2453
Displacement rigid inclusions
Inclusions rigides refoulées
Cirión A., Paulín J.
Soletanche-Bachy-CIMESA, Mexico
Racinais J.
Menard, France
Glandy M.
Soletanche-Bachy-Pieux, France
ABSTRACT: In soils with poor mechanical properties and in areas where the generation of excavation debris is an issue, given the
restrictions regarding its disposal, the solutions of massive soil improvement with displacement rigid inclusions solve both needs. In
this paper we describe the basis of the constructive procedure of displacement rigid inclusions. We explain the concept of
improvement with this kind of inclusions; we itemize the bases of their design, and describe their construction sequence, highlighting
the controls during the execution to ensure quality.
RÉSUMÉ: Dans les sols ayant des propriétés mécaniques faibles comme dans les zones où l’élimination des matériaux produits des
travaux représente un problème, les Inclusions Rigides avec refoulement de sol donnent des solutions à ces deux situations. L’article
explique le concept des solutions d’amélioration des sols en utilisant la technique des Inclusions Rigides, donne les bases du
dimensionnement, et décrit la séquence de construction des inclusions Rigides en insistant sur les contrôles utilisés pour assurer la
qualité finale.
KEYWORDS: soft soil, rigid inclusion, displacement of soil, excavation debris.
1 INTRODUCTION
When studying what type of foundation is best suited to
withstand the shock that a new building (structure) will impose
on the soil, it is necessary to check not only the limit conditions
for failure, but also the limit conditions of service, including
total and differential settlements.
Being successful in the choice and design of the type of
foundation to be built largely depends on the control of two
variables: load and settlement. Nevertheless, there are additional
parameters that also play an important role in the decision
process, such as the cost of the foundation with respect to the
total cost of the project, construction time and —increasingly—
the impact on the environment.
The foundations based on rigid inclusions (system structure
massive soils improvement) have experienced a boom in recent
years, especially in works on large areas subjected to uniform
vertical loads. While this is not a new concept (wooden
inclusions were used since prehispanic times in Mexico —see
Auvinet, G., 2006—), there is now specialized equipment
capable of building concrete rigid inclusions following special
procedures that not only achieve higher production results, but
also greater depths and better loadbearing capacities. They also
respect strict quality controls. This gives us the possibility to
propose foundations based on the installation of grids of rigid
inclusions made of poor concrete that meet specific technical
requirements regarding load bearing capacities and the
reduction of settlements. They are also attractive: economically
and for their constructive feasibility, as well as for their reduced
construction times and the quality of their execution.
Displacement inclusions in particular have the great
advantage of not generating construction debris, which benefits
the environment and reduces or eliminates the cost of its
removal. In soils with a large frictional component, the ratio of
voids surrounding the inclusion is reduced by the incorporation
of the concrete so that the relative compactness of the material
increases, as well as the perimeter friction of the inclusion-
ground. The construction process of the displacement rigid
inclusion guarantees quality control in the execution, so the
concrete is placed continually and safe from contamination.
2 BASES OF DESIGN
The goal is to install a set of inclusions in soils with low bearing
capacity and/or highly compressibility to create a layer of
compound soil-inclusions material that has better mechanical
properties.
The improvement or reinforcement of soils with rigid
inclusions is commonly used to ensure bearing capacity and/or
reduce settlements in the following types of work:
� Slabs,
� Superficial footings (isolated or continuous),
� Embankments, landfills,
� Work or storage yards.
The solution is characterized by the fact that the traditional
mechanical link between the pile and the structure in deep or
mixed foundations does not exist. A distribution layer, also
called a Load Transfer Platform (LTP), is usually placed
between the inclusions and the structure to be supported, and
this is what marks the difference between piles and inclusions.
The distribution layer spreads the acting loads on the slab or
other covering surface towards the underlying soil-inclusions
setup. The system described is configured as shown in Figure 1.
If there are concentrated vertical loads from one column,
isolated or continuous footings can be used to directly transmit
the loads to the soil-inclusions setup.
