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Effect of Initial Static Shear Stress on Undrained Cyclic Resistance of Well Graded, Medium Dense Gravelly Soils by Cyclic Triaxial Tests

Seyed Ghafouri, Mohammad Hosein | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50545 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Haeri, Mohsen
  7. Abstract:
  8. Softening and liquefaction of granular soils due to earthquakes have been a major cause for much destruction in preceding decades. This phenomenon mostly occurs in sandy soils, yet its occurrence has also been reported in gravelly soils in the last three decades. Despite the numerous researches which have investigated the undrained cyclic behavior of gravelly soils during earthquakes, there are still some aspects that need further study.This research investigates the effect of initial static shear stress on undrained cyclic resistance of a well graded, medium dense gravelly soil by conducting a series of cyclic triaxial tests. The 23 performed tests are categorized into 5 groups with different initial static shear stress ratios of ( ) 1.0, 1.1, 1.2, 1.4 and 1.6. Tests were performed on specimens with a relative density of 45-50% (with mean value of 48%) and a confining pressure of 100 kPa. For each group of tests, the liquefaction behavior of the tested gravelly soil has been studied by implementing different cyclic stress ratios (CSR). Furthermore, the effect of membrane compliance has been eliminated during the tests using a special approach for specimen preparation.The results show that increasing the initial static shear stress under the tested conditions has increased the undrained cyclic resistence of the tested gravelly soil. Moreover, the presence of initial static shear stress not only has affected the amount of pore water pressure ratio at failure, but also has influenced the pore water pressure generation regime
  9. Keywords:
  10. Cyclic Triaxial Test ; Liquefaction Resistance ; Membrane Compliance ; Initial Static Shear Stress ; Gravely Sand ; Reconstituted Samples

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