Hazard Assessment of Bedrock Discontinuities Using Integration of Structural Data and Geotechnical Characterization

foundation bedrocks and the stability of many slopes. Moreover,
assessing and analyzing the different slope failures through
fieldwork and laboratory tests of the intact rock mass is important to
determine discontinuities' geometrical and geo-engineering
parameters. The Northern Galala Plateau is considered a typical
case study of instability problems due to excessive bedrock
discontinuities. The present study deals with the mapping and
assessment of bedrock (Paleozoic sandstones) discontinuities using
structural mapping/analysis and geotechnical qualifications as an
integrative approach. The study was started by collecting structural
data, joint surveying and delineating fault zones as well as highly
fractured zones. In addition, the geotechnical qualifications and
stability of slopes were assessed using kinematic analysis and Rock
Mass Rating (RMR) of discontinuity sets at the lower slope.
Quantitative descriptions and statistical distribution of fractures at
the study site were well defined. The kinematic analysis of
sandstone bedrock masses revealed wedge and/or toppling failures
which are controlled by uncomplimentary discontinuities. As a
result, RMR values suggested the majority of foundation bedrock is
classified as good rock II category, whereas RMR for the fault zone
is classified as fair rock III category. Furthermore, discontinuities
could not necessarily lead to instability problems during and after
construction. The present study highlights the influence of
integration between both structural and geotechnical techniques for
suitability assessment in development processes which in turn could
provide important keys for decision-makers.