Evolution of shear wave velocity during triaxial compression
TT Dutta and M Otsubo and R Kuwano and C O'Sullivan, SOILS AND FOUNDATIONS, 60, 1357-1370 (2020).
Accurate design of geotechnical structures requires precise estimation of the shear wave velocity (V-s) and the small-strain shear modulus. However, the interpretation of V-s data measured in deformed/sheared soil has not been extensively considered. This study used a triaxial apparatus equipped with planar piezoelectric transducers to monitor the evolution of V-s during triaxial compression of cohesionless soils. Recognizing that the grain shape and surface characteristics affect the overall mechanical response of granular materials, various natural sands and glass bead samples were considered. Discrete element method (DEM) simulations using spherical particles were carried out to compute particle-scale responses that cannot be measured in the laboratory. The experimental results revealed that the V-s values for samples with different initial densities tend to approach one another and have similar values (merge) at large axial strains. This merging occurs at a lower strain level for spherical particles in comparison with non- spherical particles. The linear V-s-void ratio relationship, which is often developed and used for homogeneous and isotropic stress states, is no longer applicable during shearing. It is the mean coordination number that dictates the evolution of V-s during triaxial compression. Furthermore, the axial strain at which the peak V-s is achieved is found to be comparable to the axial strain at which specimen dilation takes place. (C) 2020 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.
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