The interpretation of advanced triaxial tests for the assessment of small strain stiffness

Abstract

The measurement of small strain stiffness of soils is affected by the techniques and procedures used in advanced triaxial tests, including the connection between the internal load cell and the sample top platen, the resolution of the instrumentation, the ratio of shearing axial strain rate to preceding creep strain rate. The interpretation of the measured data needs to consider how these factors have affected the measured stress-strain response of a sample. This paper reviews the current practice for performing advanced triaxial tests and discusses the interpretation of data resulting from advanced triaxial tests aimed at measuring the true stiffness of soils. It is concluded that the interpretation of the small strain stiffness of stiff clays affects the shape of the stiffness curve at medium to large strain levels and it is therefore relevant for engineering problems. Suitable specifications as well as a detailed review of the results of the tests are required to ascertain the reliability of the measured stiffness.