1179
Interpretation of the Effect of Compaction on the Mechanical Behavior of
Embankment Materials Based on the Soil Skeleton Structure Concept
Interprétation de l’effet de compactage sur le comportement mécanique des matériaux de remblai
basée sur le concept de structure des sols
Sakai T., Nakano M.
International Member, Nagoya University,Japan
ABSTRACT: In this research, triaxial compression tests were carried out on 5 materials having different grain size distributions and
compaction properties to determine the mechanical properties of compacted soil. In addition, the triaxial test results were reproduced
using the SYS Cam-clay model to interpret the mechanical behavior of the compacted soil and the effect of compaction on soil based
on the soil skeleton structure concept. Also, seismic response analysis of embankments constructed using these soils was carried out
using GEOASIA to determine the relationship between the compaction properties and the seismic stability of embankments. The
following were the main conclusions. 1) The maximum deviator stress increased with the increase in degree of compaction Dc, but
the trends in the increase differed depending on the material. 2) The mechanical behavior of the compacted soil could be reproduced
using the SYS Cam-clay model using one set of material constants for each material. 3) It was found that when the Dc is increased,
the seismic stability is increased and that as the maximum dry density increased, the seismic stability increased.
RÉSUMÉ: Dans cette étude, nous étudions les caractéristiques mécaniques de sols compactés en mettant en œuvre des essais de
compression triaxiale sur 5 échantillons ayant des caractéristiques de granulométrie et de compactage différentes. En outre, nous
reproduisons les résultats des essais triaxiaux grâce au modèle SYS Cam-clay d'équation constitutive d'élastoplasticité. Nous avons
également effectué l'analyse de la réponse sismique de la déformation des remblais ainsi créés en utilisant le programme d'analyse
dynamique de déformation finie eau-sol GEOASIA pour comprendre la relation entre les caractéristiques du compactage et les
performances sismiques du remblai. Les principales conclusions sont indiquées ci-dessous. 1) Avec l'augmentation du degré de
compactage, la la contrainte axiale maximale est augmentée, mais cette augmentation dépend de la nature de l'échantillon. 2) Il a été
possible de reproduire le comportement mécanique des sols compactés à l'aide du modèle SYS Cam-clay. 3) Quand le degré de
compactage augmente, il a été constaté que plus la densité sèche maximale de l'échantillon est grande plus importante est sa résistance
aux tremblements de terre.
KEYWORDS: compaction, embankment, triaxial compression test.
1 INTRODUCTION
The stability of the embankment is progressing since
fundamental principle of soil compaction proposed by Proctor
(Proctor, 1933), and many researcher and engineer have studied
and improved quality control standard by compaction
．
After
Han-Shin Awaji Earthquake disaster, road earthwork guideline
for construction of embankment was revised to evaluate the
seismic resistance of embankments, and design principles are
changing from being specification based to being performance
based. However, locally occurring materials are still used as
embankment materials, and quality control of embankments is
carried out using the Dc, so doubts remain regarding whether
good quality embankments are being produced. In addition,
because prediction of the deformation behavior of embankments
due to earthquakes is extremely important, a theory for
reproducing the mechanical behavior of compacted materials to
enable prediction of the deformation behavior of embankments
in an earthquake is necessary.
In this study, 5 types of soil material with different grain size
distributions and compaction properties were selected, and the
compacted soil specimens were subjected to CU triaxial tests,
with the objective of obtaining basic data to reproduce the
mechanical behavior of various materials after compaction. The
shear behavior after compaction was compared and examined in
accordance with the differences in the materials. In addition, the
effect of compaction on the mechanical behavior of
embankment materials was interpreted based on the soil
skeleton structure concept by reproducing the mechanical
behavior using the elasto-plastic super/subloading yield surfaces
Cam-clay model (hereafter referred to as the SYS Cam-clay
model) (Asaoka et al. 2002). Also, seismic stability analysis of
embankments were carried out using the soil-water coupled
finite deformation analysis program GEOASIA (Noda et al.
2008), which incorporates the SYS Cam-clay model, to
determine the relationship between the compaction properties
and the seismic stability of embankments.
2 PHYSICAL AND COMPACTION PROPERTIES OF
EMBANKMENT MATERIALS
Five types of materials were examined in this study and are
referred to as materials A, B, C, D, and E (Nakano et al. 2010,
Yokohama et al. 2010). Fig. 1 shows the grain size distributions
of the 5 materials. Fig. 2 shows the results of compaction tests
on the 5 materials. The compaction tests were carried out by the
A-b method for materials B and D, by the A-a method for
materials A and C, and by the A-c method for material E. It can
be seen that as the amount of coarse-grained fraction of the
material increased, the maximum dry density increased and the
optimum water content decreased.
