Modelagem geológico-geotécnica em projeto greenfield de mina a céu aberto em Santana da Boa Vista - RS

Abstract

A greenfield project consists of an enterprise that is being installed in a location where there is currently no pre-existing infrastructure. In this context, there is the research project required by a mining company in the northern region of the municipality of Santana da Boa Vista/RS. The project suggests the implementation of a mining enterprise to extract marble, which is popularly known in the region as limestone, an essential product for the economy of the center-south region of the state. The main objective of this work is the geological-geotechnical modeling of this case study. A secondary objective is to define suitable ranges for slope angles based on the Q-Slope classification system. The data referring to the rock mass used in the construction of the models were obtained by collecting the integration of existing data, geotechnical description of drilling holes, interpretation of the rock mass discontinuities and its characteristics, in addition to the geomechanical classification by Rock Mass Rating systems (RMR) and Q-Slope. Subsequently, the collected data were georeferenced and represented in a three-dimensional way, in order to understand the particularities of the acquired information. In order to obtain a geological model, an implicit modeling was performed based on the drillhole data. From the geological model, a block model was created, and these blocks were interpolated by the inverse distance weighting method, to obtain the geotechnical parameters, RMR, Q-Slope and angle β along the entire region of the model. From the modeling, it is possible to globally visualize the study area, in order to contribute to the definition of the positioning and planning of the future pit. The RMR classification defined the rock mass as Class I and II (very good and good) within the limits of the proposed pit. Finally, the Q-Slope method indicated stable slopes when using face angle values ranging from 64° to 68°. These values obtained are quite conservative, given the knowledge of other mines operating in rock masses of similar conditions with larger angles. However, it is important to note that the value obtained for RQD, one of the parameters used in the calculation of RMR and Q-Slope, may have been influenced by the quality of the drilling.