Slope Stability Considerations in Integrated Surface Mine Design (original) (raw)
Related papers
Inter-ramp and bench design of open-pit mines: the Portage pit case study
Canadian Geotechnical Journal, 2011
Using a case study, this paper presents an integrated methodology for assessing structural slope stability at the inter-ramp and bench levels. Robust algorithms have been developed and implemented to compute, at inter-ramp and bench levels, slope orientations and slope stability using input data compatible with a commercially available mine-design software tool database structure. Multi-criteria stability analyses were performed based on various design criteria. Susceptibility maps were produced enabling the identification of zones of concern in the designed pit. The obtained results suggest that inter-ramp angles do not present instability concerns over the entire pit surface. At bench levels, potential instability zones were identified within two structural domains totalling 6% of the total pit surface.
Probabilistic assessment of slope stability at ore mining with steep layers in deep open pits
Mining of Mineral Deposits
Purpose. A methodology development for predicting the geomechanical situation when mining an ore deposit with steep-dipping layers, taking into account the uncertainty in determining the rock properties, which is a consequence of the rock mass heterogeneity. Methods. The assessment of the open-pit wall stability is based on a combination of numerical simulation of the rock stress-strain state (SSS) and probabilistic analysis. The finite element method is used to determine the changes in the SSS that occur at various stages of mining operations due to design changes in the overall open-pit slope angle. The elastic-plastic model of the medium and the Mohr-Coulomb failure criterion are implemented in the codes of the 3D finite element analysis program RS3 (Rocscience). Stochastic simulation is used to assess random risks associated with natural object state variations. Findings. The distribution of maximum shear strains, which localizes the real or potential sliding surfaces in the ope...
Journal of Mining and Environment, 2018
Slope stability analysis is one of the most important problems in mining and geotechnical engineering. Ignoring the importance of these problems can lead to significant losses. Selecting an appropriate method to analyze the slope stability requires a proper understanding of how different factors influence the outputs of the analyses. This paper evaluates the effects of considering the real geometry, changes in the mesh size, and steepness of the slope, as the dimensional effects, and changes in the geomechanical parameters, as the media effects on the global slope stability of an open-pit mine using finite difference methods with a strength reduction technique. The case study is the Tectonic Block I in the old pit (steep slope) and the redesigned new pit (gentle slope) of the Choghart iron mine. In the first step, a series of 2D and 3D slope stability analyses are performed and compared in terms of safety and potential failure surface. The results obtained show that by considering t...
Pit Slope Configuration for Open Pit Mining – A Case Study
American journal of science, engineering and technology, 2024
To achieve stable pit wall slopes, it is imperative to obtain a fair knowledge of the rock mass characterisation before designing the pit. Insufficient knowledge of the competency of the country rock could lead to using unsupported slope configuration in the design process which can consequently lead to slope failure. In this study, the geomechnical properties of the Bremen-Nkosuo concession are analysed using Bieniawski's classification scheme to determine the Rock Mass Rating (RMR) for defining safe pit slope configuration of the Nkosuo pit. The findings show that the rockmass are best described as 'fair' for the two main lithologies existing at the concession. Subsequently, localised adjustment factors are applied to the calculated RMR to arrive at Mining Rock Mass Ratings (MRMR). These MRMR values are correlated with 50 m fixed stack height and 1.2 safety factor to determine optimum Bench Slack Angle (BSA) of 54° and 57° for host sedimentary and granitic rocks respectively. For individual benches, optimum slope design configurations were 10 m, 800, and 6.6 m respectively for bench height, bench face angle and catch berm for metasedimentary rocks. Likewise, that for granitic formation were 10 m bench height, 800 face angle and 6.0 m catch berm width. These configurations are in conformance with mineral and mining regulations of Ghana. Slope stability assessment was performed which included Slope Mass Rating (SMR), Kinematic and Limit equilibrium analysis. From the analysis, multi-bench scale slope instability occurrence was found to be rare but single-double scale could be possible at the western wall of the planned pit with probability of failure of about 0.4. Presplit and trim shots perimeter blasting techniques are recommended to maintain the integrity of the final pit walls at certain areas.
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.
Journal of China University of Mining and Technology, 2008
One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador-Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a geotechnical map was prepared. Then, the value of MRMR (Mining Rock Mass Rating) was determined for each zone. Owing to the fact that the Chador-Malu iron ore mine is located in a highly tectonic area and the rock mass completely crushed, the Hoek-Brown failure criterion was found suitable to estimate geo-mechanical parameters. After that, the value of cohesion (c) and friction angle ( ) were calculated for different geotechnical zones and relative graphs and equations were derived as a function of slope height. The stability analyses using numerical and limit equilibrium methods showed that some instability problems might occur by increasing the slope height. Therefore, stable slopes for each geotechnical zone and prepared sections were calculated and presented as a function of slope height.
REM - International Engineering Journal
The traditionally and widely used Lerchs-Grossmann algorithm presents wellknown limitations that newer propositions attempt to overcome. The direct block schedule (DBS) methodology, which has gained relevance with computational advances, obtains the final pit as a natural result of production sequencing, different from Lerchs-Grossmann-based algorithms. This process flow applies constraints in the final pit definition stage attempting to provide a more realistic result and to minimize risks. Slope instability is a common and inherent risk to open pit mining and may affect the project's net present value (NPV). A study of the impacts of slope angle variations on safety indexes and final pit NPV provides an auxiliary tool for the overall slope angle definition process. This article presents a case study in which the effects of variations of the overall slope angle on the safety factor (SF) and project NPV were analyzed. A total of 25 pits were generated by each studied final pit definition methodology, and each pit had the sections with the varied slope angles analyzed in the stability assessment, resulting in a total of 150 slopes analyzed. A comparison between the results obtained by the two different methodologies implemented in commercial software is presented. The results show no relationship between the NPV and the overall slope angle using the DBS methodology. An analysis of the results for each geotechnical sector obtained by the traditional methodology was conducted and may contribute to the trade-off analysis between the best slope angle to achieve a reasonable SF and the maximum NPV.
SSIM 2021: Second International Slope Stability in Mining, 2021
The challenges of representing geotechnical failure mechanisms in software is being gradually addressed as search algorithms and computing power advance, especially to deal with complex anisotropic rock masses in which failure mechanisms are commonly three-dimensional (3D). This paper presents a case study of an iron ore mine with highly anisotropic rock mass strength that has been back-analysed using 3D limit equilibrium analysis methods. In order to provide as realistic model inputs as possible, field characterisation data and the reconstruction of the failed surface were used, as well as the material properties available from laboratory tests or bibliographic references. A probabilistic approach was applied to the initial parameters, resulting in a series of stochastic simulations that provided scenarios for the failure moment, when the Factor of Safety achieved close to 1.0. Then, based on the knowledge of the local geological-geotechnical context and failure mechanisms, a range of values for the geomechanical parameters were achieved to enhance the constitutive model of the rock mass.