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Assessing the Effectiveness of Rolling Dynamic Compaction
Évaluation de l'efficacité du compactage dynamique roulant
Kuo Y.L., Jaksa M.B., Scott B.T., Bradley A.C., Power C.N., Crisp A.C., Jiang J.H.
The University of Adelaide, Adelaide, Australia
ABSTRACT: Rolling Dynamic Compaction (RDC) is a soil improvement technique, which involves a heavy (6– to 12–tonne)
non-circular module (impact roller) that rotates about a corner as it is towed, causing the module to fall to the ground and compact it
dynamically. This paper focuses on the 4-sided module and aims to quantify the effectiveness of RDC by means of a combination of
field studies and numerical modeling. The field studies involved embedding earth pressure cells beneath the ground at varying depths
and measuring the in situ stress over a range of module passes. In addition, a variety of in situ tests were performed including
penetrometer, field density and geophysical testing to measure density improvement, again as a function of the number of module
passes. The field measurements indicated that the depth of improvement exceeded 2 meters below the ground surface. Numerical
modeling was undertaken using the dynamic finite element analysis software, LS-DYNA; the results align well with those obtained
from the field studies. Parametric studies were also undertaken to determine the influence of varying soil parameters on the
effectiveness of RDC.
RÉSUMÉ: Le Compactage Dynamique Roulant (CDR) est une technique d'amélioration du sol, qui implique un lourd module de
forme non circulaire (6 à 12tonnes), rouleau à impact, qui tourne autour d'un coin lorsqu’il est tiré, ce qui provoque la chute du
module sur le sol et le compacte dynamique. Cet article se concentre sur le module à 4 faces et vise à quantifier l'efficacité du CDR
par le biais d'une combinaison d'études sur le terrain et de modélisation numérique. Les études de terrain ont comporté l’installation
de cellules de contraintes dans le sol à différentes profondeurs et à mesurer ainsi la contrainte lors des passages du module. En outre,
de nombreux essais in situ ont été réalisés, comprenant des pénétromètres, des essais de densité en place et des tests géophysiques afin
de mesurer l’amélioration de la densité en fonction du nombre de passes de modules. Les mesures sur le terrain ont indiqué que la
profondeur de l'amélioration a dépassé les 2 mètres sous la surface du sol. La modélisation numérique a été réalisée en utilisant le
logiciel d’analyse par éléments finis en dynamique, LS-DYNA ; les résultats concordent bien avec ceux obtenus dans les études sur le
terrain. Des études paramétriques ont également été entreprises pour déterminer l'influence de divers paramètres du sol sur l'efficacité
du CDR.
KEYWORDS: Rolling dynamic compaction, impact roller, LS-DYNA
1 INTRODUCTION
Rolling dynamic compaction (RDC) is a generic term used to
describe the densification of the ground using a heavy
non-circular module (of three, four or five sides), that rotates
about a corner as it is towed, causing the module to fall to the
ground and compact it dynamically. An example of RDC is
illustrated in Figure 1. RDC is able to compact the ground more
efficiently because of its greater operating speed – 12 km/h
compared with 4 km/h of conventional rollers. Due to the
combination of kinetic and potential energies, RDC has
demonstrated improvement to more than one meter below the
ground surface (and greater than three meters in some soils); far
deeper than conventional static or vibratory rolling, which is
generally limited to depths of less than 0.5 m. As a result, RDC
has been used on applications such as land reclamation projects,
compaction of sites with non-engineered fill, in the agricultural
sector to reduce water loss, and in the mining sector to improve
haul roads and construct tailings dams.
Quantifying the effectiveness of RDC via field based trials
has been the focus of different researchers over the years,
including Avalle and Carter (2005), Avalle (2007), Avalle et al.
(2009) and Jaksa et al. (2012). Mentha et al. (2011) conducted
a trial that involved three main focus areas: (a) the use of earth
pressure cells (EPCs) for direct measurements of stress change
to determine the extent of depth of influence and the stress
distribution induced by the RDC; (b) undertaking field tests,
including dynamic cone penetration tests (DCPs) and field
density measurements and the spectral analysis of surface waves
(SASW) geophysical technique to measure and infer changes in
density as a function of the number of module passes; and
(c) conducting a series of laboratory tests (e.g. particle size
distribution, hydrometer test, Atterberg’s limits, standard and
modified Proctor tests) on the samples collected from the site to
characterize the soil. Field-based research typically involves a
team of professional operators and technicians spending days
diligently preparing a test pad, placing and burying EPCs at the
required depth(s) and spacing, undertaking field tests before and
after a number of rolling passes, collecting data from EPCs, and
collecting soil samples for further laboratory testing.
Figure 1. An example of RDC – Broons BH-1300 4-sided impact roller.
Results from field-based research are typically site specific;
supporting the notion that the effectiveness of RDC is highly
dependent on the soil type and site conditions. The influence
depth is typically a measure of the depth to which the imposed
load from the module quantitatively affects the soil; this can
