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Impact of Changes in Matric Suction on Dynamic Properties of Unsaturated Silty Soil from Small to Large Strain During Drying Path

Banar, Shaya | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52422 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Haeri, Mohsen; Khosravi, Ali
  7. Abstract:
  8. Shear modulus and damping ratio are of the most important parameters for geotechnical structures during dynamic and seismic loading. Secant shear modulus is the slope of hysteresis shear stress-shear strain loop, and damping ratio is indicative of dissipation of waves energy during propagation in the soil. These parameters mainly depend on void ratio, stress state, and shear strain of the soil. Climate changes cause some drying and wetting process which changes the soil state from saturated to unsaturated form. Previous researches indicated that the shear modulus and damping ratio change with the amount of matric suction. During the drying process, the matric suction increases,therefore, shear modulus increases and damping ratio decreases. Most of the researches on dynamic behavior of unsaturated soils have been performed in small-strain, and there are few studies that have measured the dynamic response of unsaturated soils in medium to large strains. In this study an unsaturated resonant column- torsional shear devices which is developed at Sharif University of Technology has been used. Shear Modulus and Damping Ratio of the tested silty soil were measured for matric suctions of 0 to 200 kPa. In this regard eight unsaturated silty specimens with a relative density of 64 % have been tested.One of the outcome of this study is development of a model for unsaturated silty soils which increases the precision of the study on geotechnical structures during dynamic and seismic loadings
  9. Keywords:
  10. Unsaturated Soil ; Shear Modulus ; Damping Ratio ; Resonant Column-Torsional Shear Apparatus ; Shear Strain

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