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Determination of Soil Stiffness ParametersShort Course on Computational Geotechnics + DynamicsBoulder, ColoradoJanuary 5-8, 2004
Stein StureProfessor of Civil EngineeringUniversity of Colorado at Boulder
ContentsGeneral concepts and stiffness of sandHookes lawE-moduli from triaxial testingE-moduli from oedometer testingExamples on the estimation of E
Stiffness of claysUndrained clay behaviorDrained clay behaviorExamples on the estimation of E
Idealized and real stress-strain behavior of soilsIdealized types of stress-strain behaviors: (a) nonlinear elasticModel, (b) linear elastic model, and (c) elastoplastic model
Idealized and real stress-strain behavior of soilsVarious types of elastoplastic behaviors: (a) strain hardening, (b) perfectly plastic, (c) strain softening, and (d) combination of a to c.
Hookes Law of Isotropic Elasticity
Hookes Law of Isotropic Elasticity
Standard Drained Triaxial Test on Sand
Standard Drained Triaxial Test on Sand
Oedometer Test on Sand
Oedometer Test on Sand
Oedometer Test on Sand
Oedometer Test on SandLoose:Dense:This implies:
Summary on Stiffness Parameters: Sand(Laboratory based experience)Loose:Dense:Loose:Dense:Unloading: About 4 times stiffer. n small
Selection of Moduli for FEM-ComputationLayer 1 (extremely loose sandLayer 1:AverageMohr-Coulomb model:Example 1 (loading):
Selection of Moduli for FEM-ComputationExample 2 (unloading):Layer 1 (dense):Layer 3 (medium):Unloading:for both layersMohr-Coulomb model:Layer 1:Layer 3:
Eoed from Cone Penetration Test in Sandsa = 1 to 3a = 3Cone Resistance:Correlation:Literature NC-Sand:Vermeers Experience:Alternatively:
Undrained Triaxial Test on ClayNormally consolidated clay:Cu = undrained shear strength (or Su)
Idealized and real stress-strain behavior of soils
Idealized and real stress-strain behavior of soils
Plate Loading TestsDuncan & Buchignani (1976)
Plate Loading Tests
Summary on Stiffness Parameters: ClayUndrained ConditionsDo not use empirical relationships only. Get good quality experimental data from lab tests, cone penetration tests and vane tests
Drained Behavior for Clays
Drained Behavior for Clays