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Evaluation Curves SWCC for Tropical Peruvian Soils
Évaluation des courbes de rétention d’eau SWCC pour les sols tropicaux péruviens
Carrillo-Gil A.
Ricardo Palma University, Lima, Peru.
Carrillo-Acevedo A.
AC Ingenieros Consultores, Lima, Peru.
ABSTRACT: The geotechnical analysis of this research shows the results of a program conducted in tropical soils of the Peruvian
Amazon plain for over 20 years. With this information a database has been developed. It has collected samples and tests that establish
the characteristics of these unsaturated soils in all watersheds that shape the Peruvian tropical region, using alternative means of
obtaining the characteristic curves and laboratory tests. The results in this paper show geotechnical occurrences that indicate
substantial similarity and differences of stress and deformation behavior of Peruvian tropical soils. The presence of these unsaturated
soils in this region, where unique features of climate and difficult geological formation are present, makes this information very
valuable for engineering design and construction development due to its models applicability to different stress patterns.
RÉSUMÉ : Cet article présente une base de données mise en place avec les résultats d'un programme d’analyse géotechnique mené
sur les sols tropicaux de la plaine amazonienne du Pérou depuis plus de 20 ans. Des essais de laboratoire ont permis d’obtenir les
SWCC qui établissant les caractéristiques des sols non saturés dans les bassins versants qui forment la région tropicale péruvienne.
Les résultats présentés ici montrent les événements géotechniques qui indiquent une similarité substantielle et les différences de
contrainte et de déformation des sols tropicaux du Pérou. La présence de ces sols non saturés dans cette région, où les caractéristiques
uniques du climat et formation géologique complexes sont présents, rend cette information très précieuse pour la conception
technique et le développement de la construction en raison de son applicabilité des modèles pour différents schémas de contrainte.
KEYWORDS: tropical unsaturated soils, suction, soil-water curves.
1 INTRODUCTION
Based on recognized and user-friendly models, SWCC have
been determined with field tests results and lab soil tropical
sampling gathered in the Peruvian Amazonian region for more
than 20 years (Carrillo-Gil, 1983). With that feedback, it was
possible to elaborate SWCC ranges that represent probable
tropical soil behavior as non-saturated geotechnical material.
The results from the considered samples for this study were
taken from engineering projects and consulting works
developed in the Peruvian Amazon region. This area is difficult
to access because of its environmental conditions and
geomorphology. For those reasons is very important to come
out with Peruvian tropical soils SWCC grouped with distributed
ranges for each of the five hydrographic watersheds. This
information is very valuable for future relevant projects that are
going to be developing in the study region.
2 SITE CONDITIONS IN AMAZON PLAIN
The general geology considers that a large part of the Amazon
region has stayed covered during the interglacial periods of the
quaternary by an interior sea of shallow water when the level of
the oceans had 100 meters above of the existing now (330,000
years ago). It also to fluctuate during several glacial and
interglacial periods forming terraces throughout the water
courses, dropping to 100 meters below of the original level
during the last Glacial Era (17,000 years ago) and remaining in
these deep channels the large rivers, between them the Amazon
river, raising afterwards to the current level (6,000 years ago).
The accomplished studies establish that in the high jungle and
in the limits of the low jungle are found many igneous rocks as
sedimentary, while in the low jungle prevail residual soils
originated by the sedimentary rocks of the tertiary and
quaternary and mainly sandstones, shales and clays form them
(Fig 1).
Figure 1. High and low jungle location in the Peruvian Map.
The general description of the geomorphology of the
Amazon region indicates that the low jungle is substantially flat
and as said remains, its height varies between 80 to 400 meters
above mean sea level. Due to this small difference of elevation,
the rivers flow slowly, getting in the dry station the appearance
of lakes. This region of the Amazon plain can be indicated as
advanced erosion type. The Amazon Plain is characterize by its
