MACÊDO, A. J. B.; http://lattes.cnpq.br/9796505055029387; MACÊDO, Alexandre José Buril de.
Abstract:
The liberalization of international trade which was implemented by the Brazilian
government in 1990 made possible to import sophisticated equipment for the
ornamental stones industry. That fact had a positive influence helping the country
to become an important player in the international market of the ornamental stone
economic sector.
The Northeast region, mainly in its dry portion, has a large exposure of crystalline
pre Cambrian rock, which has great potential for production of dimension stone
granitic rocks. At present, important progress has been achieved in the
ornamental rock industrial sector, and there are more than a hundred different
types of rocks of commercial value for exporting already cataloged. In spite of
that, the overall performance of Brazil in the international market has decreased
to seventh in rank, having the country been surpassed by Portugal and South
Africa.
This research has the objective of suggesting technical procedures for the
empirical analysis of rock masses suited for the extraction of covering stones.
Generic aspects are treated in the search of more rational quarrying methods,
with emphasis in the following characteristics: regional geology and
geomorphology; mineral and petrographic aspects; and geotechnical
characterization of the rock mass.
The methodology adopted consisted in bibliographic survey and field
observations. It has been possible to define the present situation of the sector of
row blocks from the commercial and economic points of view; principles and
techniques for estimating in situ stresses; evaluation of methods for rock mass
classification oriented to ornamental rock; observation of geologic aspects and
state of stresses at eight quarries.
In order to prepare quarrying plans it has been concluded that the following
sources of information should be used during the early stages of prospecting:
analysis of previous works about the structural geology of the region; petrographic
study in oriented rocks; analysis of topographic characteristics of the area; and
analysis of rock cores.
It has also been observed that rock mass classification systems oriented to
dimension stones should use RQD index with caution, since it is generally equal
to 100 in that case, and that Hoek-Brown failure criteria is useful in establishing
the maximum limit of stress that the rock mass can withstand. The usefulness of
Laubsher classification system in estimating the mean size of blocks is
highlighted.
The final conclusions include recommendations of practical procedures, which
may be adopted for geologic exploration of dimension stone granitic rocks,
according to their different genetic types.
