The study investigates the possibility to incorporate fracture intensity
and block geometry as spatially continuous parameters in GIS-based
systems. For this purpose, a deterministic method has been implemented
to estimate block size (Bloc3D) and joint frequency (COLTOP). In
addition to measuring the block size, the Bloc3D Method provides
a 3D representation of the shape of individual blocks. These two
methods were applied using field measurements (joint set orientation
and spacing) performed over a large field area, in the Swiss Alps.
This area is characterized by a complex geology, a number of different
rock masses and varying degrees of metamorphism. The spatial variability
of the parameters was evaluated with regard to lithology and major
faults. A model incorporating these measurements and observations
into a GIS system to assess the risk associated with rock falls is
proposed. The analysis concludes with a discussion on the feasibility
of such an application in regularly and irregularly jointed rock
masses, with persistent and impersistent discontinuities.