reinforced soil by adopting the Mohr-Coulomb constitutive model for soft clay. The reduction of settlements predicted by the unit cell and group of columns models, due the improvement of the Young’s modulus of soft clay, were compared. It is concluded that a significant reduction of settlement is expected when the group of columns model is considered.
International Journal of Geomechanics , 2024
This paper studies the design of foundations built on thick compressible soft soil layers that ar... more This paper studies the design of foundations built on thick compressible soft soil layers that are reinforced by floating columns.
Based on a recent methodology, the suggested design combines the bearing capacity and settlement verifications to provide an optimized
improvement area ratio (IAR). Then, an optimized length for the floating columns is obtained by introducing the admissible long-term settlement of the unreinforced compressible sublayers and assuming that the total short-term settlement vanishes at the end of project construction. This paper focuses on the variation in the consolidation settlement of the unreinforced compressible sublayer versus the length of the
floating columns. The discussion of this design methodology highlights the feasibility of a potential reinforcement solution when producing a
cost-effective design, which assures an optimized IAR within the reinforced upper layer and an optimized length for the floating columns.
Using typical case history data, a parametric study showed that reinforcement with end-bearing columns is not required to control the admissible long-term settlement. Instead, the suggested design method enables the determination of the optimized length of the floating columns, which satisfies the admissible residual settlement and consolidation time. The comparison between the proposed results and
numerical predictions by Plaxis 2D shows good agreement, which confirms the feasibility of an optimized length for floating columns
and avoids the systematic adoption of end-bearing reinforcement in columns.
Proceedings of the Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017), 2017
This manuscript presents the use of recharge impulse technology (RIT) in pile foundations setup t... more This manuscript presents the use of recharge impulse technology (RIT) in pile foundations setup through a case study. More precisely, it discusses the performance brought by such a technique in terms of increasing the bearing capacity of deep foundation systems comparing to classical setup processes. First, a historical overview about the technology and its contribution in referenced projects is presented. Then, a discussion about the major components behind the performance of such a technique, in pile foundation setup , comparing to bored and driven piles is highlighted. The final section illustrates the use of RIT through a case study.
Geo-China 2016, 2016
This paper aims to assess the numerical predictions of settlement reduction of compressible soil ... more This paper aims to assess the numerical predictions of settlement reduction of compressible soil reinforced by rigid inclusion with experimental results obtained from experiments conducted in calibration chamber. Loading tests carried out in calibration chamber are simulated in axisymmetric condition. Numerical computation focused on settlement variation both for the unreinforced soil and reinforced soil. It was found the main component of settlement of reinforced soil is quickly stabilized after loading compared to the settlement of unreinforced soil. Further, the role of efficiency has been highlighted in showing the benefit of rigid inclusion technique.
The present paper studies the use of stone columns as a means of mitigating liquefaction potentia... more The present paper studies the use of stone columns as a means of mitigating liquefaction potential. A numerical model using the 2D finite difference code FLAC is developed and validated with published experimental results from literature to simulate the shaking table test. The liquefaction potential of silty sand layer that was improved with stone columns was evaluated in terms of the maximum pore water pressure ratio \( r_{u} \) which is usually defined as the ratio of pore water pressure to the initial vertical effective stress in the soil. Soil liquefaction potential has often been defined when \( r_{u} \) reaches 1.0. Numerical analyses showed that the liquefaction potential decreased after stone columns reinforcement. Parametric analyses were performed to investigate the effect of the excitation frequency and amplitude and the effect of stone columns installation process on liquefaction potential.
Il s'agit du livre de mécanique des sols notions de base de mécanique des sols
Journal of Geotechnical and Geoenvironmental Engineering, 2017
AbstractThe installation of stone columns is widely adopted to prevent liquefaction. The main imp... more AbstractThe installation of stone columns is widely adopted to prevent liquefaction. The main improvement mechanisms of stone columns as a liquefaction countermeasure are drainage, stiffening, and ...
Advances in Research in Geosciences, Geotechnical Engineering, and Environmental Scienc, 2023
Expansive soils currently pose serious pathologies and significant damages to lightweight constr... more Expansive soils currently pose serious pathologies and significant damages to lightweight constructions. Geologically, expansive soils exist in most
regions of the world. In geotechnical engineering, this soil category deserves more
attention from geotechnical engineering researchers. The constructions are threatened because the volume variation in expansive soils is tributary of the variation
of the water content. Furthermore, repairing solutions of affected constructions is
of a high cost. So far, attention made by investigators, focused first, on the occurrence of the swelling phenomenon, and, second, the efficient methods to quantify
the swelling pressure. The key issue, in practice, is to mitigate the swelling phenomenon of foundations built on expansive soils. Among the proposed solutions,
chemical treatments and improvement solutions, like the use of granular materials
revealed successful. This study aims to develop a method to identify if a clayey soil
is expansive or non-expansive through analyzing consolidation test results. The
proposed method considers the swelling index (Cs) and the compression index
(Cc). The ratio “Cc/Cs” appears a good indicator, by identified thresholds values
to make the difference between expansive and non-expansive clay ones. After, the
proposed method of identification, when the Cc/Cs ratio exceeds 15, the swelling
pressure vanishes. In turn, when Cc/Cs ratio is lower than 10, the swelling pressure
increases as this ratio decreases.
Keywords: Characterization · Disaster · Expansive soils · Oedometer test ·
Replacing steel reinforcements with the inclusions of Glass Fiber Reinforced Polymer (GFRP) is on... more Replacing steel reinforcements with the inclusions of Glass Fiber Reinforced Polymer (GFRP) is one of the most promising solutions not only to overcome corrosion problems, but also to improve soil nail durability as a tool of slopes stabilization and retaining excavations. The present study provides an insightful knowledge regarding the pull-out behaviour of a GFRP nail observed in laboratory from a pull-out test. It is a parametric study, which includes the influence of nail dimensions, the overburden pressure, and the degree of saturation, essentially on the pull-out load of the GFRP nail. Using an experimental working method, based on a full factorial design, the study reveals that the influence of nail dimensions and the overburden pressure on the pull-out load are more significant than that of the degree of saturation. Moreover, the experimental results show that the pull-out behaviour of the GFRP reinforcement is different from the ribbed steel reinforcement, subjected to the same testing condition. The differences between the Young's modulus, the interface properties, and the surface roughness of the bar exhibit the main influence factors.
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Videos by Bouassida Mounir
Papers by Bouassida Mounir
GeoSpring 1.0 elaborated for the design of foundations. The first computational procedure deals
with the settlement calculation of a single RIT pile. The second procedure addresses the settlement
induced by a trapezoidal embankment along its base. The third procedure highlights the
optimization of the reinforcement by rigid inclusions under a raft foundation. The third procedure
explains the interaction, in terms of settlement, of a group of footings.
numerical modeling techniques. Initially, the widely used composite cell approach
was employed to simulate the behavior of SCPs within a finite element study
(FEM). However, a comparison of the FEM-predicted vertical displacements with
in-situ measurements revealed significant underestimations, highlighting the
limitations of this simplified approach. To address these limitations, a more
advanced Lagrangian finite-difference approach, implemented using the FLAC3D
code, was developed. This model was calibrated against the analytical Greenwood
solution, demonstrating strong agreement of predicted vertical displacements. The
numerical simulations enabled a better highlight of improvement in soil settlement
behavior after SCPs installation, attributed to increased soil stiffness and shear
strength parameters. The study delved into various aspects of SCP behavior,
including lateral deformation, stress distribution, and the effects of pile length,
material properties, and loading conditions. The results provide valuable insights
into the mechanisms underlying the performance of SCPs and the factors
influencing their effectiveness in improving soil resistance and reducing settlement.
By understanding these mechanisms, engineers can optimize the design and
implementation of SCPs in geotechnical engineering applications.
Based on a recent methodology, the suggested design combines the bearing capacity and settlement verifications to provide an optimized
improvement area ratio (IAR). Then, an optimized length for the floating columns is obtained by introducing the admissible long-term settlement of the unreinforced compressible sublayers and assuming that the total short-term settlement vanishes at the end of project construction. This paper focuses on the variation in the consolidation settlement of the unreinforced compressible sublayer versus the length of the
floating columns. The discussion of this design methodology highlights the feasibility of a potential reinforcement solution when producing a
cost-effective design, which assures an optimized IAR within the reinforced upper layer and an optimized length for the floating columns.
Using typical case history data, a parametric study showed that reinforcement with end-bearing columns is not required to control the admissible long-term settlement. Instead, the suggested design method enables the determination of the optimized length of the floating columns, which satisfies the admissible residual settlement and consolidation time. The comparison between the proposed results and
numerical predictions by Plaxis 2D shows good agreement, which confirms the feasibility of an optimized length for floating columns
and avoids the systematic adoption of end-bearing reinforcement in columns.
regions of the world. In geotechnical engineering, this soil category deserves more
attention from geotechnical engineering researchers. The constructions are threatened because the volume variation in expansive soils is tributary of the variation
of the water content. Furthermore, repairing solutions of affected constructions is
of a high cost. So far, attention made by investigators, focused first, on the occurrence of the swelling phenomenon, and, second, the efficient methods to quantify
the swelling pressure. The key issue, in practice, is to mitigate the swelling phenomenon of foundations built on expansive soils. Among the proposed solutions,
chemical treatments and improvement solutions, like the use of granular materials
revealed successful. This study aims to develop a method to identify if a clayey soil
is expansive or non-expansive through analyzing consolidation test results. The
proposed method considers the swelling index (Cs) and the compression index
(Cc). The ratio “Cc/Cs” appears a good indicator, by identified thresholds values
to make the difference between expansive and non-expansive clay ones. After, the
proposed method of identification, when the Cc/Cs ratio exceeds 15, the swelling
pressure vanishes. In turn, when Cc/Cs ratio is lower than 10, the swelling pressure
increases as this ratio decreases.
Keywords: Characterization · Disaster · Expansive soils · Oedometer test ·
GeoSpring 1.0 elaborated for the design of foundations. The first computational procedure deals
with the settlement calculation of a single RIT pile. The second procedure addresses the settlement
induced by a trapezoidal embankment along its base. The third procedure highlights the
optimization of the reinforcement by rigid inclusions under a raft foundation. The third procedure
explains the interaction, in terms of settlement, of a group of footings.
numerical modeling techniques. Initially, the widely used composite cell approach
was employed to simulate the behavior of SCPs within a finite element study
(FEM). However, a comparison of the FEM-predicted vertical displacements with
in-situ measurements revealed significant underestimations, highlighting the
limitations of this simplified approach. To address these limitations, a more
advanced Lagrangian finite-difference approach, implemented using the FLAC3D
code, was developed. This model was calibrated against the analytical Greenwood
solution, demonstrating strong agreement of predicted vertical displacements. The
numerical simulations enabled a better highlight of improvement in soil settlement
behavior after SCPs installation, attributed to increased soil stiffness and shear
strength parameters. The study delved into various aspects of SCP behavior,
including lateral deformation, stress distribution, and the effects of pile length,
material properties, and loading conditions. The results provide valuable insights
into the mechanisms underlying the performance of SCPs and the factors
influencing their effectiveness in improving soil resistance and reducing settlement.
By understanding these mechanisms, engineers can optimize the design and
implementation of SCPs in geotechnical engineering applications.
Based on a recent methodology, the suggested design combines the bearing capacity and settlement verifications to provide an optimized
improvement area ratio (IAR). Then, an optimized length for the floating columns is obtained by introducing the admissible long-term settlement of the unreinforced compressible sublayers and assuming that the total short-term settlement vanishes at the end of project construction. This paper focuses on the variation in the consolidation settlement of the unreinforced compressible sublayer versus the length of the
floating columns. The discussion of this design methodology highlights the feasibility of a potential reinforcement solution when producing a
cost-effective design, which assures an optimized IAR within the reinforced upper layer and an optimized length for the floating columns.
Using typical case history data, a parametric study showed that reinforcement with end-bearing columns is not required to control the admissible long-term settlement. Instead, the suggested design method enables the determination of the optimized length of the floating columns, which satisfies the admissible residual settlement and consolidation time. The comparison between the proposed results and
numerical predictions by Plaxis 2D shows good agreement, which confirms the feasibility of an optimized length for floating columns
and avoids the systematic adoption of end-bearing reinforcement in columns.
regions of the world. In geotechnical engineering, this soil category deserves more
attention from geotechnical engineering researchers. The constructions are threatened because the volume variation in expansive soils is tributary of the variation
of the water content. Furthermore, repairing solutions of affected constructions is
of a high cost. So far, attention made by investigators, focused first, on the occurrence of the swelling phenomenon, and, second, the efficient methods to quantify
the swelling pressure. The key issue, in practice, is to mitigate the swelling phenomenon of foundations built on expansive soils. Among the proposed solutions,
chemical treatments and improvement solutions, like the use of granular materials
revealed successful. This study aims to develop a method to identify if a clayey soil
is expansive or non-expansive through analyzing consolidation test results. The
proposed method considers the swelling index (Cs) and the compression index
(Cc). The ratio “Cc/Cs” appears a good indicator, by identified thresholds values
to make the difference between expansive and non-expansive clay ones. After, the
proposed method of identification, when the Cc/Cs ratio exceeds 15, the swelling
pressure vanishes. In turn, when Cc/Cs ratio is lower than 10, the swelling pressure
increases as this ratio decreases.
Keywords: Characterization · Disaster · Expansive soils · Oedometer test ·