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Prof. M. Bolton (UK)
"Using centrifuge models to define deformation mechanisms and generate design methods"
The analysis
of comparative digital photographs by Particle Image Velocimetry
(PIV) offers a powerful technique for the demonstration of deformation
mechanisms in soil models. Where small-scale models can be tested in a
geotechnical centrifuge at a sufficiently uniform acceleration to broadly
recreate full-scale stresses, it will follow that soil stiffness and strength
will equally be appropriate to the full scale. If sufficient attention has been
paid to the creation of appropriate boundary conditions, and to the actuation
of a representative construction and loading sequence, the observed mechanism
can be used to deduce the characteristic features of similar processes in the
field. This requires a further step of simplification and mathematical
characterization. Any recommendation for the use of such a mechanism in design
should depend on a consistency check of the conservation of energy in the
model, leading to sufficiently accurate predictions at model scale. Such a
demonstration is consistent with the Mobilizable Strength Design (MSD) method which
has been shown to serve as an efficient means of predicting and controlling
ground deformations. Examples will be given of the behavior of tunnels, deep
excavations and slopes.The analysis
of comparative digital photographs by Particle Image Velocimetry
(PIV) offers a powerful technique for the demonstration of deformation
mechanisms in soil models. Where small-scale models can be tested in a
geotechnical centrifuge at a sufficiently uniform acceleration to broadly
recreate full-scale stresses, it will follow that soil stiffness and strength
will equally be appropriate to the full scale. If sufficient attention has been
paid to the creation of appropriate boundary conditions, and to the actuation
of a representative construction and loading sequence, the observed mechanism
can be used to deduce the characteristic features of similar processes in the
field. This requires a further step of simplification and mathematical
characterization. Any recommendation for the use of such a mechanism in design
should depend on a consistency check of the conservation of energy in the
model, leading to sufficiently accurate predictions at model scale. Such a
demonstration is consistent with the Mobilizable Strength Design (MSD) method which
has been shown to serve as an efficient means of predicting and controlling
ground deformations. Examples will be given of the behavior of tunnels, deep
excavations and slopes.
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