The mechanics of blocky material
Abstract
Photoelastic models are constructed to examine the stress
distribution in discontinua. To this end photoelastic
material namely an epoxy resin (Araldite D) is used and
a 22 in. diffusion polariscope constructed.
Initially simple experiments examining slip are
performed and these show that by varying the constraints on
the surrounding blocks, the stress distribution and
deformational response are altered. The effect of rotation
appears to be most important in determining what deformational
response will result.
Mass reaction of a system of blocks are then examined
by measuring both deformations and stress distributions.
The deformational measurements show that the assessment of
effective moduli is most restrictive as to make the use of continuum concepts in the form of analogue methods
suspect.
A numerical method of analysing the photoelastic data
is developed and simple tests show that this has great
potential in furthering the examination of discontinuum
models. In the examination of the blocky mass models
the prevalence of tensile stresses and conditions for the
development of effective tensile strains are readily
observable.
Application of the experimental techniques developed to
a field situation at the Mount Isa Mines shows that the
experimental methods developed could greatly help in
correlating the field situation with the recently
developed numerical methods.