Caracterização geomecânica de maciço rochoso em uma mineração artesanal paralisada no município de Tauá-CE

Abstract

The interest in artisanal mining of amethysts, which is at a standstill, located in the Quinamuiú mountain range in the city of Tauá, arose from the need to analyze the stability of the excava- tions in order to attest to the safety of the excavations, which are constantly being visited by visitors. on the saw. The general objective of the work was to develop a study of the geome- chanical conditions of the rock mass, as well as the analysis of the local geology and the study of discontinuities. As a work methodology, the digital terrain model was carried out, specifi- cally the topographical recognition of the study area; also, the local geological reconnaissance and stability studies of the underground galleries where, in each analyzed section, measure- ments were carried out in the field of the outcrops, walls and ceilings of the gallery to complement the characterization of discontinuities, this was carried out, analyzing parameters such as orientation, frequency, spacing, persistence, roughness, compressive strength, opening and filling of fractures, culminating in the classification with traditional geomechanical classi- fication systems, represented by RQD - Rock Quality Designation, RMR - Rock Mass Rating, Q - Tunneling Quality Index , and GSI (“Geological Strength Index”). With all the data in hand, the patterns of discontinuities acting in the rock mass were pushed with the software Stereonet and Stereonet / visible geology app. According to the local geology of the ancient small-scale artisanal mining, the geological characterization scores identify migmatized gneisses, diatex- ites, granodiorites and paragneisses as enclosing rocks, belonging to the Tamboril-Santa Quitéria Complex and as a lithology of the Quinamuiú mountain range, acid rocks with high content of silica formed by fine-grained rhyolites. With the analysis of families of discontinui- ties, it can be seen that the greatest influence of the joints as conditions of instabilities in the external part of the gallery have an average attitude of 098o/50 and 041o/56, with a predomi- nance of the WNW-ESE direction. The results indicated a range of classification between reasonable and poor between windows, therefore, entry into the gallery is not considered safe for visitors, according to the results obtained in the study.