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.