Pit Slope Configuration for Open Pit Mining – A Case Study (original) (raw)
Related papers
Stability assessment and slope design at Sandsloot open pit, South Africa
Sandsloot open pit is located on the northern limb of the Bushveld Igneous Complex. It is the largest open pit platinum mine in the world. Three major joint sets have been recognized at Sandsloot, which are related to the regional tectonic history. They have an important influence on slope stability in the open pit, notably in terms of planar and wedge failures. Detailed geological and geotechnical data are often a notable unknown factor in the design and operation of an open pit, the lack of which may pose a significant risk to the mining venture. As data are accumulated and used effectively, so the risk of unforeseen conditions is reduced, and accordingly safety and productivity is increased. Usually, the geotechnical work undertaken at an open pit mine is in connection with improving slope stability. At Sandsloot open pit geological and geotechnical data have been obtained by face mapping, scanline surveys, from exploration drillholes and from laboratory tests. Such data have been used to delineate different geotechnical zones in which different types of slope failure have occurred. These are the usual types of slope failure associated with rock masses, namely, planar, wedge, toppling and circular failures. Analysis of the data has allowed optimum design parameters to be developed for these zones which has led to improved slope stability. In other words, this has allowed slope management programmes to be initiated, as well as slope optimization of the hangingwall. The latter resulted in an improved slope configuration and an increase in the ultimate angle of the wall by 71. This has resulted in substantial savings, as well as an improvement in safety. r
Map of the potential geotechnical susceptibility for operational pit slopes
REM - International Engineering Journal, 2019
This article proposes a procedure to elaborate a map that presents the potential risk of failure occurrence in the operational slopes of open pit mines. First, it is necessary to collect the available geological-geotechnical data and perform a field mapping, in order to verify and validate the most representative parameters and to characterize the discontinuity families of the rock mass. Then, the mine should be sectorized, considering all the data collected, the geometry of the operational slopes and its development until the final pit. The next step will be to define and to evaluate which failure modes have greater or lesser potential to occur in the pit and to assign weights to them. In this study, the weathering, planar failure, and plane circular failure potentials were evaluated. As a result, it is possible to develop a map with the susceptibility level of the sectors. This map will help make technical and managerial decisions in order to reduce the risk level of the sectors and to promote an increase in the operational safety of the mine.
Risk Assessment of Open Pit Slope Design at PT Adaro Indonesia
2014
Risk assessment of open pit slope stability is an important aspect to be considered in a decision making of slope design. The risk of slope failure that occurred on the slopes of the mine affect two factors namely the failure probability (FP), and consequences (C) of slope failure. FP is obtained from the collection of the value of Safety Factor (SF) < 1 compared to the total value of SF, while the consequences is estimated from the sectional area multiplied by the width of slope failure. Physical and mechanical properties of sandstone was collected from PT Adaro Indonesia, and tested by “Kolmogorov-Smirnov (K-S)” fitting method to obtain an assumed theoretical distribution that be sued with the character of the original distribution data. “Monte Carlo (MC)” and “Latin Hy- percube (LH)” sampling method is used as a tool to generate sample data, and both methods were compared. Finally Validation is conducted in order to propose an acceptable criteria of FP for single slope of sand...
Slope Stability Of The Middle Stack Of An Open Pit
International Journal of Scientific & Technology Research, 2019
Chimiwungo main open pit has experienced slope failure in the weathered rock formation in the middle stack for a decade now. In this article, the geotechnical analysis was conducted to determine the factor of safety and probability of failure of the middle stack using limit equilibrium method under both drained and undrained conditions. The factor of safety and probability of failure index were calculated as they provide the objective measure of the risk of the failure associated with a slope design. The actual stack performance was compared to various slope stability acceptance criteria with results subjected to a more thorough analysis of the consequences of failure. The study indicates that under dry to semidrained conditions, the factor of safety and the probability of failure were compliant to all the acceptability slope stability failure criterion. This entails under dry and partially drained conditions, the middle stack of the Chimiwungo Open Pit is predicted to remain stable...
Stability Analysis and Failure Mechanisms of Open Pit Rock Slope
Journal of the Civil Engineering Forum
Rock mass in nature tend to be unideal, for it is heterogeneous, anisotropic and has discontinuity. The discontinuity makes anisotropic strength and stress in the rock mass, and also controls the changing of the elastic properties of rock mass. This condition results to disruptions in the rock mass strength balance, and finally drives the slopes to collapse. This study aims to determine the slope failure mechanisms in the area of case study, as well as its variations based on the Rock Mass Rating (RMR), Geological Strength Index (GSI), Slope Mass Rating (SMR), kinematic analysis, numerical analysis and monitoring approach slope movement in a coal mine slope applications. The site investigations were implemented to obtain information about slope collapse. Prior to the collapse, the slope inclination was 38° with of 94 meters height, strike slope of N 245 E and direction of slope surface of 335°. After the collapse, the slope was became 25º; and after the collapse materials were clear...
Slope Stability in a Mining Environment M'haoudatt-Zouerate Site, Mauritania
American Journal of Energy Engineering, 2021
The instability of the M'HAOUDATT pit is a major problem often encountered on the wall composed of a network of fractures located in unfavorable conditions for a very soft geological formation. Therefore, the trend in large openpit mines is to use high-energy blasting to increase conveying performance and crusher throughput. The increase in blasting energy concentration can threaten the integrity of the pit wall. In this paper, we aim to find a suitable plan to stabilize the pit deposit, through analyses of structural and lithological data on the pit walls, with an interpretation of the lateral and depth extensions according to the geological complexity of the deposit. Followed by an analytical treatment of the current pit parameters. Data processing included core classification, kinematic assessment of failure mechanisms based on visual observations on the exposed faces of the expected pit. The results of the laboratory tests were also used to define the rock mass parameters used to establish a stable slope design. The analyses showed the need for an effective strategy to ensure that the slopes won't be damaged by blasting. This wall control strategy aims to produce a fragmented bulk ore pile and a slope as designed and in good condition. A good understanding of the failure mechanisms is necessary to ensure better monitoring of the rock slopes of the M'HAOUDATT pit.
Geological control on slope failure mechanisms in the open pit at the Venetia Mine
South African Journal of Geology, 2003
The Limpopo Belt is a complex accretionary terrane that has undergone numerous deformational events. Tectonically juxtaposed lithology, open to isoclinal folding, cross-cutting and re-activated shear zones, and closely interlayered metamorphic gneisses and schists make pit slope design and maintenance risky. Pit slope design effects the stripping ratio and the "bottom-line" profitability of a mine. The geological model is the basis on which a pit design starts. At Venetia Mine the model is a tight, northward verging syncline that plunges shallowly towards the east-northeast. The geology has been modeled three-dimensionally using GEMCOM software. The jointing patterns have been studied and hypothetically related to the geology. The synform fold model implies three major pit slope design sectors, the (a) southern limb, (b) fold hinge zone and (c) northern limb of the fold. The southern limb experiences predominantly planar failure, a problem that has resulted in a reduction in the pit slope angle from 51 o to 37 o and 44 o in two of the southern domains respectively. The northern limb undergoes bench-scale toppling and wedge failure. The hinge zone suffers only from local wedge failure. Bench-scale folding and brittle faulting have created more local problems. Some faults create large slope-scale wedge failures. These geological variations and the relative orientation/position of the excavation necessitated the definition of a total of 11 geotechnical domains, each with an individual pit slope design. The improved understanding of the geology and its impact on the rockmass behaviour will lead to improved blasting practices and steeper slope angles.
The Influence of the Methodology for Slopes Forming in Open Pit Mines on their Stability
IOP conference series, 2019
Open pit mines are frequently accumulating significant amounts of material in the form of dumping grounds, landfills or forming land for reclamation. Often the form of emerging dumping grounds is determined by stability analysis of their slopes at the design stage. During the operation of the mining site and the collection of material on the pile, only the geometry of the slope is a subject of control. In many cases, after making slopes of a dozen or so meters height or even up to several tens of meters, and after a certain time has elapsed since their formation, deformation of the escarpments can be observed. At this stage, the only option is to change the geometry, i.e. inclination of a slope or, in the worst case, rebuilding of the dump. In the paper the analysis of the impact of the method of forming slopes and material quality on stability of formed slopes and their safe exploitation has been presented. It also presents a proposal to normalize the methodology of design and construction of slopes in a manner ensuring stability and taking into account the variability of the material parameters from which the slope is to be formed.
IOP Conference Series: Earth and Environmental Science
Batu Hijau is a gold mine which is now run and managed by PT Amman Mineral Nusa Tenggara (PT AMNT) with open mining method. The located in Sekongkang District, West Sumbawa Regency-West Nusa Tenggara Province. The geological structure aspects are interesting as objects in this study, due to the condition is very tight and become to trigger for the slope failure. Slope stability is one of the important terms for supporting in open pit mining activities. One of the slope failure indication is the failure caused by the structure. Geological structure analysis performed with kinematic analysis which takes into account the probability of failure and type of failure. The probability of Failure can count by structure orientation, the orientation of the mine slope design, and friction angle with using dips 6 software. The percentage of slide obtained from the ratio between the critical point from the critical zone with the total critical point in stereographic projection. The count applied in all geotechnics domain with inputting of parameter structure orientation, the orientation of the mine slope design, and friction angle. The result shows between 0% to 2.63% of planar failure. The percentages show probability of failure but still in the safe category with 10% safety limit. Slope safety factor counts manually based on the mathematical formula applied to all domains in Batu Hijau Open Pit Mining. The result shows the value between 1.04 to 1.905 on planar failure. This value shows the condition of slope in the research site is stable.