Engineering Rock Mechanics

Tests on rock masses 187

Figure 11.11 TerraTek servo-controlled triaxial testing machine at Imperial

College as used for thermo-hydro-mechanical testing of discontinuities.

Sections 11.3 and 11.4 have separately included the items in (a) above,
therefore direct testing of rock masses is now discussed. Always remem-
ber, though, that the measured properties and overall characterization will
vary according to the project requirements.
Testing rock masses is a large subject: we provide here an overview of
deformability, strength and permeability testing: for more advanced
treatment the reader is referred to the book by Dunnicliff (1988).
A logical extension of the use of the site investigation borehole is to install
some form of loading within the borehole, so that a force-displacement
curve is obtained and the associated elastic parameters of the rock estimat-
ed. In soil mechanics, pressure meters and dilatometers are used exten-
sively and attempts are continually being made to develop similar
instrumentation for rocks with higher moduli. Rock masses are usually