Engineering Rock Mechanics

172 Anisofropy and inhomogeneify

,/Ipn

Figure 10.6 Schematic of a hybrid computational scheme for excavation and

support design in jointed rock media (from Lorig and Brady, 1984).

Developments aimed at overcoming these difficulties are the use of

hybrid numerical formulations which recognize the advantages of the

continuum and discontinuum component methods. An example is shown

in Fig. 10.6, from the work of Lorig and Brady (1984). Here, a boundary

element solution has been utilized for analysing the far-field, and a distinct

element model used for the near-field. There are advantages in assuming

the material to be a continuum in the far-field while simultaneously

modelling the discontinuities explicitly in the region of interest around the

excavation. Via such a hybrid technique, we are able to model the

discontinuities, tailoring the modelling to the engineering and design

objectives.

We leave further discussion of inhomogeneity and anisotropy until later

chapters and concentrate now on the implications of all the subjects

covered so far on rock mechanics testing techniques.