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Resilient Modulus of Compacted Lateritic Soils from Senegal at OPM Conditions

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Geomaterials 2013年第4期3卷 165-171页

作者： Fatou Samb meissa fall Yves Berthaud Makhaly Ba Laboratoire d’ Alembert—Université Pierre et Marie Curie Paris France Laboratoire de Mécanique et Modélisation—UFR Sciences de l’ Ingénieur Université de Thiès Thiès Sénégal

Repeated load triaxial tests were performed on five compacted gravel lateritic soils collected from different locations in Senegal: Sébikotane, Dougar, Pa Lo, Mont-Rolland and Ngoundiane. The study revealed that resilient modulus decreases with the increase of the bulk and deviatoric stress in constant confining pressure. In addition, resilient modulus increases with the percentage of cement for appreciably equal contents of moisture. This effect tends to stop for higher stress. Besides, correlations were made with some models of resilient modulus such as the Uzan-Witczack model (Witczack and Uzan, 1988 [1]) and the National Highway Research Program (NCHRP) model (2004 [2]). The study confirms that both models give very good results with the best correlations being obtained with the Uzan-Witczack model.

关键词： Gravel Lateritic Soils Resilient Modulus Mechanical Behaviour Pavement Cyclic Triaxial Test Mechanistic Design

Evaluation of the Impact of Truck Overloading on Flexible Compacted Gravel Lateritic Soil’s Pavements by FEM with Cast3M<sup>©</sup>

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Geomaterials 2015年第1期5卷 19-24页

作者： Fatou Samb meissa fall Yves Berthaud Farid Bendboudjema Laboratoire de Mécanique et Modélisation UFR Sciences de l’Ingénieur Université de Thiès Thiès Sénégal Sorbonne Universités UPMC Univ Paris 06 UMR 7190 d’Alembert F-75005 Paris France Laboratoire de Mécanique et de Technologie Ecole Normale Supérieure de Cachan Cachan France

Within the framework of a FEM of the nonlinear behavior of lateritic pavement of Senegal, the effect of truck overloading is studied to estimate its impact on the deformability of road pavement on compacted gravel lateritic soils. For that purpose, various loading conditions were tested to measure the impact on the critical response parameters of road pavement design. The implementation of the models was realized with Cast3M©. This study allowed us to point out that the observed variations are linear and would help to plan in advance the impact of axle overloads for a better evaluation within the framework of the mechanistic (M. E.) design of pavements.

关键词： FEM Axle Overload Nonlinear Behavior Gravel Lateritic Soil

Influence of the Elastic Modulus of the Soil and Concrete Foundation on the Displacements of a Mat Foundation

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Open Journal of Civil Engineering 2013年第4期3卷 228-233页

作者： Oustasse Abdoulaye Sall meissa fall Yves Berthaud Makhaly Ba Département Génie Civil UFR SI-Université de Thiès Thiès Sénégal UFR Ingénierie Université Pierre et Marie Curie Paris France

In this paper, we suggest to study the behavior of a mat foundation on subsoil from the plate theory taking into account the soil-structure interaction. The objective is to highlight the soil-structure interaction particularly the influence of the rigidities of the soil and the concrete on the subgrade reaction (k) and the displacements of the mat foundation subjected to vertical loads. From plate theory and the soil-structure interaction, the general equation is reached. This equation depends more on the subgrade properties than the concrete foundation properties. Consequently, the behavior of the mat foundation is more influenced by soil properties than the concrete.

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

A Semi Automated Method for Laminated Sediments Analysis

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International Journal of Geosciences 2012年第1期3卷 206-210页

作者： Mapathe Ndiaye Eric Davaud Daniel Ariztegui meissa fall Laboratoire de Mécanique et Modélisation Université de Thiès Thiès Senegal

We developed a software performing laminae counting, thickness measurements, spectral and wavelet analysis of laminated sediments embedded signal. We validated the software on varved sediments. Varved laminae are automatically counted using an image analysis classification method based on K-Nearest Neighbors (KNN) algorithm. In a next step, the signal corresponding to varved black laminae thickness variation is retrieved. The obtained signal is a good proxy to study the paleoclimatic constraints controlling sedimentation. Finally, the use of spectral and wavelet analysis methods on the variation of black laminae thickness revealed the existence of frequencies and periods which can be linked to known paleoclimatic events.

关键词： Varve Laminated Sediment K-Nearest Neighbor Signal Time-Series Spectral Analysis Wavelet Analysis

Diagnosis Study of the Louga-Ouarack-Ndoyene R31 Regional Road (Senegal)

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Geomaterials 2015年第1期5卷 34-44页

作者： Seybatou Diop meissa fall Adama Dione Moshood N. Tijani Institut des Sciences de la Terre Faculté des Sciences et Techniques Université Cheikh Anta Diop de Dakar Dakar Sénégal Laboratoire de Mécanique et Modélisation UFR Sciences de l’Ingénieur Université of Thiès Thiès Sénégal Department of Geology University of Ibadan Ibadan Nigeria

The degree of structural damage of the Louga-Ouarack-Ndoyene R31 regional road was surveyed using Lacroix deflectographe and geotechnical testing, in order to recommend possible rehabilitation measures aimed at maintaining the high level of service over the projected life span of the road. The data processing and interpretation were essentially based on the French standards and specifications, through which synthetic variables were generated with a qualitative significance?and on the basis of which the extent of repairs and rehabilitation works to be undertaken were suggested. The decision grid thus produced, revealed road structure quality indices of mostly Q3, Q4, and Q5 types for a segment length of 36.954 km (equivalent to some 69.44% of the total road section), which justifies some major reinforcement works. The remaining part of the road section (nearly?30.56% with road quality indices ≤ Q2) is still in acceptable condition, requiring only some?minor maintenance works. The rehabilitation costs were estimated to be of the order of?5,352,000,000 (five billion three hundred fifty-two million) CFA francs, based on local market price conditions.

关键词： Senegal Road Diagnosis Lacroix Deflectograph Deflection Reinforcement Maintenance

Mechanical Behavior of Pillow Lavas in MakoSupergroup: Case of South Mako Hill

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International Journal of Geosciences 2011年第4期2卷 640-647页

作者： Déthié Sarr meissa fall Papa Malick Ngom Mapathé Ndiaye 不详

This work shows the Kédougou-Kéniéba inlier (eastern Senegal) pillow lavas behavior from laboratory to field. Some uniaxial tests are carried out on five types of specimens of pillow lavas. These types of specimens are: macroscopicly healthy rock, fractured rock without filling, fractured rock filled with epidote, chlorite and calcite and rocks with tension crack filled with quartz. The Young moduli and the uniaxial compression strength are good for the healthy rock. The Young moduli fall slightly for facies with horizontal cracks while uniaxial compression strength (Rc) varies slightly. For filled fractured specimens, Rc and Young modulus (E) decrease remarkably. Decreases are most important for cracks filled with epidote, chlorite and calcite than with quartz. That is due to the differences of rigidity between these materials. Also, the slope stability of hillsides in this area depends on to these characteristics.

关键词： Unconfined Compression Test-Uniaxial Compression Strength (UCT Rc) JRC (Joint Roughness Coefficient) Young Modulus (E) Roughness Kédougou-Kéniéba Inlier Linea-ments Discontinuities Dihedral Slope Hillside

New Approach of Geomechanical Properties by Scale Effect and Fractal Analysis in the Kedougou-Kenieba Inlier (Senegal-West Africa)

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Geomaterials 2013年第4期3卷 145-155页

作者： Déthié Sarr meissa fall Papa Malick Ngom Mamadou Gueye Département de Géologie FST-UCAD Université Cheikh Anta Diop de Dakar Dakar Sénégal Institut des Science de la Terre FST-UCAD Université Cheikh Anta Diop de Dakar Dakar Sénégal Laboratoire de Mécanique et Modélisation UFR Sciences de l’ Ingénieur Université de Thiès Thiès Sénégal

This paper shows geometric aspects of rock masses in the Senegalese side of Kédougou-Kéniéba inlier. The studies are done in one part on sedimentary rocks (represented by sandstones) with stratification and on the other part in igneous rocks (represented by basalts). Geometric studies are the fractal configuration and the scale effect. Scale effect is stud- ied by comparing the results of mechanical tests done in the laboratory and on outcrops. For all samples, laboratory pa- rameters are higher than values of field. In this paper, scale effect is characterized by the decrease of mechanical pa- rameters from laboratory samples to field. The scale coefficient is defined and characterizes the relation between me- chanical properties. More importantly, the scale effect is more significant. This scale effect depends largely on the rock anisotropy. The anisotropy depends on the fracturation and the filling. The scale effect takes into account the fracturation, the filling minerals and their diversity which define the complexity of the rock. The anisotropy is complex;the impact of scale effect traduced by an increase of scale coefficient is the highest. Configuration of discontinuities also defines fractal geometry. This fractal aspect appears on the asperities, the spacing and the apertures of discontinuities. The fractal dimension is different from a parameter to another. All these two parameters estimate the stage of fracturation of the rock in a geological system and depend one on another if they are studied in the same element.

关键词： Rock Scale Effect Fractal Kédougou Sedimentary Igneous

A Review and Update of Analytical and Numerical Solutions of the Terzaghi One-Dimensional Consolidation Equation

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Open Journal of Civil Engineering 2014年第3期4卷 274-284页

作者： Cheikhou Ndiaye meissa fall Mapathe Ndiaye Daouda Sangare Abib Tall Laboratoire de Mécanique et Modélisation UFR Sciences de l’Ingénieur Université de Thiès Thiès Sénégal Laboratoire d’Analyse Numérique et d’Informatique UFR Sciences Appliquées et Technologie Université Gaston Berger Saint-Louis Sénégal

Practical resolution of consolidation problems that we often face requires an extensive and solid knowledge of the different parameters highlighted by the Terzaghi one-dimensional consolidation theory. This theory, with its assumptions, leads to a partial differential equation of second order in space and first order in time of pore water pressure. Analytical and numerical resolutions of this equation allow determining the water pressure variation before and after the application of a charge. Numerical modeling has enabled the simulation of the whole results obtained by the two methods of resolution (pressure, degree of consolidation, time factor, among others) to have a physical analysis and a lawful observation that lead to a suitable understanding of the phenomenon of Terzaghi one-dimensional consolidation.

关键词： Pore Pressure Numerical Solution Analytical Solution Modeling Consolidation Time Factor

Effect of Compaction Moisture Content on the Resilient Modulus of Unbound Aggregates from Senegal (West Africa)

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Geomaterials 2012年第1期2卷 19-23页

作者： Makhaly Ba meissa fall Oustasse Abdoulaye Sall Fatou Samb 不详

This paper presents the results of research conducted to investigate the effect of compaction moisture content on Resil- ient Modulus (Mr) of unbound aggregates. Three different aggregates (GRB, Basalt and Bandia limestone) was collect- ed from different sites within Senegal and then subjected to repeated load triaxial tests. Test results showed that the ef- fect of compaction water content is more significant in the dry side than in the wet side. The compaction water content has less effect on the GRB and the Basalt than on the Bandia limestone. GRB and Basalt are cohesionless materials and allow water to drain even during the compaction procedure. Change in water content increases as the compaction water content increases because of the drainage of the excess water during the compaction and loading procedures. For GRB and Basalt, at Wopt + 1.5%, most of the excess water is drained during the compaction of the sample and continue to be drained during the Resilient Modulus test. For the Bandia limestone, this drainage is less significant due to cohesion, absorption and hydratation.

关键词： Resilient Modulus Summary Resilient Modulus Quartzite Basalt Bandia Limestone