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From page 179... ... C-1 APPENDIX C LABORATORY EVALUATION OF INFLUENCE OF GEOSYNTHETICS ON CROSS-ANISOTROPY AND PERMANENT DEFORMATION OF UNBOUND GRANULAR MATERIAL The application of geosynthetics has potential abilities to reduce the thickness of base courses, improve performance, and extend the service life of pavement structures. Read the entire page →
From page 180... ... C-2 where 2J is the second invariant of the deviatoric stress tensor; 1I is the first invariant of the stress tensor; 0ε , ρ , β , m , and n are model coefficients; and c and φ are the cohesive shear strength and friction angle, respectively. In this model, the two terms, 2J and 1I Kα + , are incorporated into the Tseng-Lytton model (1) Read the entire page →
From page 181... ... C-3 Table C-1. Gradation of Crushed Granite Aggregate Sieve Size (mm) Read the entire page →
From page 182... ... C-4 Figure C-2. Geosynthetic Location in UGM Specimen Test Methods Cross-Anisotropy Test The cross-anisotropy tests were conducted on both the geogrid-reinforced and unreinforced aggregate specimens using the universal testing machine (UTM) Read the entire page →
From page 183... ... C-5 Table C-4. RLT Test Protocol for Determining Cross-Anisotropic Properties of Geosynthetic-Reinforced and Unreinforced UGM Stress State Static Stress (kPa) Read the entire page →
From page 184... ... C-6 The change in the first stress invariant, 1IΔ , is calculated to be zero, as shown in Equation C-7: 1 12 2 02 s s s s y x y yI σ σ σ σΔ = Δ + Δ = Δ − × Δ = (C-7) The incremental change of the second deviatoric stress invariant, 2sJΔ , is written as: ( ) Read the entire page →
From page 185... ... C-7 1 1 xy xx e x e x x x xe y e xy xy ye x x y x E E E E E E υ υ σ ε σ υ υ ε σ   − −  Δ   Δ     Δ =     Δ     − − Δ      (C-13) where exεΔ is the change in the radial strain due to exσΔ and eyσΔ ; and eyεΔ is the change in the axial strain due to exσΔ and eyσΔ . Read the entire page →
From page 186... ... C-8 test protocol includes seven stress states (i.e., Stress States 1–7) for model calibration and two stress states (i.e., Stress States 8 and 9) Read the entire page →
From page 187... ... C-9 where x geoE − is the horizontal resilient modulus of the geogrid-reinforced specimen; x controlE − is the horizontal resilient modulus of the unreinforced specimen; y geoE − is the vertical resilient modulus of the geogrid-reinforced specimen; y controlE − is the vertical resilient modulus of the unreinforced specimen; geoAR is the anisotropic ratio of the geosynthetic-reinforced specimen; and controlAR is the anisotropic ratio of the unreinforced specimen. The comparison results are shown in Table C-5. Read the entire page →
From page 188... ... C-10 Table C-6. Influence of Geosynthetic on Cross-Anisotropic Properties (Geosynthetic Location: Mid-Height) Read the entire page →
From page 189... ... C-11 Table C-7. Influence of Geosynthetic on Cross-Anisotropic Properties (Geosynthetic Location: One-Quarter below the Middle) Read the entire page →
From page 190... ... C-12 Table C-8. Influence of Geosynthetic on Cross-Anisotropic Properties (Geosynthetic Location: Bottom) Read the entire page →
From page 191... ... C-13 both geogrid-reinforced and unreinforced UGMs at the two stress states, which indicates that the proposed rutting model is accurate to predict the stress-dependent permanent deformation characteristics of geogrid-reinforced and unreinforced UGMs. Table C-9 lists the determined model coefficients for the geogrid-reinforced and unreinforced UGMs tested in this study. Read the entire page →
From page 192... ... C-14 Figure C-5. Comparison of Lab-Measured and Proposed-Model-Predicted Permanent Deformation Curves for Geogrid-Reinforced UGM Figure C-6. Read the entire page →
From page 193... ... C-15 Table C-9. Determination of Model Coefficients for Geogrid-Reinforced and Unreinforced UGMs Material Type Permanent Deformation Model Coefficients ε0 ρ β m n Unreinforced 0.149 72.4 0.247 1.70 −2.16 TX-1 Middle 0.076 48.3 0.174 1.73 −2.12 TX-2 Middle 0.068 82.1 0.165 1.84 −2.21 BX-3 Middle 0.082 31.2 0.182 1.64 –2.01 TX-2 One-Quarter below Middle 0.093 62.5 0.159 1.62 –2.03 TX-2 Bottom 0.142 35.1 0.294 1.79 –2.26 GT-4 Middle 0.112 60.4 0.261 1.76 –2.18 References 1. Read the entire page →

From page 179...

... C-1 APPENDIX C LABORATORY EVALUATION OF INFLUENCE OF GEOSYNTHETICS ON CROSS-ANISOTROPY AND PERMANENT DEFORMATION OF UNBOUND GRANULAR MATERIAL The application of geosynthetics has potential abilities to reduce the thickness of base courses, improve performance, and extend the service life of pavement structures.