Análise global de estabilidade de taludes e setorização de cava em uma mina de mármore

Abstract

A global slope stability analysis of an open pit mine is an indispensable process for mining. It is necessary in all mining stages, from the design of the pit, production of the mineral resource to the closure period, where the recovery or preparation of the pit occurs, according to the future intended use. The main purpose of the stability analysis is to provide security and economics for the company, avoiding the possibility of slope failures. The main goal of this work is to apply the slope stability analysis in an active marble open pit mine, aiming at the application and integration of geotechnical methods, with specific software, from data obtained in field stages through the aero photogrammetric survey using UAV (unmanned aerial vehicle). From the observations and data obtained, the pit was divided into four sectors: Gray Marble (zone 1), White Marble (zone 2), Pink Marble (zone 3) and Waste (zone 4), defined according to slope orientation, discontinuities and lithological variations. After the sectorization, stereograms are produced for each sector, where the kinematic analysis was performed to visualize whether or not the geometric conditions were met to generate wedge, planar or toppling failures. For the case of the conditions were met, safety factor analysis was performed in each one, aiming to analyze if there is stability of the slopes under those conditions. In total, just in two cases of the pit the geometric conditions were met, but only one of them, the safety factor (SF) was below 1,3, when exposed to extreme rainfall. Simulations were performed for nine different slope orientations, using the inclination angles of 80° and 90°, in order to analyze the variation in safety factor and to understand the orientations most susceptible to failure. As a result of the simulations, it was noted that slopes whose dip direction is south are most likely to minor failure, mainly by toppling, due to the fact that the rock foliation dip to the same orientation and serves as failure base plane. The union of these analysis obtained in each sector, allows to check the global stability of the mine. The contributions of this work apply to use of current tools for stability slope analysis in a mine, as well as its use for road cutting slopes or any other civil constructions involving rock slope. In addition, this work contributes locally to future stability analysis in other marble mines in the region, using the UAV technology, which streamlines the collection process, without interfering with mining operations, in addition, allowing the survey in unsafe areas or with access problems. It is expected that this work will yield results that may suggest specific improvements in the geometry of the slopes of a certain sector of the pit. With this, a factor of safetysuitable for each type of failure mechanism observed, will be defined. In the same way the results can also be used for stability analysis in future expansions of the pit in its different sectors.