Analysis of a reinforcement detail in a bar reinforced soil-mix wall

Abstract

Soil-mix walls are subsoil walls, which are constructed by in situ mixing of soil
with cement and water. The technique was initially used as a ground improvement
technique and is now being developed as construction method for walls
with a structural purpose. Currently these walls are reinforced with large steel
profiles, which requires a large quantity of steel. Replacing the profiles with
bar reinforcement might lead to a decrease in required material quantity and
thus a reduction of material costs.
There are multiple aspects which influence the possibilities and limitations
of bar reinforced soil-mix walls. These include predictability of the material
quality, durability and cooperation between soil-mix and the reinforcement.
The aim of this project was to contribute to this research by analysing one
of the influential aspects. The specific goal of this research project was to
analyse the capacity of a reinforcement detail within a soil-mix wall and define
the governing failure mechanism. The research combined an experimental and
numerical approach to the subject.
The critical detail was chosen based on the Huybrechts et al. (2016), Ganne
et al. (2010), Dörendahl et al. (2004) and contact with soil-mix experts. To
model this detail in a finite element model, in 2D and 3D, material parameters
were derived from Denies et al. (2012a), Denies et al. (2014), Denies et al.
(2015a) and performed physical tests. The 2D models represented the most
critical sections of the detail based on the theoretical stress distribution. The
geometrical parameters of the reinforcement design were varified in the models
to provide insight in the influence of the design on the capacity.
The model results were used to define an preliminary set of design guidelines
for the reinforcement cage, related to the depth of the wall. Since only
the capacity of the detail is considered, these guidelines are not suficient for
a complete design of a bar reinforced soil-mix wall and can only serve as an
initial indication.
In conclusion, the reinforcement detail is most sensitive to failure due to vertical
splitting and has suficient capacity for acceptable wall depths. As stated
before there are multiple aspects relevant to the feasibility of bar reinforced
soil-mix walls. The predictability of the material quality, the bond with the
reinforcement and the durability of the soil-mix strongly influence the final
capacity and behaviour of the wall. Therefore it is important to perform further
research on these, and other, aspects to conclude on the total structural
integrity of an entire bar reinforced soil-mix wall.