Mechanical Models of Fractured Rock

Rock mass, as a rule, is a geological mass cut by the geological structural weak planes. It's characteristic featuers are discontinuity, inhomogenity and anisotropy.The results obtained from the compression tests in a conventional loading machine oa intact rock specimen appear to be inadequate to represent the engineering properties of rock mass,but in utilizing of stiffness testing machine the negative slope part of the stress-strain curves and the fatigue testing curves for the intact rock specimen are more fully representive of the intrinsic rock properties in the mechanical behavior and failure processes.Based on the results of various rock we present two basic mathematical models with variable mechanical parameters,i, e. Hookean body with variable elastic modulus and Saitit-Venant's body with variable yield-limit. From these simple models four mechanical models modelling the properties of the fractured rock have been developed and the corespondending constitutive equations have been developed. From the results of tests for determining the complete stress-strain curve, the parameters in the constitutive equations of fractured rock can de obtained, thus the constitutive equations are given. Based on the comparision between model analysis and testing results it is shown that these models are practicable and applicable,and they provide reference models for the further discussion of the stability of the fractured rock mass and the mechanism of its support.