Bouassida Mounir
M. Bouassida is a professor of civil engineering at the National EngineeringSchool of Tunis (ENIT) of the Universityof Tunis El Manar where he earned his B.S., M.S., Ph.D., and doctorate of sciences diplomas, all in civil engineering. He is the director of the Research Laboratory in Geotechnical Engineering and has supervised 22 Ph.D. and 31 master of science graduates. His research focuses on soil improvement techniques and behavior of soft clays. Dr. Bouassida is the (co)author of 87 papers in refereed international journals
less
Uploads
Videos
Papers
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 ·
research conducted to determine the failure load applied at the top of excavations in sandy soils
during the construction of deep digs without the use of retaining systems. An experimental program
was performed to measure the failure load of ten laboratory-compacted sand slope models that
were constructed using different slope angle values and different locations for the applied loading,
which consisted of an imposed uniform rate of vertical displacement at the top of the slope. Then,
a three-dimensional (3D) numerical model of the laboratory tests was developed to simulate the
observed behavior during the experiments by the Plaxis 3D code. The Mohr–Coulomb (MC) and
hardening soil (HS) models were used to describe the behavior of the compacted sand. The results
showed that the 3D numerical simulations based on the MC model were able to predict the measured
failure load within a relative difference of less than 11% for nine tested slope models, while the HS
model was better in predicting the measured failure load (a relative difference of 3.5%) for only one
experimental setup when the slope angle was equal to 35◦
. Furthermore, analytical prediction of
the failure load using the yield design theory (YDT) permitted the validation of the log-spiral curve
describing the observed failure surface for the tested sand slope models.
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 ·
research conducted to determine the failure load applied at the top of excavations in sandy soils
during the construction of deep digs without the use of retaining systems. An experimental program
was performed to measure the failure load of ten laboratory-compacted sand slope models that
were constructed using different slope angle values and different locations for the applied loading,
which consisted of an imposed uniform rate of vertical displacement at the top of the slope. Then,
a three-dimensional (3D) numerical model of the laboratory tests was developed to simulate the
observed behavior during the experiments by the Plaxis 3D code. The Mohr–Coulomb (MC) and
hardening soil (HS) models were used to describe the behavior of the compacted sand. The results
showed that the 3D numerical simulations based on the MC model were able to predict the measured
failure load within a relative difference of less than 11% for nine tested slope models, while the HS
model was better in predicting the measured failure load (a relative difference of 3.5%) for only one
experimental setup when the slope angle was equal to 35◦
. Furthermore, analytical prediction of
the failure load using the yield design theory (YDT) permitted the validation of the log-spiral curve
describing the observed failure surface for the tested sand slope models.
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.
Keywords: Stone column, Remolded kaolin, Cavity expansion, Improved
characteristics