New developments on the interpretation of in situ vane test data

Abstract

ln this paper a method is proposed to estimate stress-strain parameters, including the shear modulus, G, from in situ vane test data. Toe field data of more then two hundred (200) tests carried out in the soft, sensitive clay deposits of Azambuja, are analysed. Toe assessment of the results show that the field data have to be corrected to take in to account the stiffness of the vane's spring and that the current procedures of the te:.1 need to be changed in order to estimate meaningful stress-strain parameters. Toe stress-strain parameters obtained from the vane tests are first compared with the correspondent parameters obtained from triaxial and simple shear tests that were carried out on undisturbed samples retrieved from the same soft clay deposits. Secondly these parameters are used with a two-dimensional (2D) and three dimensional (3D) finite element analysis to simulate the vane test itself and with 2D finite element analysis to simulate the foundation failure that occurred in the soft clay deposit at Azambuja during an embankment construction.