Probability-based assessment of post-liquefaction shear strength: An effective stress approach

Sari, Satuk Buğrahan
Although post-liquefaction shear strengths of soils are very small, their accurate estimations are critical for post-liquefaction stability assessments. Due to the large strain nature of the liquefaction problem and difficulties in preparing re-constituted soil samples representing field conditions, laboratory testing-based assessments are not commonly used. Instead, semi-empirical residual strength assessments based on back analyses of liquefaction-induced failure cases are used for the purpose. Earlier studies suggest estimating the undrained residual shear strength of liquefied soils based on the SPT-based capacity parameter of (N1)60. Within the scope of this thesis, available post-liquefaction failure case histories were compiled and studied. A liquefaction state-like framework is introduced to assess the effective stress-based post-liquefaction shear strength of cohesionless soils in the void ratio-mean effective stress domain. Descriptive parameters of the problem are selected as mean grain size (D50), fines content (FC), coefficient of uniformity (Cu), roundness (R), and sphericity (S) along with stress and density state parameters. A probabilistically defined liquefaction state curve is defined in the ln(e) – ln(p’) domain, addressing the nonlinearity in small to larger stress ranges including the crushing responses in very large stresses. The resulting probability-based liquefaction state curves to assess residual shear strength of liquefied soils are shown to be a superior alternative to existing models, founded on a theoretically sounder critical state-like framework.


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Citation Formats
S. B. Sari, “Probability-based assessment of post-liquefaction shear strength: An effective stress approach,” M.S. - Master of Science, Middle East Technical University, 2022.