Volume 8, Issue 3 (September 1985)
Resonant-Column Apparatus for Coarse-Grained Materials
To investigate the low-strain dynamic properties of soils with grain size up to 25 mm (1 in.), a resonant column apparatus for specimens of 150 mm (6 in.) diameter and 450 mm (18 in.) height has been developed. Fine-grained materials can be tested using smaller specimens of at least 50 mm (2 in.) diameter. Compressive and torsional wave propagation at strains of the order of 10−4% and into the nonlinear range (up to approximately 5 × 10−2%) can be investigated at ambient air pressure up to 600 kPa (87 psi). Keeping the amplitude of excitation constant by means of an electronic feedback system, the specimen's resonant frequency and amplification can be found directly from the response curve by recording the amplitude ratio of accelerations at both ends of the specimen as a function of frequency. The equipment can be adapted to special research requirements or used to carry out routine measurements for scientific consulting.