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Resilient Modulus of Unbound Aggregate base Courses from Senegal (West Africa)

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Open Journal of Civil Engineering 2011年第1期1卷 1-6页

作者： makhaly ba Meissa Fall Fatou Samb Déthié Sarr Mapathé Ndiaye 不详

This paper presents the results of research conducted to investigate the Resilient Modulus (Mr) of unbound aggregates used as pavement layer in Senegal (West Africa) as well as the effect of water content and density on the Resilient Modulus of the materials tested. Four different aggregates was collected from different sites within Senegal and then subjected to repeated load triaxial tests. Test results showed that the bandia limestone is around 44% stiffer than the basalt, and 71% to 104% stiffer that the Black and the Red quartzites (GNB and GRB). The basalt is 21% to 43% stiffer than the GNB and the GRB. basalt specimens compacted at Wopt– 2% were 30% stiffer than basalt specimens compacted at Wopt and 40% stiffer than those com- pacted at Wopt+ 2%. The Summary Resilient Modulus (SRM) at Wopt– 2% is 22% higher than SRM at Wopt and 35% higher than SRM at Wopt+ 2% for the GRB and the GNB. The SRM at Wopt– 2% is 30% higher than SRM at Wopt and 40% higher than SRM at Wopt+ 2%, for the basalt. For the bandia limestone, the SRM at Wopt– 2% is 81% higher than SRM at Wopt and 126% higher than SRM at Wopt+ 2%. Results show also that the Resilient Modulus increases around 25% when relative density increases from 77% to 119% and the variation is more significant at high stress states than at low stress state. Results of statistical analysis and coefficients of determination (R2) showed that the Uzan and NCHRP models are more suitable to predict the Resilient Modulus of the aggregates tested.

关键词： Resilient Modulus Summary Resilient Modulus Quartzite basalt bandia Limestone Un-bound Aggregates

Influence of the Soil-Structure Interaction in the Behavior of Mat Foundation

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Open Journal of Civil Engineering 2014年第1期4卷 71-83页

作者： Oustasse Abdoulaye Sall Meissa Fall Yves Berthaud makhaly ba Mapathé Ndiaye Département of Génie Civil UFR SI-Université de Thiès Thiès Sénégal Université Pierre et Marie Curie Paris France

This article focuses on the study of the behavior of a soil mass under a plate subjected to a uniformly distributed load. The aim of this paper is to highlight the soil-structure interaction with a linear variation of the mechanical properties of the soil with the depth. The theory of plates and the soil-structure interaction has allowed reaching the general equation of the problem which depends on both the mechanical properties of the concrete and the subgrade. This study shows that the linearity of the elastic modulus of subgrade leads to larger displacements when this modulus is assumed to be constant in the soil mass. It also shows that the Poisson’s ratio of soil and mechanical properties of the concrete have an insignificant influence on the displacements. This analysis also shows that the points in the upper half-thickness of soil are the most sensitive to the parameters of the model.

关键词： Mat Foundation Plate Theory Soil-Structure Interaction Mechanical Properties

Effect of Water Content and Grains Size Distribution on the Characteristic Resilient Young’s Modulus (<i>E<sub>c</sub></i>) Obtained Using Anisotropic Boyce Model on Gravelly Lateritic Soils from Tropical Africa (Burkina Faso and Senegal)

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Open Journal of Civil Engineering 2021年第1期11卷 134-152页

作者： Bibalo Ida Josiane Ki makhaly ba Rokhaya Gueye Pierre Hornych Ali Sana Laboratoire de Mécanique et Modélisation (L2M) UFR Sciences de l’Ingénieur Université de Thiès Thiès Sénégal

This research was carried out to determine the rheological parameters of lateritic soils in order to contribute to the improvement of the technical documents used for pavement design in tropical Africa. The study is based on the loading repeated of cyclic triaxial tests (LRT) performed at University Gustave Eiffel (formerly Institut Français des Sciences et Technologies des Transports de l’Aménagement et des Réseaux (IFSTTAR)) in Nantes with the application of the European standard EN 13286-7: 2004 [1]. The tests were performed at constant confinement stress and using the stepwise method to determine the resilient axial () and radial () deformation as a function of the axial and radial stresses. Four gravel lateritic soils from different sites selected in Burkina Faso and Senegal were the subject of this research for the triaxial tests. These materials have a maximum diameter of 20 mm a

关键词： Lateritic Soil Cyclic Triaxial with Repeated Loading (LRT) Characteristic Resilient Young’s Modulus Anisotropic Boyce Model Water Content Grains Size Distribution

Relative Dielectric Permittivity Variations during Compaction as a Mean of Compaction Quality Control: Case Study on Laterite Samples from Senegal

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International Journal of Geosciences 2023年第2期14卷 238-250页

作者： Mapathé Ndiaye makhaly ba Teophile Kiendrebeogo Linda E. Gaffo Foudjo Laboratoire de Mécanique et de Modélisation Université de Thiès Sénégal

This study explores an alternative to the classical use of direct methods, as water content and dry density measurements, for compaction quality control. For this purpose, the dielectric properties of lateritic materials are determined by radar method and are compared with the permittivity determined from the Topp formula and from the CRIM model. This approach allowed to establish a relationship between the geotechnical properties determined during compaction such as dry density, water content or porosity with dielectric permittivity. The obtained results made it possible to determine an optimum dielectric permittivity corresponding to the optimum dry density and the optimum water content that could be used for non-destructive in situ compaction testing. Such an approach should improve the implementation and effectiveness of in situ compaction quality control of geotechnical infrastructures.

关键词： Laterite Proctor Water Content Dry Density Dielectric Permittivity

Soil Subgrade’s Characterization and Classification of Thies (Senegal, West Africa) on a Radius of 2.5 Kilometers along Five Roads

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Geomaterials 2016年第1期6卷 1-17页

作者： E.H.B.M. Niakhate Séni Tamba makhaly ba Adama Dione Issa Ndoye Laboratoire de Mécanique et Modélisation-UFR Sciences de l’Ingénieur Université de Thies Thies Sénégal Ecole Polytechnique de Thies (EPT/Thies) Thies Sénégal

This article explains the results of a study conducted on the characterizations of subgrade soils in the region of Thies. The road platforms are mainly composed of a background soil, which is generally overlapped by a surface layer that plays two roles. Firstly, it protects the soil structure, ensures the leveling, and facilitates the movement of vehicles. Secondly, it brings harmony in the mechanistic characteristics of the materials that compose the soil while improving the long-term life force. The methodology consisted in taking samples of subgrade soil along the roads all over the region of Thies in a 5 km diameter span. The identification tests allowed the Thies-Tivaoune, Thies-Khombole and Thies-Noto axes are characterized by tight sands, poorly graded size. While Thies Pout-axis is characteristic of severe solid particle size and spread well graded and serious to spread and well graded particle size. Finally the Thies-Montrolland axis is characterized by severe to very tight particle size and graduated to spread and serious and well graded particle size. The specific gravity values found Proctor test shows the presence of sand, sandy laterite and laterite. In the target area, polished soils of the A-3 type according to the AASHTO classification system are the most represented with 60%, followed by the A-2-6 type 25%, and the A-2-4 type with 9%, which are typical of gravel, clay, and silty sands. Soils of the A-1-b type (2%) typical of roc fragments, sands and clay are also represented. Polished sands of the A-3 type have a better efficiency on road infrastructures than other types of soil listed above. Finally, we’ve also noted the presence of soils of the A-2-7 and A-4 types with the low percentage of 2%. Subgrade soils of class S4 are the most represented with 58%, followed by those of class S5 with 42%. Samples of the Thies-Montrolland road have a claylike plasticity (CL or CH group), while those of the Thies-Pout road belong to the ML or OL and CL or OL

关键词： Subgrade Soil Mechanistic Pavement Design Arc GIS AASHTO CBR Resilient Modulus

Influence of Mechanical Properties of Concrete and Soil on Solicitations of Mat Foundation

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Open Journal of Civil Engineering 2015年第2期5卷 249-260页

作者： Oustasse Abdoulaye Sall makhaly ba Mapathé Ndiaye Daouda Sangare Mathioro Fall Alassane Thiam Dé partement de Gé nie Civil UFR SI-Universit&eacute de Thiè s Thi&egrave s S&eacute né gal Dé partement de Mathé matiques UFR SAT-Universit&eacute Gaston Berger Saint Louis S&eacute né gal

This work studies the influence of mechanical and geometrical characteristics of the concrete and the soil on the stresses in a mat foundation. In this study, the soil-structure interaction is modeled by two parameters, the modulus of subgrade vertical reaction (k) and the modulus of subgrade horizontal reaction (2T). These two parameters are dependent on the geometrical and mechanical characteristics of the system. Results of this study show a sensitivity of solicitations to variations of geometrical and mechanical characteristics of the model. Although solicitations in the plate are sensitive to mechanical properties of concrete, these solicitations are strongly influenced by the mechanical and geometrical characteristics of the soil mass. However, it should be noted that the influence of Eb is denoted in the center of the plate whereas the Es feels almost in the same manner over the entire extent of the plate. This study also shows that for the same load cases, the values of the torsion moment and shear stress are not significant those of bending moments and normal stresses, respectively.

关键词： Plate Soil-Structure Interaction Mechanical Properties Modeling Solicitations

Grain Size Influence on the Compaction Aptitude and the Bearing Strength of the Gravel Lateritic Soils

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Geomaterials 2018年第4期8卷 63-76页

作者： baye Oumar Diop Ignace Gbaguidi Papa Goumbo Lo Aminata Cisse Seynabou Sène makhaly ba cole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Institut des Sciences de la Terre Faculté des Sciences et Techniques Université Cheikh Anta Diop Dakar Senegal Centre Expérimental de Recherches et d’études pour l’équipement (CEREEQ)1 Dakar Senegal AGEROUTE-Sénégal Fann Résidence Dakar Senegal UFR Sciences de l’Ingénieur Université de Thiès Thiès Senegal

This study is carried out to appreciate the coarse elements influence of the gravel lateritic soils on the pavement behavior. The material involves not only the 0/20 mm granular particles considered in the specifications and on the laboratory tests, but also all of the material that is actually used in the construction sites. Geotechnical characterization was leaned on five differentiated granular classes of 0/20;0/25;0/31.5;0/40 and 0/63 mm diameters. The sample of 0/40 mm gets the best compaction aptitude, while that of 0/31.5 mm reaches the greatest bearing strength and a good Optimum Moisture Content. According to the requirements and its bearing strengths, the material is usable up to subbase layer and its behavior depends on the grain size.

关键词： Granular Class Bearing Strength Optimum Modified Proctor (OMP) Gravel Lateritic Soils Pavement

Characterization and Modeling of Reinforced Earth Structures

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Open Journal of Applied Sciences 2024年第10期14卷 2943-2954页

作者： Tchamiè David Midikizi Oustasse Abdoulaye Sall Déthié Sarr Cheikh Ibrahima Tine Ndeye Seynabou Ndiaye makhaly ba Department of Civil Engineering UFR SI-University of This This Senegal Department of Geotechnics UFR SI-University of This This Senegal

The aim of this study is to characterize soil/reinforcement interaction in reinforced earth structures. The study showed that the internal behavior of this type of structure depends on a number of factors, including the engineering backfill, the reinforcement and the soil/reinforcement interaction. The study also showed that the soil-reinforcement interaction phenomenon is a fairly complex mechanism that depends on the applied load, the geometry of the structure, the characteristics of the soil and a set of parameters characterizing the nailing: density, number and length of reinforcements, inclination of the reinforcements in relation to the sliding surface, mechanical characteristics of the reinforcements and, in particular, the relative stiffness of the reinforcements and the soil. The results showed that the tensile forces developed in the reinforcement are not entirely reversible, and that the soil at the interface undergoes permanent deformation, leading to the appearance of irreversible tensile forces in the reinforcement.

关键词： Reinforced Earth Structures Modeling Earth/Reinforcement Interaction

Geomechanical Characterization of Sandstones Cliffs of Segou (Senegal, West Africa) in the Madina Kouta basin

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International Journal of Geosciences 2012年第1期3卷 166-174页

作者： Déthié Sarr Meissa Fall Papa Malick Ngom Mapathé Ndiaye Cheikh H. Kane makhaly ba Laboratoire de Mécanique et Modélisation-UFR Sciences de l’Ingénieur Université de Thiès Thiès Sénégal

This work presents the behavior of Segou sandstones in the laboratory and in the field conditions. Four types of sandstone are collected in the northern part of the Madina Kouta basin (eastern Senegal). These types of specimens are the white sandstones, the red sandstones, the purple sandstones and the sandstones with intercalation of pelites. Uniaxial tests are carried out on these specimens of sandstones. The Young Moduli (E) and the Uniaxial Compression Strengths (Rc) are higher for the white sandstone. Values of the mechanical parameters decrease slightly for red sandstones due to an increase of the amount of pelites in the composition of the rock. Decrease of mechanical parameters is more important for the purple facies due to an important network of fractures. The facies with weaker characteristics corresponds to the sandstones with intercalation of pelites. This is due to the soft nature of the pelites. The slope stability of the Cliff sides depends also on to these characteristics.

关键词： Unconfined Compression Test-Uniaxial Compression Strength (UCT Rc) JRC (Joint Roughness Coefficient) Young Modulus (E) Roughness Segou-Madina Kouta basin Discontinuities Dihedral Slope Cliff