scholarly journals Fall of Ground Management Through Underground Joint Mapping: Shallow Chrome Mining Case Study

2021 ◽  
Author(s):  
Vhutali Netshilaphala ◽  
Tawanda Zvarivadza
Keyword(s):  
Probabilistic Analysis ◽  
Underground Mining ◽  
Jointed Rock ◽  
Rock Falls ◽  
Support Design ◽  
The North ◽  
Geological Discontinuities ◽  
Joint Mapping ◽  
Mapping Techniques ◽  
Stability Enhancement

Abstract Joint properties and useful mapping techniques are key to the fall of ground management in underground mining. The study analysed the fall of ground management techniques at the mine with a view to identify the causal factors of the falls of ground. This paper practically demonstrates how two mapping techniques were used to obtain joint data. A brief description of geological discontinuities at the study area is given in the paper. Joint mapping was carried out in both the North and South sections of the mine. Procedures followed when collecting joint data are also provided. The collected joint data was used to evaluate rock fall probability. Rockfall probabilistic analysis carried out in the study indicates that about 80% of all key blocks formed are 1m3 in size. Results show that larger blocks are more likely to fail through the rotation. Furthermore, to prevent small blocks from falling between support units, areal coverage is suggested in heavily jointed rock masses. Probabilistic analysis can be used to evaluate the probability of rock falls, and support design for stability enhancement. The research noted that at the centre of effective falls of ground management are accurate and precise structural/joint mapping. This research is part of an MSc Engineering study.

scholarly journals Automatic Monitoring System Designed for Controlling the Stability of Underground Excavation

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Piotr MAŁKOWSKI ◽  
Zbigniew NIEDBALSKI ◽  
Łukasz BEDNAREK
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Automatic Monitoring ◽  
Mass Movements ◽  
Support Design ◽  
Automatic Monitoring System ◽  
Underground Workings ◽  
The Stability ◽  
Technical Solutions ◽  
The Given

Ensuring the stability of mining excavations is a crucial aspect of underground mining. For thispurpose, appropriate shapes, dimensions, and support of workings are designed for the given mining andgeological conditions. However, for the proper assessment of the adequacy of the used technical solutions,and the calibration of the models used in the support design, it is necessary to monitor the behavior of theexcavation. It should apply to the rock mass and the support. The paper presents the automatic systemdesigned for underground workings monitoring, and the example of its use in the heading. Electronicdevices that measure the rock mass movements in the roof, the load on the standing support, and on bolts,the stress in the rock mass, are connected to the datalogger and can collect data for a long of time withoutany maintenance, also in hard-to-reach places. This feature enables the system to be widely used, inparticular, in excavations in the vicinity of exploitation, goafs, or in the area of a liquidated exploitationfield.

scholarly journals Factors Influencing Ore Recovery and Unplanned Dilution in Sublevel Open Stopes. Case study of Shaft No.4 at Konkola Mine, Zambia

2020 ◽  
Vol Special Issue (1) ◽  
Author(s):  
Kalunga Ngoma ◽  
Victor Mutambo
Keyword(s):  
Numerical Modelling ◽  
Principal Stress ◽  
Underground Mining ◽  
Poisson Ratio ◽  
High Stress ◽  
Geological Strength Index ◽  
Total Displacement ◽  
Ground Conditions ◽  
Geological Discontinuities ◽  
Major Principal Stress

Konkola Copper Mine’s Number 4 Shaft is a trackless underground mine applying sublevel open stoping (SLOS) mining method. Number 4 shaft wants to increase ore production from 1 million metric tonnes per annum to 3 million metric tonnes per annum in the next 5 years but ore recovery is 70% or less and dilution is 20% or more. In order to achieve the desired annual target of 3 million metric tonnes ore recovery should be increased from70% to (≥85%) and dilution should be reduced from 20% to (≤10%). Despite being one of the most used underground mining methods, the current SLOS has a challenge of high unplanned dilution. This paper reviews and evaluates parameters that influence recovery and unplanned dilution in sublevel open stopes and applies numerical modelling using PHASE2 software to establish the influence of stress environment on unplanned dilution at the mine. The input parameters for numerical modelling were: Uniaxial Compressive strength (UCS=170MPa), Geological Strength Index (GSI) =55, Young’s Modulus (E) =26000MPa, Hoek-Brown constant (s) =0.0067, Hoek-Brown constant (mi) =20 and Poisson ratio (v) =0.2 major principal stress (σ1) 39MPa, intermediate stress (σ2= 18MPa) and the minor principal stress (σ3= 15MPa). Results obtained from review of mine production records indicate that the main factors that influence unplanned dilution at Number 4 shaft are: poor ground conditions, lack of compliance to recommended stope designs, poor drilling and blasting practices, presence of geological discontinuities, adopted mining sequence of extracting high ore grade first that leads to creation of high stress blocks within the orebody and delayed mucking practice. Results obtained from PHASE 2D model indicate that total displacement of 90mm is recorded in the hangingwall hence influencing stope wall instability that leads to increased unplanned dilution. After stope extraction, it was observed that 60MPa of induced stress developed at the top right corner and 45-50 MPa at the crown pillar and right bottom corner of the stope.

Analisys of mud inrush water sources into underground working of the Sokolovskoe ore deposit

2020 ◽  
pp. 56-67
Author(s):  
E. Yu. Efremov
Keyword(s):  
Hydraulic Conductivity ◽  
Large Scale ◽  
Underground Mining ◽  
Temporal Distribution ◽  
High Water ◽  
The North ◽  
Initial Block ◽  
Groundwater Supply ◽  
Spatio Temporal ◽  
Inrush Water

There is a serious threat of groundwater inrush from overlying sedimentary layers for underground mining. When ore is extracted using block caving method, the area of overburden collapse over ore zone disrupts the natural structure of high hydraulic-conductivity and low hydraulic-conductivity layers. This process creates conditions for the accumulation and transfer of groundwater to mine workings, which lead to accidents, up to disastrous proportions. The research aim is to determine the spatio-temporal distribution of mud inrushes, and to identify groundwater supply sources of inrushes to reduce the geotechnical risks of underground mining in Sokolovskaya mine. Research methods include localization, classification, and analysis of monitoring data, comparison of mud inrushes distribution with geostatistical parameters of the main aquifers.The majority of large-scale accidents caused by mud inrushes are confined to the central and northern area of caved rock zone. The most risky stage of the ore body extraction is the initial block at the lower extraction level. The sources of water supply for the majority of the mud inrushes are high water level areas of the Cretaceous aquifer to the north and west of the mine. Rational targeted drainage aimed at draining the identified areas of the aquifer is the best way to reduce the risk of accidents.

scholarly journals Interaction of Natural and Technical Systems in the Subsoil Development Areas

2019 ◽  
Author(s):  
В.И. Голик ◽  
Х.Х. Кожиев ◽  
О.Г. Бурдзиева ◽  
С.А. Масленников
Keyword(s):  
Strain Gauge ◽  
Underground Mining ◽  
Economic Effect ◽  
The State ◽  
Economic Effects ◽  
Raw Material ◽  
The North ◽  
Ore Body ◽  
Technology Improvement ◽  
River Valleys

Деятельность горнодобывающей отрасли осуществляется с высокой степенью риска. Проблема управления состоянием массива особо актуальна в условиях горного региона с неработающими выработками, воронками провалов и отвалами пород и хвостов обогащения на террасных участках и в долинах рек. Она особо актуальна в условиях региона Северная Осетия с неработающими выработками, воронками провалов и отвалами пород и хвостов обогащения на террасных участках и в долинах рек. Увеличение глубины горных работ и объемов выемки сырья в сейсмически активных районах усиливают статическое и динамическое воздействие на геомеханические системы. Одним из способов исследования динамики напряжений в массиве являются измерения с помощью тензометрических датчиков. На одном из месторождений была оборудована замерная тензометрическая станция. Полученные эпюры напряжений вокруг выработки служили основанием для оценки поведения массива. Установлено, что изменение состояния крепи в зависимости от фазы развития очистных работ подчиняется закономерности. Пока рудное тело в пределах блока ведет себя как защемленная в висячем и лежачем боках балка, напряжения распределяются равномерно. После отрезки рудного тела со стороны висячего бока нагрузка на верхний элемент крепи со стороны очистных работ возрастает. Одним из направлений совершенствования технологий является использование феномена заклинивания дискретных пород, что нередко позволяет обеспечить возможность отработки месторождений с получением экологоэкономического эффекта при обеспечении безопасности горных работ. Эффективность использования породных конструкций складывается из экономии труда и материалов на управление состоянием скальных массивов при подземных работах. Оптимизация влияния напряжений в зоне взаимодействия очистных и подготовительных выработок уменьшает разубоживание руд породами и снижает опасность травмирования работающих отлаивающимися породами. При подземной разработке скальных сложноструктурных металлических месторождений в зоне взаимодействия горных выработок величина и знак напряжений во времени и пространстве может быть прогнозирована с достаточной для оперативного управления детализацией. Учет геомеханических факторов при отработке таких участков позволяет корректировать параметры разработки с получением экономического эффекта от повышения качества добываемых руд и уменьшения опасности для работающих. Mining activities are carried out with a high degree of risk. The problem of managing the state of the massif is especially relevant in the conditions of a mountainous region with idle workings, funnel dips and dumps of rocks and tailings in terraced areas and in river valleys. It is especially relevant in the conditions of the North Ossetia region with idle workings, funnel dips and dumps of rocks and tailings in terraced areas and in river valleys. An increase in the depth of mining and volumes of raw material excavation in seismically active areas reinforce the static and dynamic effects on geomechanical systems. One of the methods for studying the dynamics of stresses in an array is measurements using strain gauge sensors. At one of the fields, a metering strain gauge station was equipped. The obtained stress diagrams around the working served as the basis for assessing the behavior of the array. It was established that the change in the state of the lining, depending on the phase of development of the treatment works, is subject to regularities. While the ore body within the block behaves like a beam pinched in the hanging and lying sides, the stresses are distributed evenly. After segments of the ore body from the side of the hanging side, the load on the upper support element from the side of the treatment works increases. One of the areas of technology improvement is the use of the phenomenon of jamming of discrete rocks, which often allows you to provide the opportunity to develop deposits with environmental and economic effects while ensuring the safety of mining. The efficiency of using rock structures consists of saving labor and materials on managing the state of rock masses during underground work. Optimization of the effect of stresses in the zone of interaction between treatment and preparatory workings reduces ore dilution by rocks and reduces the risk of injury to workers using exfoliated rocks. In underground mining of rocky complex structural metal deposits in the interaction zone of mine workings, the magnitude and sign of stresses in time and space can be predicted with sufficient detail for operational control. Consideration of geomechanical factors when mining such sites allows you to adjust the development parameters to obtain the economic effect of improving the quality of ore mined and reducing the risk to workers.

scholarly journals Conditions and triggers of landslides on flysch slopes in Istria, Croatia

2020 ◽  
Vol 40 (2) ◽  
pp. 77-87 ◽  
Author(s):  
Josip Rubinić ◽  
Željko Arbanas ◽  
Sanja Dugonjić Jovančević
Keyword(s):  
Early Spring ◽  
Water Levels ◽  
Rock Falls ◽  
Landslide Occurrence ◽  
The North ◽  
Rainfall Trends ◽  
Geological Conditions ◽  
North Eastern ◽  
North Eastern Part ◽  
Sliding Zone

The paper gives a review of conditions and triggers in which landslides occur on flysch slopes in central and northern Istria. The north-eastern part of the Istrian Peninsula, the so-called Gray Istria, consists of Paleogene flysch rock mass. Landslides in this area are usually triggered by heavy rainfall together with human activity which changes slope geometry and assists in retaining surface water in the sliding zone. Briefly, hydrogeological conditions in combination with ground water levels and pore water pressures increase, lead to numerous instability phenomena, during the long and continuous rainfall periods. Instabilities usually include small rotational and translational landslides, and it is seldom that debris flows and rock falls occur. Landslides are evenly evidenced in the first part of winter and the early spring time which corresponds to the second rainfall peak. The analyses performed based on landslide documentation and rainfall historical data, show rainfall trends associated with landslide occurrence. Depending on meteorological, hydrological and geological conditions, cumulative rainfall which triggered landslide activation varies inside a three-month period. The results presented show rainfall trends which serve as characteristic landslide triggers on flysch slopes in north-eastern part of Istria.

Probabilistic Analysis of Extreme Riser Responses for a Weather-Vaning FPSO in Tropical Cyclones

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Curtis Armstrong ◽  
Yuriy Drobyshevksi ◽  
Christopher Chin ◽  
Irene Penesis
Keyword(s):  
Tropical Cyclones ◽  
Probabilistic Analysis ◽  
Probability Distributions ◽  
Statistical Properties ◽  
Flexible Riser ◽  
Response Distribution ◽  
The North ◽  
The North Sea ◽  
Flexible Risers ◽  
Extreme Responses

The probability distributions of extreme responses of a flexible riser connected to a weather-vaning floating production storage and offloading (FPSO) are developed and investigated numerically for two tropical cyclones. Statistical properties of riser responses provide the foundation for response based analysis (RBA), a comprehensive approach for the prediction of extreme responses and design metocean conditions of offshore systems. The storm-based probabilistic analysis is applied to responses of flexible risers with the objective to develop their distributions in a storm and to determine their most probable maximum (MPM) values. An asymptotic form of the response distribution in a storm is formulated, which can be used in the random event, method of Tromans and Vandersohuren (1995, “Response Based Design Conditions in the North Sea: Application of a New Method,” Offshore Technology Conference, Houston, TX, May 1–4). The methodology is illustrated by two case studies for an FPSO in cyclonic storms at a location offshore Australia. Time domain simulations are employed to predict the FPSO motions, critical riser responses, and their probability distributions. It is shown that the maximum storm responses can be reproduced by governing “equivalent” metocean intervals with increased percentiles or inflated durations. Effects of different environmental excitation upon the risers and their impact on the statistical properties of responses are discussed, providing important insights for extension toward a multistorm RBA approach. The study also discusses issues with practices such as the analysis for a 3 h design event and presents observations on the variability of several types of responses, which reveal their environmental sensitivities.

scholarly journals A Model of Anisotropic Property of Seepage and Stress for Jointed Rock Mass

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Pei-tao Wang ◽  
Tian-hong Yang ◽  
Tao Xu ◽  
Qing-lei Yu ◽  
Hong-lei Liu
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Underground Mining ◽  
Principal Direction ◽  
Water Pressure ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Metal Mine ◽  
Roadway Stability

Joints often have important effects on seepage and elastic properties of jointed rock mass and therefore on the rock slope stability. In the present paper, a model for discrete jointed network is established using contact-free measurement technique and geometrical statistic method. A coupled mathematical model for characterizing anisotropic permeability tensor and stress tensor was presented and finally introduced to a finite element model. A case study of roadway stability at the Heishan Metal Mine in Hebei Province, China, was performed to investigate the influence of joints orientation on the anisotropic properties of seepage and elasticity of the surrounding rock mass around roadways in underground mining. In this work, the influence of the principal direction of the mechanical properties of the rock mass on associated stress field, seepage field, and damage zone of the surrounding rock mass was numerically studied. The numerical simulations indicate that flow velocity, water pressure, and stress field are greatly dependent on the principal direction of joint planes. It is found that the principal direction of joints is the most important factor controlling the failure mode of the surrounding rock mass around roadways.

scholarly journals Autonomous Loading System for Load-Haul-Dump (LHD) Machines Used in Underground Mining

2021 ◽  
Vol 11 (18) ◽  
pp. 8718
Author(s):  
Carlos Tampier ◽  
Mauricio Mascaró ◽  
Javier Ruiz-del-Solar
Keyword(s):  
Underground Mining ◽  
Real Data ◽  
Production Environment ◽  
Rock Interaction ◽  
Rock Pile ◽  
The North ◽  
Loading System ◽  
Real Size ◽  
Human Operators ◽  
Two Stages

This paper describes an autonomous loading system for load-haul-dump (LHD) machines used in underground mining. The loading of fragmented rocks from draw points is a complex task due to many factors including: bucket-rock interaction forces that are difficult to model, humidity that increases cohesion forces, and the possible presence of boulders. The proposed system is designed to integrate all the relevant tasks required for ore loading: rock pile identification, LHD positioning in front of the ore pile, charging and excavating into the ore pile, pull back and payload weighing. The system follows the shared autonomy paradigm: given that the loading process may not be completed autonomously in some cases, it takes into account that the machine/agent can detect this situation and ask a human operator for assistance. The most novel component of the proposed autonomous loading system is the excavation algorithm, and the disclosure of the results obtained from its application in a real underground production environment. The excavation method is based on the way that human operators excavate: while excavating, the bucket is tilted intermittently in order to penetrate the material, and the boom of the LHD is lifted on demand to prevent or correct wheel skidding. Wheel skidding is detected with a patented method that uses LIDAR-based odometry and internal measurements of the LHD. While a complete loading system was designed, the validation had to be divided in two stages. One stage included the rock pile identification and positioning, and the other included the charging, excavation, pull back, and weighting processes. The stage concerning the excavation algorithm was validated using full-scale experiments with a real-size LHD in an underground copper mine in the north of Chile, while the stage concerning the rock pile identification was later validated using real data. The tests showed that the excavation algorithm is able to load the material with an average of 90% bucket fill factor using between three and four attempts (professional human operators required between two and three loading attempts in this mine).

scholarly journals Peningkatan Kestabilan Pilar Tambang Bawah Tanah Marmer di PT Gunung Marmer Raya

2020 ◽  
Vol 3 (1) ◽  
pp. 27-38
Author(s):  
Purwanto Purwanto
Keyword(s):  
Rock Mass ◽  
Safety Factor ◽  
Underground Mining ◽  
Underground Mine ◽  
Joint Movement ◽  
Pillar Stability ◽  
The North ◽  
Joint Monitoring ◽  
The Stability ◽  
Q System

PT Gunung Marmer Raya  (PT GMR), a room and pillar underground marble mining is located about  73 km to the north from Makassar, in Desa Tabo-Tabo, Kecamatan Bungoro, Kabupaten Pangkep. In the mining location, discontinuities are found as joint structure across the production area. The purpose of this service is to make pillar redesign that can improve the stability of underground mine. These activities start with field observation, determining the rock characteristic through sample testing in the laboratory, classifying the rock mass using Q-system method, up to redesigning a form of implementation to increase the stability of the marble underground mine. According to calculation of rock mass classification using Q-System, the recommended buffering is systematic bolting and fiber reinforced sprayed concrete as thick as 5-6 cm with spacing between bolts of 2.2 meters, or systematic bolting without concrete layering with spacing between-bolt 1.8 meter. Joint monitoring, especially on pillars, need to be done routinely so joint movement could be anticipated for progressive movement. The existing dimensions of pillar 5 m x 5 m in length and width is not recommended due to the safety factor is under 1,0  (unstable condition). Based on observation and analytic calculation, for each pillar height of up to 11 meters the pillar is recommended to redesign with length and width 5 m x 9 m for the chain pillar (safety factor around 1.35-1.49); and 5 m x 12 m for barrier pillars (safety factor around 1.58-1.74). Key Words: Underground mining; room and pillar method; Q-system classification system; pillar stability; marble mining.

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