Journal Published Online: 01 December 2000
Volume 23, Issue 4

Evaluation of Gravel Stiffness by Pulse Wave Transmission Tests



Laboratory techniques for the measurements of very small strain stiffness parameters of coarse-grained materials include: (a) static tests using local strain transducers like LDTs and (b) wave propagation measurements performed using bender elements, shear plates, and so on. The former method has been employed for most kinds of soil, while the use of wave propagation methods has been restricted to small specimens of sand and clay. At the University of Naples Federico II (DIG), a simple device to generate and monitor compressional and shear waves has been designed to be used in large-scale triaxial apparatuses. The testing device was first used on densely compacted gravel specimens in a large triaxial apparatus in Naples and, after some further improvements, also in another large triaxial cell in Tokyo. In the tests carried out in Tokyo, dynamic and static measurements were performed simultaneously on the single gravel specimens. In this paper, the details of the new system are presented and the results are discussed. The comparison between stiffness moduli evaluated by dynamic and static measurements shows that density, stress state, and strain history effects are similar, but that the dynamically measured stiffness values are consistently larger, about two times, than the statistically determined ones. Since the stiffness of gravels has proven to be strain rate independent, possible reasons for this difference are addressed.

Author Information

Modoni, G
University of Cassino, Cassino (Fr), Italy
Flora, A
University of Napoli Federico II, Napoli, Italy
Mancuso, C
University of Napoli Federico II, Napoli, Italy
Viggiani, C
University of Napoli Federico II, Napoli, Italy
Tatsuoka, F
University of Tokyo, Tokyo, Japan
Pages: 16
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Stock #: GTJ11071J
ISSN: 0149-6115
DOI: 10.1520/GTJ11071J