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The measurement of suction stress characteristic curve for a highly collapsible loessial soil

Haeri, S. M ; Sharif University of Technology | 2015

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  1. Type of Document: Article
  2. DOI: 10.1061/9780784479087.230
  3. Publisher: American Society of Civil Engineers (ASCE) , 2015
  4. Abstract:
  5. This paper describes results of an advanced suction controlled triaxial test device on a loessial soil in an attempt to define the constitutive relationship between suction stress and matric suction (suction stress characteristic curve) for highly collapsible soils. Due to the presence of void spaces with different degrees of collapse potential within the soil matrix, the collapse phenomenon in loess is believed to be a continuous-stepwise reduction in volume rather than a sudden drop during wetting. Due to this unique volume change behavior, the definition of the suction stress characteristic curve for loess may require a soil-specific experimental testing approach capable of making precise and continuous measurements of volume change and water outflow during loading. The testing approach includes a pressure-feedback control loop to provide the required pressure equilibrium in the system in the case of any change in pressure due to pore structure collapse and two independent digitized volume change measurement devices to measure possible changes in soil/water volume during testing. Based on the experimental measurements, depending on the applied unsaturated stress state variables (e.g., net stress and matric suction), and the consequent magnitude of wetting-induced collapse, the soil specimen may show different behavior during shear. For higher matric suctions, soil specimens experience small changes in volume during the suction equilibrium stage and shear strength curves show a dilative and brittle behavior as shearing proceeds. At lower levels of matric suction or higher magnitudes of net stress, a ductile behavior in the shear stress curves is observed and most specimens experience a decrease in volume during shear. Experimental results indicate a unique critical state line for specimens sheared under varying stress state conditions when defining the SSCC using the measured shear strength data in this study
  6. Keywords:
  7. Critical current density (superconductivity) ; Sediments ; Shear strength ; Shear stress ; Soil testing ; Soils ; Stress analysis ; Wetting ; Collapse potential ; Constitutive relationships ; Continuous measurements ; Critical state lines ; Experimental testing ; Pressure equilibriums ; Stress state variables ; Volume change measurement ; Soil surveys
  8. Source: Geotechnical Special Publication, 17 March 2015 through 21 March 2015 ; Volume GSP 256 , 2015 , Pages 2482-2491 ; 08950563 (ISSN) ; 9780784479087 (ISBN)
  9. URL: http://ascelibrary.org/doi/abs/10.1061/9780784479087.230