Funes C.,Seprobia Soil Testing Laboratory
Bulletin of the International Institute of Seismology and Earthquake Engineering | Year: 2011
Disturbance effects on dynamic properties of saturated sand were evaluated in the laboratory by means of cyclic undrained triaxial tests. For this purpose, undisturbed samples were subjected to deformation and liquefaction tests, the sand that constituted the undisturbed samples was kept and oven dried to reconstitute samples. From the shear modulus ratio-strain dependency curves it is shown that there is no significant effect between undisturbed and reconstituted samples for consolidation stresses of 150 and 300 kPa, anyhow as this parameter was reduced the effect turned evident. Damping ratio was also object of analysis, and very slight effects were noticeable for a consolidation stress of 75 kPa. Bender element tests were performed, and P-wave velocity for each sample remained fairly constant in spite of changes in consolidation stress and disturbance condition, and for S-wave velocity the bender element tests confirmed the results from deformation tests, the difference between both disturbance conditions represented a minor divergence. Liquefaction tests were also carried out, when comparing the shear modulus against the liquefaction potential value a very scattered plot was obtained, reflecting that a large difference in liquefaction potential is present due to the significant change in soil fabric or internal structure, even among undisturbed samples. A relationship representing disturbance effects is presented in terms of a maximum shear modulus ratio and liquefaction potential ratio.