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th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
stress concentration increases. However, upon full separation of
the mesh, this tip stress is relieved as propagation is halted. The
mesh is then free to shrink further subject to the basal friction
condition.
8 REFERENCES
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Figure 7 Distribution of total stress in the horizontal orientation.
The formation of shallow compressive stress concentrations
at the upper surface, such as that shown between existing cracks
in Figure 7 is considered to be the indicator of crack initiation
loci. The progressive development of such surface stress
concentrations away from previous crack formation is evidence
of sequential crack formation. The incorporation of tensile
strength variability across the many interfaces has allowed this
phenomenon not to dominate, therefore avoiding symmetry in
the resultant crack pattern. Simultaneous growth of primary
cracking at spacing relative to the progressive development of
surface stress is evident in Figure 6a, shown by the fully
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has led to stress relaxation and inhibited further pervasive
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Growth of basal tensile stress concentrations are shown to
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6 CONCLUSIONS
This work is set in the context of cracking due to seasonal
drying in compacted, engineered fills used in the construction of
infrastructure embankments.
The model presented is capable of replicating the non-linear,
partially saturated state that results from the application of a
drying flux. Through incorporating interface elements, the
model is not only able to model the stress field generated
through drying but is capable of simulating the cracking
behaviour of an engineered fill undergoing desiccation. It is
recognised that the placement of predefined, potential cracking
sites has the inherent tendency to bias the distribution of
cracking. However, attempts have been made to include a
degree of heterogeneity in tensile strength throughout a finely
discretised mesh. Through this, a combination of spontaneous
and sequential crack initiation processes is captured much like
the development of primary and second order cracking recorded
in the field.
The use of a dynamic, evaporative boundary condition is
incorporated in an attempt to capture the transient nature of
surface permeability under drying.
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7 ACKNOWLEDGEMENTS
The authors would like to thank Stuart Patterson for help
with laboratory work, Dr Joao Mendes for triaxial data and Dr
Peter Helm for his helpful advice in the use of the numerical
software.
van Genuchten M. T. 1980 A closed-form equation for predicting the
hydraulic conductivity of unsaturated soils.
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892-898
