A Study on the Development of Anisotropic Shear Modulus for Soft Clay during the K_O Consolidation

The anisotropy on shear moduli for K₀ consolidated clay is studied by performing small-strain triaxial tests and bender element (BE) tests on reconstituted Taipei silty clay specimens at different consolidation stresses. The newly developed triaxial testing system was equipped with a high-precision servo motor, a digital pressure controller system, and local measurement sensors. All the specimens were consolidated under the K₀ condition and then subjected to undrained shearing. The bender element tests were conducted along with the process of the K₀ consolidation, and the variation of shear moduli in different orientations with the changing in consolidation stress was observed. The shear wave velocities in two different directions were measured in undrained shearing stage by bender element tests as well. The test results showed that: 1) the shear modulus obtained from the shear wave propagating and vibrating parallel to the bedding plane, i.e. G_hh, is higher than G_vh for clay at K₀ state, 2) the empirical expressions for calculating the anisotropic shear moduli based on function of void ratio, OCR, and stress states were established, 3) the anisotropy for shear moduli measured from bender element tests was observed in the shearing process as well as in the consolidation stage.