ISSN: 1945-7545
CODEN: GTJODJ
Published Online: 24 January 2013
Page Count: 9

Free–Free Resonance Testing of In Situ Deep Mixed Soils

Guimond-Barrett, Antoine
IFSTTAR, Paris Cedex 15,
Université du Havre, 76058 Le Havre Cedex,

Nauleau, Elodie
IFSTTAR, Paris Cedex 15,

Le Kouby, Alain
IFSTTAR, Paris Cedex 15,

Pantet, Anne
Université du Havre, 76058 Le Havre Cedex,

Reiffsteck, Philippe
IFSTTAR, Paris Cedex 15,

Martineau, François
IFSTTAR, Paris Cedex 15,

(Received 25 April 2012; accepted 23 October 2012)

Abstract

This paper focuses on the use of free–free resonance testing (FFR testing) applied to the characterization of stabilized silt and sand specimens treated in situ by deep soil mixing. The aim of FFR testing is to measure the natural frequencies of free vibration of the tested specimen. Compression and shear wave velocities, seismic moduli and Poisson’s ratio can be determined from these frequencies. Block samples were taken from soil–cement columns installed at a test site near Paris, France. Specimens of 100 by 50 mm (height to diameter ratio of 2) were cored from these blocks and submitted to FFR testing in the laboratory. The measured resonant frequencies were very repeatable for all specimens tested, validating the use of free–free resonance as a rapid testing method for the characterization of fairly heterogeneous stabilized soil specimens. It was found that both P-wave and S-wave velocities increase nonlinearly with unconfined compressive strength. A linear correlation between strength and dynamic stiffness was observed. Free–free resonance test results can be correlated with index parameters such as density and porosity and used for preliminary assessments of static stiffness as all these parameters varied linearly with measured wave velocities.

Keywords:
deep mixing, free-free resonance testing, stabilized soils, cement

Paper ID: GTJ20120058
DOI: 10.1520/GTJ20120058
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