Search

Resonant column devices are popularly used to evaluate the shear moduli and damping characteristics of soils at small strain amplitude. To use the resonant column technique it is necessary to accurately know the value of the rotational inertia of the top mass of the apparatus JAto evaluate shear modulus values derived from resonant frequency values. The paper describes a new and simple method for evaluating JAfor a resonant column device using two calibration rods of known geometry. The advantage of this calibration method is that a value of JAmay be determined without having to know the material properties of the calibration specimen. The paper describes the theory of the calibration technique and gives dimensions of typical calibration samples that can be used for resonant column studies. Typical measured calibration values are presented to show the accuracy of the calibration technique.

Automated data acquisition systems combined with appropriate test transducers and dynamic recording equipment can provide the benefits of improved measurement of test values and better use of laboratory personnel in geotechnical testing laboratories. This paper suggests requirements for such data acquisition systems and discusses characteristics that should be designed into the systems to avoid operational difficulties. Tables are provided showing suggested transducer performance characteristics and data acquisition response characteristics.