Bench Stability Research Articles

Верификация структурно-тектонического строения массива карьера «Нежданинское»

The article analyses the studies of factors affecting bench stability in the Nezhdaninskoye open-pit mine. It is determined that the fundamental factors are the vector location and characteristics of faults and cracks in the rock massif. The following three main systems of extended block-forming fractures were defined: (1) subvertical fractures with strike azimuth A = 290°; (2) fractures with strike azimuth A = 50° and dip angle into the massif P = 70°; (3) fractures with strike azimuth A = 50° and dip angle into the pit P = 40°. Basically, the extended surfaces of the rock massif discontinuities lie at an angle of 40-50° towards the mined-out space of the open pit. Individual extended fractures have the angle of 60-65°. The most probable fracture systems involved in bench collapse in case of unfavourable combination of the slope direction and the fracture system's dip are traced in the south-eastern walls of the open pits. There are no unfavourable surfaces in the northern and north-western walls. At the same time, faults running parallel to the benches create potential collapse zones, which requires additional measures to ensure their stability. The structural and tectonic framework of the rock massif has a significant impact on the formation and stability of the open-pit benches. Taking these factors into account when planning and developing open-pit mines will help ensure occupational safety and high efficiency of the mining process.

Bench Stability Design Based on SMR, Q-Slope, Block Theory and Kinematic Analysis

Bench Stability Design Based on SMR, Q-Slope, Block Theory and Kinematic Analysis

Catalytic One‐Pot Reductive Amination of Carboxylic Acids

AbstractThe broad applications of primary alkyl amines in various fields have spurred extensive interests in synthetic organic chemistry. Recently, the reductive amination of carboxylic acids has become an attractive and practical strategy for synthesizing primary alkyl amines, due to their wide availability and bench stability. However, the inherent stability and higher oxidation state of carboxylic acids render this new strategy with new challenges. This Concept provides a summary of the recent advancements in the reductive aminations of carboxylic acids, specifically focusing on the catalytic tactics, underlying mechanisms, and applications in the synthesis of valuable products.

Влияние статической нагрузки от горнотранспортного оборудования на устойчивость уступов, расположенных в скальных породах

Most of the enterprises applying open-pit mining method at deposits face challenges of pit wall steepening when approaching the pit wall to the final position or reducing productivity. The main task when increasing the angle of pit slope is to determine its stability. One of the ways to steepen the open-pit wall is to increase the slope angle of benches composing the open-pit wall. The bench stability is primarily determined by its physical properties and structural uncertainty. The higher the strength properties of rocks, the steeper the slope angle formed in these rocks can be. The "Rules of stability..." provide for the possible accounting the loads from mining equipment when assessing the stability, but this possibility is provided for the calculation of bench stability of open-pits and cuts, formed by semi-hard and dispersed rocks, dumps formed from clay or semi-hard rocks and (or) from a mixture of clay and hard rocks. At the same time, it is of interest to assess the impact of static loading from the located mining transport equipment in a stationary state on the stability of the benches located in hard rocks. It is shown that the load from the track dozer scraping the berms has an impact of no more than 6-7% for a distance of about 15 m from the top crest of a 30-meter long bench with a slope angle of 80° to the edge of the track, which is generally insignificant for maintaining bench stability. The minimum value of the safety factor of the bench with the load from the BELAZ-75306 mining dump truck is at a distance of 8 to 10 m from the top crest to the edge of the wheel. That is, at this distance the mining dump truck has the maximum impact. At 30 m distance from the bench’s top crest, mining dump truck has no impact on the bench stability. The maximum impact of the dump truck on the stability is 22 to 25%.

Studying rock mass jointing to provide bench stability while Northern Katpar deposit developing in Kazakhstan

Purpose is to identify the basic joint systems, their characteristics, distribution within the rock mass, and determine impact of the joints on the bench stability. Methods. The risks of strain emergence in the form of blocks sliding along weakness surfaces within the local areas were determined based upon the definition of rock stability loss. The results of large-scale measurements of jointing were processed using circular and bar diagrams as well as stereographic grids. In the context of the paper, kinematic analysis was implemented through Dips Rocscience Inc. Software. Findings. Five basic joint systems have been identified; joints of 2nd and 5th systems are the most commonly encountered among them. The results of the jointing determination within the open pit boundaries have been represented as well as the open pit wall stability in terms of each site inclusive of consideration of potential strains along the sliding surface. Originality. For the first time, zoning of the open pit wall in terms of slide types has been performed. It has been identified that potential shear of a prismatic block is 33%; at the same time, 66% are bench destruction with the block toppling. The risk of wedge-shaped block shear is minimal. Practical implications. The research findings may be helpful to define and select both parameters and conditions of safe mineral extraction under the specific mining and geological conditions. In turn, the abovementioned will help reduce the risk of accidence while providing scientifically substantiated approach to select quarrying sequence, techniques, and system.

A 3D nearfield vibration model for simultaneous blasting of multiple holes in the sedimentary rock formation.

Blasting is the most common excavation techniques for sedimentary rocks especially for sandstone. However, blasting process leads to unwanted breakage in the rock beyond the desired perimeter of excavation and such breakage is called blast-induced rock damage or ‘backbreak’. In surface blasting, ‘backbreak’ impacts on bench stability, excavator operation and drilling in the new face. However, prior estimation of extent of rock breakage zone can provide an idea to formulate the blast design to control the backbreak. In the estimation of blast-induced damage zones, vibration-based prediction techniques are one of the popular choices due to their easy applicability in varying geotechnical conditions. The existing vibration-based models are mostly one dimensional and estimate the damage zone only for the single blasthole. However, practically more than one blast holes are blasted to match the production requirement. Sometimes due to improper delay sequence or by using detonating fuse as surface connection, more than one blastholes are blasted simultaneously. Thus, in this study, a damage estimation model is developed based on vibration theory, which can estimate the damage zone generated due to the blasting of multiple holes simultaneously. This model is a three-dimensional model, which considers the position of the blast holes, charges and point of damage in a 3D space. The model is tested in sandstone rock through four numbers of single row multiple holes blastrounds. It is found that the model is predicting damage zone with an accuracy of ± 12%.

One-Pot Synthesis of Strain-Release Reagents from Methyl Sulfones.

Sulfone-substituted bicyclo[1.1.0]butanes and housanes have found widespread application in organic synthesis due to their bench stability and high reactivity in strain-releasing processes in the presence of nucleophiles or radical species. Despite their increasing utility, their preparation typically requires multiple steps in low overall yield. In this work, we report an expedient and general one-pot procedure for the synthesis of 1-sulfonylbicyclo[1.1.0]butanes from readily available methyl sulfones and inexpensive epichlorohydrin via the dialkylmagnesium-mediated formation of 3-sulfonylcyclobutanol intermediates. Furthermore, the process was extended to the formation of 1-sulfonylbicyclo[2.1.0]pentane (housane) analogues when 4-chloro-1,2-epoxybutane was used as the electrophile instead of epichlorohydrin. Both procedures could be applied on a gram scale with similar efficiency and are shown to be fully stereospecific in the case of housanes when an enantiopure epoxide was employed, leading to a streamlined access to highly valuable optically active strain-release reagents.

An international collaborative study to assign value for Total Factor XIII‐B Subunit Antigen to the WHO 1st International Standard for Factor XIII Plasma, (02/206): Communication from the ISTH SSC Subcommittee on Factor XIII and Fibrinogen

BackgroundFactor XIII (FXIII)‐B subunit measurements are required for the diagnosis and characterization of the type of FXIII deficiency. Furthermore, therapy for FXIII‐A deficiency with recombinant FXIII (rFXIII‐A) relies on available FXIII‐B. ObjectiveTo carry out a collaborative study to calibrate and assign value to the current WHO 1st International Standard (IS) FXIII Plasma for Total FXIII‐B subunit, relative to locally collected normal plasma pools. MethodsLaboratories were instructed to use a validated method (specific ELISA antibodies provided) for assessment of Total FXIII‐B subunit antigen potency. All laboratories used this method with one laboratory using an additional in‐house method. Nine data sets were received from seven laboratories (37 assays in total), which provided a total of 35 valid estimates for this new assignment. Total FXIII‐B subunit estimates were calculated relative to locally collected normal plasma pools, using an arbitrary value of 1.00 unit of Total FXIII‐B subunit per ml, for each pool. ResultsCombination of results produced an overall mean of 0.98 units/mL with an inter‐laboratory variability (geometric coefficients of variation – GCV%) of 18.3% [95% confidence interval: 0.86–1.11]. Real‐time and bench stability studies indicated good stability and preservation of the FXIII‐B subunit analyte in the WHO 1st IS FXIII Plasma (02/206). ConclusionFollowing agreement by study participants, ISTH/SSC Experts, WHO‐ISTH Liaison Group and the SSC Board, the WHO/ECBS established the current WHO 1st IS Factor XIII plasma (NIBSC code 02/206) by additionally assigning it with a Total FXIII‐B subunit antigen value of 0.98 IU/ampoule, in October 2019.

Protein Modification via Mild Photochemical Isomerization of Triazenes to Release Aryl Diazonium Ions.

This work describes the development of phenyl diazenyl piperidine triazene derivatives that can be activated to release aryl diazonium ions for labeling of proteins using light. These probes show marked bench stability at room temperature and can be photoisomerized via low-intensity UVA irradiation at physiological pH. Upon isomerization, the triazenes are rendered more basic and readily protonate to release reactive aryl diazonium ions. It was discovered that the intensity and duration of the UV light was essential to the observed diazonium ion reactivity in competition with the traditionally observed photolytic radical pathways. The combination of their synthetic efficiency coupled with their overall stability makes triazenes an attractive candidate for use in bioconjugation applications. Bioorthogonal handles on the triazenes are used to demonstrate the ease by which proteins can be modified.

Study of blasting effect on bench stability

The study of blast effect on bench stability is indispensable, because the overall stability of the quarry’s slope is directly linked to it. For this purpose, a study is conducted in a limestone quarry. Before the stability analysis, a fragmentation evaluation is carried out by two methods, by the Kuz-Ram model and the Digital Image analysis method using the WipFrag program, this part of the work aims to establish a more efficient blast design that assures a better fragmentation and a higher stability for the quarry’s structure. Afterwards, a numerical stability analysis approach is adopted, by employing the Finite Element Method (FEM) through the Phase2 software. A 2D numerical model of the quarry’s profile is constructed, on which simulations are carried out for two cases: 1-static conditions; 2-Dynamic conditions using the proposed blast design. This analysis goals are to define the possible deformation that the blasting process could engender to the benches and its effect on bench’s stability as an individual case and on the overall stability of the slope in general.

On-demand synthesis of phosphoramidites

Automated chemical synthesis of oligonucleotides is of fundamental importance for the production of primers for the polymerase chain reaction (PCR), for oligonucleotide-based drugs, and for numerous other medical and biotechnological applications. The highly optimised automised chemical oligonucleotide synthesis relies upon phosphoramidites as the phosphate precursors and one of the drawbacks of this technology is the poor bench stability of phosphoramidites. Here, we report on the development of an on-demand flow synthesis of phosphoramidites from their corresponding alcohols, which is accomplished with short reaction times, near-quantitative yields and without the need of purification before being submitted directly to automated oligonucleotide synthesis. Sterically hindered as well as redox unstable phosphoramidites are synthesised using this methodology and the subsequent couplings are near-quantitative for all substrates. The vision for this technology is direct integration into DNA synthesisers thereby omitting manual synthesis and storage of phosphoramidites.

Determination of bench, dump and road sliding wedge technological parameters

Mine surveying in mining operations is of particular importance, since all technological processes of the full life cycle of a mining enterprise and, ultimately, its competitiveness depend on the surveying quality, efficiency and reliability. Organizations independently determine the structure of mine surveying services, taking into account the methods applied and the scale of mining. To ensure safe open-pit mining of minerals, it is necessary to permanently assess and monitor the pit bench and wall rock mass condition. Misjudgement of rock physical and mechanical properties, non-observance of the minerals mining and transportation process cycle, changes in climatic conditions and other problems lead to loss of stability of rocks in all parts of an open pit, including in the areas of ore production and mining and transport equipment operation. The existing practice shows that the effectiveness of an open pit wall and bench stability calculation can be achieved using a technique that should take into account the slope deformation and failure mechanism, as well as the nature of the stress-strain state of the open pit rock mass. The studies presented in the paper are based on comparative analysis of the sliding wedge parameters for benches, dumps and roads at open pits using analytical and graphical software packages, and taking into account the static load produced by dump trucks. The study findings allow to establish that: determination of the bench slope stability and the sliding wedge width, performed by the analytical method, gives higher accuracy results than those obtained by the graphical method; the bench slope stability and the sliding wedge width depend not only on the rock physical and mechanical condition, but also on the bench height, the dump truck (plus its freight load) weight per 1 linear meter of the placement area, the distance from the slope edge and other factors; the rock mass is stable and not subject to landslide phenomena for as long as the sum of the holding forces is greater than or equal to the sum of the shearing forces; when using large-sized transport equipment of nonstandard weight in open-pit mining, it is necessary to calculate the safe width of the sliding wedges, taking into account the loads on them (per 1 linear meter), the values of which can be 1.5–2.0 times higher than those calculated for the circular-cylindrical sliding surface.

General concept of determining the parameters of non-mining walls of ultra-deep diamond deposits development open pits

A specific feature of open pit mining of diamond deposits in Western Yakutia is the construction of the open pits in the zone of negative ambient temperatures, which includes thick permafrost rock mass, and which is at the same time complicated by the influence of cryogenic processes on deformation of pit wall benches. The paper presents the comparative analysis of strength characteristics in frozen and thawed rocks, stability of benches during mining, the general geomechanical approach to the determination of parameters of non-mining walls of the ultra-deep open pit diamond mines, and the parameters of nonmining walls and benches. Optimization of open pit wall configuration should primarily be based on the maximum utilization of the strength properties of frozen rocks in combination with the development of new approaches, calculation schemes and methods for assessing stability of open pit walls and benches of unconventional design, including the non-mining vertical benches. The main design characteristic that determines the parameters of open pit walls is the structural tectonic relaxation coefficient, which specifies the calculated value of cohesion in rock mass. For the diamond deposits, the values of the structural relaxation coefficient were obtained in a series of field tests and back calculations. Full-scale tests were carried out both during exploration operations in underground mines and in open pits. The accuracy of determining the values of the structural relaxation coefficient in the range of 0.085–0.11 is confirmed by the parameters of non-mining walls in an open pit mine 385–640 m deep, with overall slope angles of 38–55° and a steeper H 0.35–0.5 lower part having the slope angle of up to 70° with average strength characteristics of 7.85–11.84 MPa and the internal friction angle of 28.1–37.4°. Using the natural load-bearing capacity of rock mass to the full advantage, which the values of the structural relaxation coefficient of deposits show, allows optimization of open pit wall slope design and minimization of stripping operations.

Implications of DFN Model Selection in Open Pit Bench Stability Analyses

A coupled Discrete Fracture Network (DFN) – Limit Equilibrium Analysis (LEA) approach to the design of bench face slopes in open pit mines has significant advantages over conventional analyses. The reliability of this approach is directly related to the quality of the input data and the ability for the generated DFN to adequately capture the characteristics of the rock mass. Different DFN model generators have specific input requirements and inherent assumptions. This paper addresses the critical issue of selecting an appropriate DFN model. Through a worked example, it illustrates the implications of selecting a series of different DFN models and generators on the stability analyses, and interpretation of the results. This is shown to have significant impact on the design of open pit slopes.

Predicting phosphirane air stability using density functional theory

AbstractPhosphorus 3‐membered heterocycles, phosphiranes, provide an interesting synthetic scaffold with a potentially diverse range of reactions that are currently underexplored. This is in part due to their difficulty in synthesis, with many products and intermediates containing low air stability. With the application and extension of a density functional theory (DFT) model to phosphiranes by calculation at the UB3LYP/6‐31G(d) level of their radical cation singly occupied molecular orbital (SOMO), a correlation between calculated and relative experimental air stability has been demonstrated. The model also accounts for the stability of many synthesised substituted and unsubstituted phosphiranes and has allowed new synthetic targets to be identified, in particular, 1‐(2,4,6‐tri‐tert‐butoxyphenyl)phosphirane exhibited high theoretical air stability. Because of the simplicity and efficiency of the model, its application enables phosphiranes to be screened for high bench stability, providing accessibility for their use in synthetic chemistry, in turn, realising the potential for incorporation of phosphiranes into complex synthetic strategies.

Prediction of Blast-Induced Ground Vibration in an Open-Pit Mine by a Novel Hybrid Model Based on Clustering and Artificial Neural Network

Ground vibration (PPV) is one of the hazard effects induced by blasting operations in open-pit mines, which can affect the surrounding structures, particularly the stability of benches and slopes in open-pit mines, and impact underground water, railway, highway, and puzzling for neighboring communities. Therefore, controlling, accurate prediction, and mitigating blast-induced PPV are necessary. This study contributed a new computational model in predicting blast-induced PPV for the science community and practical engineering with high accuracy level. In this study, a novel hybrid artificial intelligence model based on the hierarchical k-means clustering algorithm (HKM) and artificial neural network (ANN), namely a HKM–ANN model, was considered and proposed for predicting blast-caused PPV in open-pit mines. Accordingly, input data were first clustered by the HKM algorithm, and then, the ANN models were developed based on the obtained clusters. For this aim, 185 blasting events were collected and analyzed. A hybrid model based on fuzzy c-means clustering (FCM) and support vector regression (SVR), i.e., FCM–SVR model, which was proposed by previous authors was also applied for comparison of results with our proposed HKM–ANN model. In addition, an empirical method, several ANN and SVR models (without clustering), FCM–ANN, and HKM–SVR were developed for comparison purposes. For measuring the performance of the improved models, coefficient determination (R2), root-mean-square error, and variance account for were used as the performance indicators. The results show that the HKM algorithm played a significant role in improving the accuracy of the ANN models. The proposed HKM–ANN model was the most superior model in estimating PPV caused by blasting operations in this study.

Experimental and Theoretical Investigation of Structures, Stoichiometric Diversity, and Bench Stability of Cocrystals with a Volatile Halogen Bond Donor

We present a combined experimental and theoretical study of the structures and bench stability of halogen-bonded cocrystals involving the volatile halogen bond donor octafluoro-1,4-diiodobutane, with phenazine and acridine as acceptors. Cocrystallization experiments using mechanochemistry and solution crystallization revealed three chemically and structurally distinct cocrystals. Whereas only one cocrystal form has been observed with acridine, cocrystallization with phenazine led to two stoichiometrically different cocrystals, in which phenazine employs either one or two nitrogen atoms per molecule as halogen bond acceptor sites. Cocrystal stability was evaluated experimentally by simultaneous thermogravimetric analysis and differential thermal analysis or differential scanning calorimetry, real-time powder X-ray diffraction monitoring of cocrystals upon storage in open air, and theoretically by using dispersion-corrected periodic density functional theory. The use of real-time powder X-ray diffraction en...

Mechanochemistryvs.solution growth: striking differences in bench stability of a cimetidine salt based on a synthetic method

A mechanochemically prepared solvated salt of an archetypal blockbuster drug exhibits significantly different bench stability to analogous material made in solution.

Why 3D seismic data are an asset for exploration and mine planning? Velocity tomography of weakness zones in the Kevitsa Ni-Cu-PGE mine, northern Finland

Kevitsa is a disseminated Ni-Cu-PGE (platinum group elements) ore body in northern Finland, hosted by an extremely high-velocity ([Formula: see text]) ultramafic intrusion. It is currently being mined at a depth of approximately 100 m with open-pit mining. The estimated mine life is 20 years, with the final pit reaching a depth of 500–600 m. Based on a series of 2D seismic surveys and given the expected mine life, a high-resolution 3D seismic survey was justified and conducted in the winter of 2010. We evaluate earlier 3D reflection data processing results and complement that by the results of 3D first-arrival traveltime tomography. The combined results provide insights on the nature of some of the reflectors within the intrusion. In particular, a major discontinuity, a weakness zone, is delineated in the tomography results on the northern side of the planned pit. Supported by the reflection data, we estimate the discontinuity, likely a thrust sheet, to extend down approximately 600 m and laterally 1000 m. The weakness zone terminates prominent internal reflectivity of the Kevitsa intrusion, and it is associated with the extent of the economic mineralization. Together with other weakness zones, a couple of which are also revealed by the tomography study, the discontinuity forms a major wedge block that influences the mine bench stability on the northern side of the open pit and likely will cause more issues during the extraction of the ore in this part of the mine. We argue that 3D seismic data should routinely be acquired prior to commencement of mining activities to maximize exploration efficiency at depth and also to optimize mining as it continues toward depth. Three-dimensional seismic data over mineral exploration areas are valuable and can be revisited for different purposes but are difficult to impossible to acquire after mining has commenced.

Integral Pattern of Bench Stability on all Adjacent Rock Of Open-Pit Mine in Solid Rocks

Integral Pattern of Bench Stability on all Adjacent Rock Of Open-Pit Mine in Solid Rocks