فهرست مطالب

Journal of Mining and Environement
Volume:14 Issue: 4, Autumn 2023

  • تاریخ انتشار: 1402/07/09
  • تعداد عناوین: 20
  • Ahmed Abdelhalim, Islam Abuelella, Shawky Sakran, Said Said * Pages 1037-1059

    Kharit basin is an interior Cretaceous rift basin hosted in a Precambrian basement complex of the Arabian-Nubian shield. Satellite images and potential geophysical data previously outlined the basin without a detailed field study. Kharit area is a remote and hyper-arid area; therefore, the application of remote sensing is essential for completing the process of its geo-structural mapping. A multi-spectral optical dataset of the Landsat-8 and high-resolution images of Google Earth was integrated with the field investigation to classify the lithological units and define structures. That integration between analyzed satellite images and field investigations led to a geological map of a minimum scale of 1:50,000 for the lithological rock units and a maximum scale of up to 1:7000 for the structural mapping. The map shows an elongated NW-oriented rift basin filled by a thick deposit of Cretaceous sequences bounded from the east, west, and south by Proterozoic igneous and metamorphic rocks. Additionally, rift-related volcanic rocks were mapped along the western border fault system of the basin. The main mapped faults were delineated in three trends, NW-SE, WNW-ENE, and N-S, while several folds of NW orientations are developed as a normal drag of the main bounding faults. The Early Cretaceous extension along inherited Precambrian lineaments propagated this fault pattern and its associated folds. These structural elements configured the studied area architecture as several grabens with thick Cretaceous sequences.

    Keywords: Kharit basin, Landsat-8, rift structure, cretaceous tectonics, multispectral optical dataset
  • Sonu Singh *, Vijay Shankar, Joseph Tripura Pages 1061-1079

    Assessing the groundwater potential (GWP) and protective capacity of aquifers is essential to provide solutions to challenges in aquifer exploration and conditions in hilly terrain regions. The study was conducted in the hilly terrain region of Hamirpur, Himachal Pradesh, India, to obtain one-dimensional vertical electrical sounding (VES) data for groundwater exploration and evaluate the vulnerability of sublayers. Forty VES sites were used in the Schlumberger electrode configuration. The analysis of data resulted in stratified 2-5 different curves. According to the geoelectric sections, there are two to five layers of soil beneath the region i.e. Shale/clay (10-650 Ohm-m), fractured sandstone/gravel/sand (10.3-436 Ohm-m), clay mix gravel/clay mix sand/coarse-grained sandstones (1.06-355 Ohm-m), conglomerate/clay/hard sandstone (60.5-658.7 Ohm-m), sandstone/shale (90.8-125 Ohm-m) with aquifer resistivity (AR) in parenthesis. Aquifer resistivity (AR), longitudinal conductance (S), layer thickness (LT), and transverse resistivity (TR) distribution maps were generated using interpreted VES data for various sub-layers using ArcGIS 10.1. The geologic second and third sub-surface layers are generally porous and permeable. S values for underlying layers are generally less than unity, which indicates vulnerable zones with a significant risk of contamination. Based on the S values, the strata are divided into five categories as Poor (5.55%), weak (19.43%), moderate (19.45%), good (38.89%), and very good (16.68%). Areas with moderate to very good protection capacity are planned as zones with high GWP. The study results are useful in preliminary pollution control and assessment for sustainable groundwater management.

    Keywords: VES, Hydraulic Parameters, Geoelectrical Data, Aquifer protective capacity, Hilly Terrain
  • Debasmita Basu *, Smriti Mishra Pages 1081-1104

    Destination image positioning plays a pivotal protagonist in the accomplishment of mining tourism. By strategically shaping the perception of a mining destination, marketers can entice visitors who are interested in the exceptional experiences and cultural heritage associated with mining. The lack of destination image positioning and mining tourism research can hinder the growth and advancement of mining tourism destinations. Without a clear understanding of the unique attributes and market positioning of a mining destination, it becomes challenging to effectively target and attract the right audience. Insufficient research on mining tourism also limits the ability to identify and capitalize on the destination's potential, such as its cultural heritage, environmental sustainability, or adventure offerings. Without a well-defined destination image and research-backed strategies, marketing efforts may fall short of conveying the value and appeal of mining tourism experiences. Therefore, stakeholders and researchers must invest in studying and understanding the market dynamics, visitor preferences, and the prospective welfares that mining tourism can fetch to local economies and communities. This research can inform effective destination image positioning strategies and help unlock the full potential of mining tourism destinations. Therefore, current environmental, social, and economic viewpoints on the sustainability of this type of tourism growth are outlined in a review of the literature in this area for the Indian scenario.

    Keywords: Mining Tourism, Destination Image, Resident Perception, Economic Impact, environmental impact
  • Kapoor Chand, Radhakanta Koner * Pages 1105-1119

    In open-pit mine, safety of internal dumps is a significant pointer on the economic perspective of the overall project. It has been found in several studies that unplanned and random deposition of the overburdened material is the main reason for mishaps and failure. The study utilized unmanned aerial vehicles (UAVs) to map the mine dumps, and the precise 3D geometry of the same was reconstructed to evaluate the safety using numerical methods. A framework is proposed to assess and identify the potential zone of instability in the mine dumps. The study was conducted at the open-pit mine at the Raniganj coalfield of Paschim Bardhaman in West Bengal, India. The study assessed the internal dump safety using a 3D limit equilibrium method and numerical methods. Finally, optimum parameters are suggested for the mine dumps geometry under the prevailing geo-mining conditions of the mine site. The framework proposed here for assessing critical zones in mine dumps is cost-effective, easy to use, quick, and efficient.

    Keywords: Mine dumps, Slope Stability, Critical zones, Factor of Safety, limit equilibrium method
  • Babatunde Adebayo, Blessing Taiwo *, BUSUYI AFENI, Aderoju Raymond, Joshua Faluyi Pages 1121-1139

    The quarry operators and managers are having a running battle in determining with precision the rate of deterioration of the button of the drill bit as well as its consumption. Therefore, this study is set to find the best-performing model for predicting the drill bit button's wear rate during rock drilling. Also, the rate at which drill bit buttons wear out during rock drilling in Ile-Ife, Osogbo, Osun State, and Ibadan, Oyo State, Southwest, Nigeria was investigated. Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS), and adaptive moment Estimation-based Long Short-Term Memory (LSTM) machine learning approaches were used to create models for estimating the bit wear rate based on circularity factor, rock grain size, equivalent quartz content, uniaxial compressive strength, porosity, and abrasive properties of the rock. The performance of the models was measured using a new error estimation index and four other convectional performance estimators. The analysis of performance shows that the adaptive moment estimation algorithm-based LSTM model did better and more accurately than the other models. Thus, the LSTM models presented can be used to improve drilling operations in real-life situations.

    Keywords: Drilling, Bit wear rate, granite, circularity index, long short-term memory
  • Şener Ceryan, Pijush Samui, Osman Özkan, Samet Berber, Şule Tüdeş, Hakan Elci *, Nurcihan Ceryan Pages 1141-1153

    Balikesir province Akcay district (Biga Peninsula, South Marmara Region, Turkey); the studied area is located on the southern branch of the North Anatolian Fault Zone, where some earthquake, 1867 Edremit (Mw =7.0), 1919 Ayvalik-Sarmisakli (Mw = 7.0), 1944 Edremit (Mw =6.4) and 1953 Yenice (Mw = 7.2) earthquakes occurred in the historical and the instrumental period. In the said area, generally, the groundwater level is high and sandy soils are widespread. In this study, therefore topography, depth of groundwater table and soil characteristics of the said area were investigated in terms of susceptibility to liquefaction. In addition, the safety factor against liquefaction (FL) for the soil layers were determined by using simple procedure based on SPT-N values. Then the spatial distributions of the safety factor at 3 m, 6 m, 9 m, 12 m, 15 m and 18 m depths were obtained. Taking into considering FL values obtained, the liquefaction potential index and the liquefaction severity index of soil profile in the location of boring were calculated, then the spatial distributions of these index were obtained. According to the maps obtained, 5.8% of the studied area has low liquefaction potential, 10.7% medium liquefaction potential, 18.3% high liquefaction potential, and 53.8% very high liquefaction potential, and 22.7% of the study area has very low liquefaction severity, 17.1% low liquefaction severity, 47.7% moderate liquefaction severity, and 1.1% high liquefaction severity and 11.4% of the studied area has none-liquefiable soil.

    Keywords: North Anatolian Fault Zone, Soil liquefaction, liquefaction potential index, liquefaction severity index
  • Tanveer Wagay *, Manju Suthar Pages 1155-1170

    An experiment was conducted to evaluate the load-bearing capacity of a soil nailing system that consisted of four 10mm nails and four 12mm nails, reinforced in a slope with three different flexible facing materials: geo-composite facing, aluminium facing, and galvanized iron facing. The nails were spaced 200mm apart horizontally and vertically from centre to centre. The results of the stress-strain test showed that the geo-composite and galvanized iron facings with 12mm diameter nails exhibited high strength of 0.25N/mm2 with less displacement. The relationship between stress, displacement, and the type of nails used with identical facing was examined. The stability of the slope was also analysed to investigate the impact of nail parameters and type of facing on displacement under varying loading conditions.

    Keywords: Soil nailed slope, Experimental Model, Flexible facing, Displacement, Spacing
  • Sphiwe Emmanuel Mhlongo *, Francis Dacosta, Armstrong Kadyamatimba, George O Akintola Pages 1171-1181

    South Africa has 6100 documented abandoned mines. The government is responsible for the management and rehabilitation of these mines to address their environmental problems, physical hazards, and socio-economic issues. In general, rehabilitating abandoned mines involves making a series of critical decisions about the strategies to be implemented in rehabilitating the major features of these mines. This paper presents an expert system developed to aid in selecting appropriate strategies for rehabilitating abandoned mines in South Africa. This system is known as the Expert System for Selection of Strategies for Rehabilitation of Abandoned Mines (ES-SRSA). The ES-Builder (Version 3.0, McGoo software) was used to design the knowledge and rule-based components of the expert system. The rules of the expert systems were developed based on the documented knowledge of the problems of abandoned mines in South Africa and the information gathered by the researcher through visits to selected abandoned mine sites in the country. The ES-SRSA provides 45 recommendations of suitable strategies for dealing with the different problems of features such as underground entries, mine waste, surface mine excavations, silos and orebins, and other features like dilapidated buildings/infrastructure. Most of the rules of this expert system encourage the repurposing and reuse of these mine features to improve the social and economic status of the host communities. The use of this expert system has the potential of contributing to the reduction of the risks of implementation of ineffective strategies for the rehabilitation of abandoned mines in a country like South Africa.

    Keywords: expert system, Abandoned Mines, rehabilitation strategies, ES-Builder
  • Zehra Khan, Abhishek Sharma * Pages 1183-1203

    Due to rapid growth in infrastructure sector, the construction of high-rise buildings is becoming very popular among all the countries. Engineers face significant issues with high rise buildings, particularly in terms of structural and foundation aspects. Many old design approaches can't be used with certainty since they involve extrapolation far beyond the domains of existing experience, hence structural and geotechnical engineers are being compelled to use more advanced analysis and design methodologies. The current study is an attempt to predict the bearing capacity and settlement behavior of piled-raft footing when embedded into cohesionless deposit. The numerical analysis has been carried out to examine the effect of numerous key parameters of pile and raft such as pile length (10, 15, 20 m), pile diameter (0.3, 0.4, 0.5 m), pile number (16, 20, 24), pile spacing (2D, 3D, 4D) (where “D” is diameter of the pile), raft thickness (0.4, 0.5, 0.6 m), and angle of internal friction of soil (25°, 30°, 35°) on load-settlement behavior of the piled- raft foundation using ABAQUS software. A constant spacing between the piles, i.e. 3D was used throughout the analysis. The results of numerical investigation revealed an improvement in bearing capacity and a reduction in settlement value on increasing length, diameter and number of piles and also with increasing angle of internal friction. The current study not only increases the bearing capacity of the foundation but provides a cost-effective foundation technique to engineers.

    Keywords: Piled-raft foundation, Settlement, Numerical Analysis, Load Carrying Capacity
  • Satya Srikant *, Raghupatruni Rao Pages 1205-1218

    The present paper deals with the development of process flowsheet for recovery of high-grade graphite from rougher graphite concentrate for use in industrial applications. In the present investigation, since the coarser graphite flakes have a higher demand, an attempt is made at every stage of comminution, and flash flotation experiments have been carried out, and the end product obtained by stage comminution followed by flotation has been further subjected to alkali pressure leaching followed by grinding and flotation to recover industrial grade graphite concentrate. During this stage grinding, an additive, a depressant that is being used for depression of silica during flotation, has been used as grinding aid. The data indicates that at any given time of grind, the effect of grinding aid is significantly better as far as the separation efficiency of graphite. Hence, it is concluded that excessive size reduction of graphite is minimised while using a grinding aid. Based on these observations, further studies have been planned for flash flotation using a comminution circuit with grinding aids. The results of the present study reveals that number of cleaning of rougher concentrate alone will not fetch more than 75% of fixed carbon (FC) with less than 8% yield and 41% recovery. The effect of four stage cleanings continued with starvation dosage in grinding circuit followed by flash flotation indicate that the end product achieved contains 97.8% FC with 11.6% yield and 78% recovery and the overall values loss in tailings contain 3.6% FC. The end product achieved by alkali digestion method from a flotation product [97.8% FC] contains 99.2% FC with overall 10.4% yield and 71% recovery. The process adopted in the present investigation is friendly environment and process flowsheet is an innovative. The end product obtained from this process is useful for various industrial applications.

    Keywords: Graphite, Rougher Concentrate, Alkali Digestion, Flash Flotation, Pressure Leaching
  • Chol Ung Ryom, Kwang Hyok Pak, Il Chol Sin, Kwang Chol So, Un Chol Han * Pages 1219-1237

    Scheelite ore with heavy and magnetic minerals can be generally concentrated using shaking table centered gravity-magnetic processing. When magnetic field is formed by fixing magnetic bars on which permanent magnets are arranged at a constant interval, above the table desk, heavy scheelite particles can be concentrated by gravity, whereas heavy magnetic mineral particles can be floated off like light mineral particles by upward magnetic force. In this paper, concentration of scheelite and removal of pyrrhotite floated by magnetic force was simulated using CFD for the sample containing 1% scheelite and 2% pyrrhotite, and compared with the experiment. As a result, WO3 grade and separation efficiency of concentrate were 65.3% and 80.1%, respectively, in the new table equipped with magnetic bars, whereas 28.4% and 76.5%, respectively, in conventional table. The magnetic field formed by fixing magnetic bars above table could be significant in simplifying the sequential tabling-magnetic separation process and reducing the loss of scheelite.

    Keywords: table concentration, scheelite, pyrrhotite, magnetic bar, CFD Simulation
  • Abdallah Atef *, Ahmed Madani, Adel Surour, Mokhles Azer Pages 1239-1260

    This study reports the application of remote sensing data and knowledge-driven GIS modeling to provide favorability maps for gold and copper mineralized areas. The South Gabal Um Monqul (SGUM) and the Gabal Al Kharaza (GKZ) prospects located in the northern Eastern Desert of Egypt are the targets for the present study. Four thematic layers (lithology maps, old trenches buffer analysis, lineament density maps, and alteration zone maps) were prepared and used as inputs for a weighted overlay GIS model. Combined results from false color composite images, particularly the RGB parameters (PC2, PC1, and PC3) and the RGB parameters (MNF1, MNF2, and MNF3) classified the host rocks in both prospects. PCA-based extraction of lineaments was considered using line algorithm of PCI Geomatica. QuickBird band math (G+B), (R+G), and (G-B) for RGB was successful in delineating ancient workings within the mineralized zones. Old trenches layers were buffered to 20 m wide bands extending in all directions. Landsat-8 band ratios imagery (6/5 * 4/5, 6/7, and 6/2) in red, green, and blue (RGB) is potent in defining alteration zones that host gold and copper mineralizations. Acceptable scores of 30%, 30%, 20%, and 20% were assigned for the alteration zone maps, ancient workings buffer analysis, lithology maps and lineament density maps, respectively. Two favorability maps for mineralizations were generated for the SGUM and GKZ prospects. Validation of these maps and their potential application to detect new mineralization sites in the northern Eastern Desert were discussed.

    Keywords: remote sensing, GIS analysis, gold, copper mineralization, Favorability maps, knowledge-driven method
  • Akbar Esmaeilzadeh *, Korosh Shahriar, Reza Mikaeil Pages 1261-1272

    The hydraulic properties of the rock masses are of great importance in analyzing the behavior and stability of the structures constructed on or in rock mass. Permeability is key parameter among other rock mass features due to its important role in rock mass overall behavior. According to aforementioned reason, numerous efforts have been made by researchers in the field of rock mechanics for its obtaining. To access the rock masses’ permeability, in-situ test methods and simulation techniques could be used. In-situ tests like Lugeon Test are time-consuming and costly and they provide local results. Simulation base methods calculate the permeability of the model that is generated similar to the real region indeed and the developing the results to the real condition always raises substantial challenges. according to the aforementioned reason, direct acquiring of permeability with optimum cost and time which is easily generalizable to the overall of a region would be very important. In this work using crack tensor concept, permeability tensor of Lorestan’s Rudbar dam cavern is calculated efficiently by considering rock mass structural features. Resulted permeability of the power plant’s cavern was obtained equal to  that seems to be acceptable compared to the measured values which is obtained  9/87×10-7 m/s.

    Keywords: Crack Tensor, Permeability Tensor, Pumped Storage, Power plant, Rudbar Lorestan
  • Alireza Dolatshahi, Hamed Molladavoodi * Pages 1273-1293

    The structure's response to the region's prevailing loading conditions guides the engineers in estimating the resilience of the structural materials and their reinforcement. One of the main concerns in designing rock structures is paying attention to the size effect phenomenon. The size effect influences the nominal strength, brittleness, load capacity, stress intensity factor, the characteristics of the fracture process zone at the crack tip, and the way and path of crack propagation. Therefore, studying the size effect law will make a guideline for correct decision-making, design, and implementation of efficient support systems. As a comprehensive review, this work investigates specimen size effect on the rock's mechanical and fracture properties. With a comprehensive look at this issue, it explains the essential points that help the engineers design rock structures. During the investigations carried out in this work, it is shown that the specimen size affects the fracture and mechanical properties of the rock. The severity of this phenomenon depends on various factors such as the brittleness index, the shape of the notch or crack length, and the size of the particles that create the rock. In concrete, it depends on the additive boosting materials in the concrete.

    Keywords: Size effect, Mechanical Properties, Fracture process zone, Fracture toughness
  • Nooshin Navi, Mohammad Karamoozian *, Mohammad Khani Pages 1295-1305

    Red mud is an important solid tailing with strong alkalinity that is obtained during the extraction of alumina in the Bayer process. The global reserve of red mud is more than 4 billion tons, and its disposal as tailing has always been a serious environmental problem. This tailing is considered as a potential source, due to its high content of valuable metal compounds including iron. In this research work, the extraction of iron in red mud is investigated by the method of reduction roasting. The main influencing factors are also investigated. These methods include reduction in muffle and tube furnace, and temperature, reduction agent, and additive type are as important factors. Reduction roasting of the samples in a tube furnace, with Argon gas and vacuum, a mixture of red mud, graphite, and sodium carbonate at 700–1000 °C results in the formation of Fe3O4. Magnetic measurements indicate that saturation magnetization increases from 0.239 to 38.205 emu/g due to the formation of Fe3O4. Applying the magnetic field intensity of about 1000 Gauss results in the iron recovery of 89.9%.

    Keywords: Red Mud, Reduction-Roasting, Muffle furnace, Tube furnace, Vibrating Sample Magnetometer
  • Pedram Ashtari *, Saeid Karimi, Seyyede Atefeh Hosseini Pages 1307-1319

    In this research work, the reductive leaching of pyrolusite in a sulfuric acid medium with the aid of orange peel as a reductant was investigated. The important parameters affecting the leaching process include temperature in the range of 25 to 95 °C, the weight ratio of reducing agent to pyrolusite (R/P) in the range of 0 to 2 (w/w), and the concentration of sulfuric acid in the range of 0.05 to 0.25 M. According to the results, the parameters of temperature and the R/P are more significant in the reductive leaching process. With increasing temperature from 25 to 95 °C, Mn recovery increases from 0.5% to 52.5%. Also Mn recovery with a two-step increase in 0-0.1 and 0.1-1.5 of the R/P indicates a jump of 28.5% and 19.0%, respectively. Sulfuric acid concentration shows its effect by supplying sulfate and hydrogen ions in the leaching process. The successful use of orange peel as a reductant was confirmed by achieving a manganese dissolution efficiency of 98.1% under optimum conditions (temperature of 90 °C, sulfuric acid concentration of 0.1 M, and R/P ratio of 1.5 (w/w)). Kinetic investigations showed that the shrinking core model could not be used to determine the leaching mechanism of pyrolusite in the presence of fruit peel reductant. Avrami's kinetic model with very high fitting accuracy was used to determine the kinetic model of pyrolusite leaching.

    Keywords: Pyrolusite, Manganese reductive leaching, Orange peel, Kinetic evalution, Avrami model
  • Mohammadjafar Mohammadzadeh *, Majid Mahboubiaghdam, Moharram Jahangiri, Aynur Nasseri Pages 1321-1342

    Most machine learning-monitored algorithms used to create mineral potential prediction maps require noise-free data to achieve high performance and reliable results. Unsupervised clustering methods are highly effective for uncovering a dataset’s hidden structures. Therefore, this study attempts a combination of supervised and unsupervised methods employing training and testing data to generate a highly accurate potential map of the Sonajil copper-gold deposit located in the NW of Iran. Here, a semi-supervised Bayesian algorithm is used to map the mineral landscape. Initially, ten raster layers of exploratory features are prepared. Then based on the copper concentration, 27 exploratory drilled boreholes are divided into four classes, C1 to C4, and from each class, two boreholes are selected, and 100-meter buffering is performed around these boreholes to extract 1113 training data based on the behavioral pattern of boreholes and surface samples. Subsequently, the existing data is clustered using the FCM method, and the total dataset and the clustering data are entered into the Bayesian algorithm to evaluate the accuracy of the Bayesian classifier method across five distinct clusters. The results show increased average accuracy when using clustered data instead of whole data for MPM mapping. Notably, the Bayesian semi-supervised algorithm achieved an impressive accuracy rate of 96% when cluster five data is excluded. To validate the Bayesian semi-supervised method, boreholes data that is not used in training were employed, which confirm the credibility of generated MPM. Overall results highlight the value of the Bayesian semi-supervised algorithm in improving the accuracy and reliability of mineral prospectivity mapping via the application of the FCM clustering method that efficiently organize the data, enabling the Bayesian algorithm to evaluate the accuracy of the Bayesian classifier method across different clusters and providing a successful optimal result in detecting blind ores in areas without exploratory boreholes and delineating more mineralization targets in the Sonajil and adjoining areas.

    Keywords: Cu-Au mineral prospectivity map, Bayesian semi-supervised method, Sonajil, E-Azerbaijan
  • Erfan Amini, Masoud Mojarab, Hossein Memarian * Pages 1343-1359

    Landslides are defined as the downward movement of a portion of land materials under the direct influence of gravity. Landslides would get triggered by a wide spectrum of initiative factors such as earthquakes as a site effect of that event. In the vicinity of Tehran, significant historical earthquakes have occurred; therefore, tracing them could enhance the Tehran’s historical earthquake catalogue, due to the reason Tehran is a metropolitan and capital of Iran. However, paleoseismology could not determine the magnitude and seismic characteristics of historical earthquakes. Mobarak Abad landslide is a large and historical landslide located on Haraz road, a vital artery connecting Tehran to the Mazandaran Province, and there are significant faults like Mosha, North Alborz, and Khazar in its neighborhood. Hence, it is probable that this landslide occurred due to the generation of dynamic force resulting from an earthquake. Therefore, in this study, the geometrical characteristics of the landslide were measured by field surveying. Then with the empirical equations proposed by various researchers, we estimated the landslide volume and the magnitude of the corresponding earthquake, respectively. In the following, the epicenter and hypocenter of all the historical earthquakes within 200 kilometers of the landslide were identified. Then we utilized some conditions such as Keefer's graphs, error value in epicenter location, and peak ground acceleration to omit earthquakes and identify the corresponding earthquake event. The results demonstrate that two earthquakes of 1830 AD and 855 AD with a maximum acceleration of 0.16g are more probable than the 743 AD earthquake.

    Keywords: Empirical Equations, landslide volume, magnitude, epicenter, hypocenter, Peak ground acceleration
  • Vahab Sarfarazi, Hadi Haeri *, Mohammad Fatehi Marji, Gholamreza Saeedi, Amir Namdarmanesh Pages 1361-1371

    In this paper, the effect of variations in the number and area of the rock bridges on the non-persistent discontinuities is investigated. In this regard, blocks containing rock bridges and joints with dimensions of 15 cm * 15 cm * 15 cm are prepared from plaster. The available rock bridges that have occupied 0.2, 0.4, and 0.6  of the shear surface show latitudinal extension along the shear surface. There are variations in the number and extension of the rock bridges in the fixed area. For each of the samples, tests are performed on three blocks of the same material, by putting it under various direct normal stresses. Normal stresses were 3.33, 5.55, 7.77 kg/cm2. Also the obtained shear strength by laboratory tests was compared with the outputs of Jenning's criterion and Guo and Qi's criterion to determine the accuracy of these criteria for predicting the shear strength of non-persistent joints. The results show that the tensile crack started in the rock bridge under normal stress of 3.33 kg/cm2. Mixed-mode tensile shear cracks were propagated in the rock bridge under a normal stress of 5.55 kg/cm2, while a pure shear crack developed in the rock bridge under a normal stress of 7.77 kg/cm2. With the increase of normal stress, the number of microfractures increased. The variance in the number of rock bridges in the fixed area of the rock bridge does not affect the friction angle along the shear surface. Furthermore, the cohesion along the shear surface shows a small decrease with the increasing number of rock bridges. Also by the increase in the area of rock bridges, the friction angle along the shear surface remains constant, while at the same time, there is an almost linear increase in cohesion. Guo and Qi's criterion predicts the shear strength of the non-persistent joint exactly close to the shear strength of the physical samples.

    Keywords: rock bridge, shear failure, Shear Properties
  • Sajjad Rezaei *, Ramin Rafiee, Mohammad Ataei, Morteza Javadi Pages 1373-1391

    The stability of waste dumps is a significant and at times critical issue in the development of surface mines. Due to insufficient space for waste disposal, environmental concerns, and various other factors, Mine No. 4 at Golgohar Sirjan is not capable of establishing a new waste dump. Given the existing limitations of the mine, the investigation has focused on increasing the dump capacity through the implementation of benches. In this research work, the stability of the waste dump has been investigated using the limit equilibrium method with the Slide3D software, along with a Monte Carlo simulation approach for probabilistic analysis. The results obtained from these methods have been compared with each other. The acceptable safety factor considered for this assessment ranges from 1.15 to 1.2. By adding benches to the eastern waste dump of the mine, a displaced volume equivalent to 36,715.565 cubic meters has been added to the capacity. The constructed model is based on the topography of the area, with dimensions of 1850 meters in length, 1750 meters in width, and 160 meters in height. The results indicate that the safety factor of the waste dump has been calculated as follows using the Spencer, Janbu, and Bishop methods respectively: 1.26, 1.199, and 1.226. Mine No. 4 needs to extract 983.58 million tons of waste to produce 73 million tons of iron ore. In total, by discharging 428 million tons of waste in the northeastern and eastern dumps and adding a bench, a volume of 555.571 million tons of waste is available for disposing of the remaining waste. Considering the remaining waste volume, space must be allocated for waste disposal to Mine No. 4.

    Keywords: Waste dump stability, limit equilibrium method, Slide3D software, Monte Carlo simulation method, Golgohar Sirjan mine