فهرست مطالب

Mining and Environement - Volume:13 Issue: 1, Winter 2022
  • Volume:13 Issue: 1, Winter 2022
  • تاریخ انتشار: 1401/02/07
  • تعداد عناوین: 20
  • E. Koken *, E. Başpınar Tuncay Pages 1-13

    Andesites with a satisfactory quality have been mainly considered as dimension stones worldwide. However, practical approaches are required to evaluate the dimension stone quality due to the increasing demand for natural resources. This study presents detailed laboratory investigations on andesitic rocks in NE Uşak, Turkey. For laboratory studies, representative rock blocks are obtained from unweathered (W0) to highly weathered (W3) rock masses. Laboratory test results demonstrate that progressive rock weathering has remarkable influences on the dry density (ρd), effective porosity (ne), pulse wave velocity (Vp), uniaxial compressive strength (UCS), flexural strength (FS), and Böhme abrasion value (AWR) of the andesitic rocks. Of the above parameters, ne seems to be the most affected rock property due to progressive rock weathering. Furthermore, based on the three-parameter Weibull distribution, andesitic rocks are evaluated for their use as cladding stones. A quantitative approach called the suitability index (SI) is proposed to quantify the quality of cladding stones for andesitic rocks, considering six different evaluation criteria (C1–C6). Two examples of SI calculations reveal the implementation of the proposed approach. The suitability of the proposed approach is also checked by Monte Carlo analysis, showing that the use of SI is suitable to quantify the cladding stone quality for the investigated andesitic rocks. However, the proposed approach should be improved by incorporating the mineralogical and textural characteristics into the SI calculations. Moreover, it should also be attempted to different andesitic rocks in order to observe the similarities or difficulties of quantifying the quality of cladding stones.

    Keywords: Andesite, Cladding Stone, Rock weathering, Weibull distribution
  • M. Diab, M. Abu El Ghar, I. Mohamed Gaafar, A. H. Mohamed El Shafey, A. Wageh Hussein, M. Fawzy * Pages 15-32

    In this work we are concerned with the potentiality of using mineral processing for raising the grade of the valuable heavy minerals (VHMs) from the Quaternary stream sediments of Wadi and Delta Sermatai located on the southern coast of the Red Sea, Egypt. A rigorous understanding of the chemical and mineralogical characteristics of the studied samples is a prerequisite for the selection and development of the physical processing used in order to produce a high-grade concentrate. For this purpose, the grain size distribution analysis, heavy liquid separation tests as well as XRF, and SEM analysis are performed.  The magnetite, ilmenite, garnet, zircon, rutile, apatite, sphene, pyrolusite, celestine, and heavy green silicates are the valuable heavy minerals recorded in the studied samples; but their quantity varies between Wadi and Delta. The upgrading experiments are performed via a shaking table in conjunction with the low and high-intensity magnetic separator in order to obtain the high-grade concentrates from the valuable heavy minerals, and after applying the optimum separation conditions, the total heavy mineral (THM) assay increase from 8.32% to 46.04% for Wadi Sermatai, while for Delta Sermatai increase from 8.37% to 50.13% into 8.89% and 9.59%, respectively, by mass yield. The THM recovery values reach 66.84% for Wadi Sermatai and 67.23% for Delta Sermatai. After the results of the chemical analysis of the concentrates, it is proved that the Sermatai area is considered as a potential source for some economic elements such as Fe, Ti, Zn, Zr, Cr, V, and Sr.

    Keywords: Sermatai, southern coast of the Red Sea, Valuable heavy minerals, Gravity Concentration, Magnetic Separation
  • K. Dachri *, Kh. Naji, K. Nouar, I. Benzakour, Kh. Ouzaouit, M. Badri, A. Boussetta, H. Faqir, Kh. El Amari, M. Hibti Pages 33-51

    This work aims to define an efficient and innovative tool in order to make early metallurgical predictions of the Tizert deposit in western Anti-Atlas-Morocco. To do this, the mineralogical approach is used as a tool of gometallurgical prediction using a combination of the lithological field observations on representative drill cores, microscopic characterization performed on 54 thin sections, and automated quantitative mineralogy (AQM) conducted on five composite samples. The metallurgical prediction of the Tizert ore is based on the liberation data, notably on the copper content locked in the gangue and on unrecoverable copper buried as a solid matrix in the gangue minerals (refractory copper). In order to ensure the validity of the proposed method, the results of mineralogical prediction are compared with the flotation test work performance. As a result, the predicted copper recovery results from the mineralogical data are practically the same as those obtained through the flotation tests, showing a maximum difference of 2.02%, an R2 value of 0.96, and a Root Mean Square Error of 1.64%. These results indicate that using the AQM data, the copper recovery could be predicted accurately for the Tizert ore. Furthermore, an early prediction of the flotation performance is very useful in the geo-metallurgical model conception. In addition, such an approach ensures visibility throughout the life of the mine, and provides quick and cost-effective data for processing the performance. On an industrial scale, the applicability of this method can be expanded further by integrating the mineralogical approach into all steady-state processes in order to cover the possible mineralogical variety during the operations, and ensure an industrial process control.

    Keywords: Automated quantitative mineralogy, Tizert, Copper, geometallurgy, Morocco
  • S. Shaffiee Haghshenas *, R. Mikaeil, A. Esmaeilzadeh, N. Careddu, M. Ataei Pages 53-67

    Predicting the amperage consumption of cutting machines could be one of the critical steps in optimizing the energy-consuming points for the dimension stone cutting industry. Hence, the study of the relationship between the operational characteristics of cutting machines and rocks with focusing on the machine's energy-consuming is unavoidable. For this purpose, in the first step, laboratory studies under different operating conditions at different cutting depths and feed rates are performed on 12 soft and hard rock samples. In the continuation of the laboratory studies, the rock samples are transferred to the rock mechanics laboratory in order to determine the mechanical properties (uniaxial compressive strength and modulus of elasticity). The statistical studies are performed in the SPSS software in order to predict the electrical current consumption of the cutting machine according to the mechanical characteristics of the rock samples, cutting depth, and feed rate. The statistical models proposed in this work can be used with a high reliability in order to estimate the electrical current consumed in the cutting process.

    Keywords: Stone cutting process, Hard rocks, Soft rocks, Electrical current consumption, Statistical Studies
  • S. Alamdari, M.H. Basiri *, A. Mousavi, A. Soofastaei Pages 69-85

    The haul trucks consume a significant energy source in open-pit mines, where diesel fuel is widely used as the main energy source. Improving the haul truck fuel consumption can considerably decrease the operating cost of mining, and more importantly, reduce the pollutants and greenhouse gas emissions. This work aims to model and evaluate the diesel fuel consumption of the mining haul trucks. The machine learning techniques including multiple linear regression, random forest, artificial neural network, support vector machine, and kernel nearest neighbor are implemented and investigated in order to predict the haul truck fuel consumption based on the independent variables such as the payload, total resistance, and actual speed. The prediction models are built on the actual dataset collected from an Iron ore open-pit mine located in the Yazd province, Iran. In order to evaluate the goodness of the predicted models, the coefficient of determination, mean square error, and mean absolute error are investigated. The results obtained demonstrate that the artificial neural network has the highest accuracy compared to the other models (coefficient of determination = 0.903, mean square error = 489.173, and mean absolute error = 13.440). In contrast, the multiple linear regression exhibits the worst result in all statistical metrics. Finally, a sensitivity analysis is used to evaluate the significance of the independent variables.

    Keywords: Fuel consumption, Haul truck, Machine learning, Prediction, Open-Pit Mine
  • M. Bahaaddini *, M. Serati, M. H. Khosravi, B. Hebblewhite Pages 87-100

    A proper understanding of the shear behaviour of rock joints and discontinuities is yet a remaining challenge in the rock engineering research works owing to the difficulties in quantitatively describing the joint surface roughness both at the field and the laboratory scales. Several instruments and techniques have been developed over the years for the surface characterisation of joints at the field- and laboratory-scale investigations, amongst which the application of the photogrammetry methods has obtained a growing popularity. This work evaluates the applicability of the photogrammetry techniques for the characterisation of joint surface topography and texture at micro-scales, which has been largely understudied in the literature. Three tensile joint surfaces are digitized using photogrammetry, and the results are compared with those obtained from laser scans with a high 3D accuracy. A comprehensive statistical analysis is then undertaken on the digitized point clouds in order to assess the performance of photogrammetry in surface characterisation. The results of this work show that the height differences between the resulting point clouds from the two adopted techniques (photogrammetry and 3D laser scanning) follow the normal distribution with the mean values close to zero. The statistical analyses illustrate that the measured joint surfaces using the photogrammetry techniques are in good agreement with the laser scanning data, confirming that photogrammetry is a capable method for characterising the joint surface roughness even at micro-scales. Interestingly, the results obtained further indicate that the accuracy and preciseness of the photogrammetry techniques are independent from the joint roughness coefficient but the camera and configuration parameters remarkably control the performance of the measurement.

    Keywords: Joint surface roughness, Rock joint, Shear behaviour, Photogrammetry, Laser scanner
  • F. Doulati Ardejani *, S. Maghsoudy, M. Shahhosseini, B. Jodeiri Shokri, Sh. Doulati Ardejani, F. Shafaei, F. Amirkhani Shiraz, A. Rajaee Pages 101-115

    Considering that mining has many environmental impacts from the exploration phase to production and finally closure, it is necessary to plan the activities so that the concept of green mining is realized in its true meaning. This means that mining is carried out in order to obtain the minerals that are used in various industries; however, by taking appropriate measures, the impacts of mining on the environment are reduced to a minimum level. Since there is little information about the environmental, ecological, hydrological, and hydrogeological status in most mining areas, a comprehensive study of the area's water, soil, plants, and animal species should be conducted. The existence of permanent and seasonal rivers in the vicinity of some mines, in some cases being located in protected areas of the Iranian Department of Environment, and the presence of vegetation near some mines are among the matters that cause many environmental challenges in the mining areas. For this purpose, a series of comprehensive studies are critical in the pre-mining, during mining, and closure phases of the mine life. In addition, detailed studies should be done on factories such as smelters located in the mining areas. Life cycle assessment (LCA) is widely used in order to determine the environmental status of these factories. Furthermore, the issue of process water and water recycling, as well as waste management, should be considered. Nowadays, the environmental monitoring technology is one of the widely used tools in many mines in the world. Moreover, these mining companies' green space management system should be given special attention according to the obligatory standards of the Iranian Department of Environment. In this paper, a conceptual framework for the green mining method will be introduced for the coal mines to consider the economic and social aspects, and we pay a special attention to the health, safety, and environmental requirements.

    Keywords: Environmental Impacts, Health effects, Green mining components, LCA, Green management plan
  • V. Sarfarazi *, K. Asgari Pages 117-128

    Particle Flow Code in Two Dimensions (PFC2D) was used in order to examine the influence of single tunnel and twin tunnel on the collapse pattern and maximum ground movement. Since first PFC was calibrated by the experiments, the results obtained were rendered by a uniaxial test. Further, a rectangular model with dimensions of 100 m ˟ 100 m containing both the central tunnel and twin tunnel was built. The center of the single tunnel was placed 25 m under the ground surface, and its diameter changed from 10 m to 35 m with an increment of 5 m. The center of the twin tunnel was situated 25 m under the ground surface, and its diameter was changed from 10 m to 30 m with an increment of 5 m. For measurement of the vertical displacement, one measuring circle with a 2 m diameter was opted on the ground surface above the tunnel roof. The average of the vertical movement of discs covered in these circles was determined as a ground settlement. A confining pressure of 0.01 MPa was applied on the model. The uniaxial compression strength was 0/09 MPa; the results obtained depicted that the tunnel diameter controlled the extension of the collapse zone. Also the vertical displacement at the roof of the tunnel declined by decreasing the tunnel diameter. The ground settlement increased by increasing the tunnel diameter.

    Keywords: Tunnel, PFC2D, Settlement
  • M. Esmailzadeh, A. Imamalipour *, F. Aliyari Pages 129-153

    The main aim of mineral exploration is to discover the ore deposits. The mineral prospectivity mapping (MPM) methods by employing multi-criteria decision-making (MCDM) integrate the exploration layers. This research work combines the geological, alteration, and geochemical data in order to generate MPM in the Kighal-Bourmolk Cu-Mo porphyry deposit. The overlaying of rock units and fault layers was used to prepare the geological layer. The remote sensing and geological studies were employed in order to create an alteration layer. For generating the geo-chemistry layer, the stream sediment and lithogeochemical data were utilized. The lithogeochemistry layer was categorized into 9 ones including Cu, Mo, Bi, Te, the alteration indices (e.g. potassic, phyllic, and propylitic), and the geochemical zonality indices (e.g. Vz1 and Vz2). In addition, the stream sediment layer was categorized into 6 layers including Cu, Mo, Bi, Te, and the geochemical zonality indices (e.g. Vz1 and Vz2). By examination of the created layers, the consistency of the potential areas was verified by field surveys. Afterward, the weights were assigned to each layer considering the conceptual model of porphyry copper systems. Consequently, the layers were integrated by the fuzzy gamma operator technique, and the final MPM was generated. Regarding the generated MPM, 0.86% of the studied area shows a high potential porphyry mineralization, and these areas are proposed for the subsequent exploration drilling locations.

    Keywords: Mineral Prospectivity Mapping (MPM), Cu-Mo-Au Porphyry, Fuzzy Gamma operator, Mineralization, Kighal-Bourmolk
  • M. Mahjoore, A. Aryafar *, M. Honarmand Pages 155-164

    In the present work, the cadmium oxide (CdO) nanoparticles (NPs) are synthesized using the Ferula extract. Ferula acts as a naturally-sourced reducing agent and stabilizer for the construction of the CdO NPs. The biosynthesized CdO NPs are characterized by different techniques such as X-ray powder diffraction (XRD), Fourier transform-infrared (FT-IR), spectroscopy and field emission-scanning electron microscopy (FE-SEM). After ensuring a successful synthesis of the CdO NPs, their photocatalytic activity is studied for the degradation of ciprofloxacin antibiotic in aqueous media under the sunlight. Approximately 95% degradation of ciprofloxacin using the CdO NPs is achieved after 60 minutes. The recycling experiments confirm the high stability and durability of the CdO NPs. Therefore, this work illustrates an efficient strategy for the photo-degradation of ciprofloxacin, and provides a new insight into the removal of pharmaceutical contaminants in aquatic environments.

    Keywords: Cadmium oxide, Nanoparticles, Ferula, Photocatalyst, Ciprofloxacin antibiotic
  • A. Moeini, S. Mohammadnejad * Pages 165-174

    A comprehensive utilization of concentrated seawater is crucial in order to promote the development of the desalination industry as a key solution to global freshwater. Debromination of the desalination plant effluent as well as the bromine product extraction are two parallel goals, which have been the subject of many research studies as well as industrial operations. In this investigation, bromine extraction is investigated experimentally form the effluent of the Konarak desalination plant located in Chabahar bay, Iran. For this purpose, an air blow-out method is used, and the effects of the operating parameters including the temperature, pH, and chlorine gas flow rate are examined in a continuous reactor. The parameters are optimized, and the trend is discussed in details. The bromine concentration of the sample collected from the Pozm Tiyab area, close to the plant discharge point, has been determined to be 1.172 g/L using ion chromatography. A pre-concentration procedure is conducted in order to reach a concentration of 3.100 g/L by evaporation. A reactor with the dimensions of 60 mm × 800 mm is designed and assembled for the experimental studies. In order to investigate the operating parameters, a central composition design (CCD) method is used. Among the factors studied, only the chlorine gas flow rate has a substantial effect on the bromine recovery, and the effects of the other two factors are negligible in the pH range of 2-3 and the temperature range of 50-70 °C. At the three chlorine concentrations of 1, 1.5, and 2 L/min, the bromine production increases almost linearly with the increasing chlorination injection rate. The Br2 gas is recovered with a maximum rate of 93.8% and a bromine loss of 185 mg/L in the mother liquid. The optimum operating parameters to achieve this recovery are a pH of 2.5, a temperature of 60 ˚C, and a chlorine gas flow rate of 1.5 L/min.

    Keywords: bromine, air blow-out, desalination plant discharge
  • M. Ghaedi Ghalini, M. Bahaaddini *, M. Amiri Hossaini Pages 175-184

    Estimation of the in-situ block size is known as a key parameter in the characterization of the mechanical properties of rock masses. As the in-situ block size cannot be measured directly, several simplified methods have been developed, where the intrinsic variability of the geometrical features of discontinuities are commonly neglected. This work aims to estimate the in-situ block size distribution (IBSD) using the combined photogrammetry and discrete fracture network (DFN) approaches. To this end, four blasting benches in the Golgohar iron mine No. 1, Sirjan, Iran, are considered as the case studies of this research work. The slope faces are surveyed using the photogrammetry method. Then 3D images are prepared from the generated digital terrain models, and the geometrical characteristics of discontinuities are surveyed. The measured geometrical parameters are statistically analysed, and the joint intensity, the statistical distribution of the orientation, and the fracture trace length are determined. The DFN models are generated, and IBSD for each slope face is determined using the multi-dimensional spacing method. In order to evaluate the validity of the generated DFN models, the geological strength index (GSI) as well as the stereographic distribution of discontinuities in the DFN models are compared against the field measurements. A good agreement has been found between the results of the DFN models and the filed measurements. The results of this work show that the combined photogrammetry and DFN techniques provide a robust, safe, and time-efficient methodology for the estimation of IBSD.

    Keywords: Jointed rock mass, In-situ block size, Photogrammetry, Discrete Fracture Network, Golgohar iron mine
  • M. Hosseini *, A.R. Dolatshahi, E. Ramezani Pages 185-200

    Concrete is among the widely used materials in all industries and mineral and civil activities worldwide, highlighting its significance. Most natural and non-natural phenomena can influence the concrete's physical and mechanical properties, causing many irreparable damages. Acid rain is a natural inevitable phenomenon, particularly in industrial zones with high pollution percentages.This work investigates the effect of acid rain on the concrete specimens containing micro-silica and limestone powder. To this end, the concrete specimens are divided into six groups. Throughout this paper, CN represents the concrete without micro-silica and limestone powder under no-rain conditions, CO is the concrete without micro-silica and limestone powder under normal rain conditions, CA  is the concrete without micro-silica and limestone powder under acid rain conditions, CMLN is the concrete containing micro-silica and limestone powder under no-rain conditions, CMLO is the concrete containing micro-silica and limestone powder under normal rain conditions, and CMLA shows the concrete containing micro-silica and limestone powder under acid rain conditions. The measured physical properties are the effective porosity, dry density, water absorption, and velocity of longitudinal waves. The mechanical properties including the Brazilian tensile strength, uniaxial compressive strength, triaxial compressive strength, cohesion, and internal friction angle are also measured. For the samples of CN and CMLN, they are tested under no rainfall conditions, whereas the samples of CA and CMLA are tested after 20 cycles of acid rain (pH = 2). The samples of CO and CMLO are also tested after undergoing 20 normal rain cycles (urban water with pH = 7). In each test cycle, there is 1 hour of rain and 1 hour of no rain. The results obtained show that adding micro-silica and limestone powder improves its properties so that the decrease in the effective porosity, longitudinal wave velocity, dry unit weight, water absorption, Brazilian tensile strength, uniaxial compressive strength, cohesion, and internal friction angle of the specimens of CMLA is less than those for the specimens of CA.

    Keywords: Acid rain, Concrete, Microsilica, Limestone powder, Physical, Mechanical Properties
  • H. Fattahi *, F. Jiryaee Pages 201-216

    The surface settlement is an essential parameter in the operation of mechanized tunneling that should be determined before excavation. The surface settlement analysis caused by mechanized tunneling is a geo-technical problem characterized by various sources of uncertainty. Unlike the deterministic methods, the reliability analysis can take into account the uncertainties for the surface settlement assessment. In this work, the reliability analysis methods (second-order reliability method (SORM), Monte Carlo simulation (MCS), and first-order reliability method (FORM)) based on the genetic algorithm (GA) are utilized to build models for the reliability analysis of the surface settlement. Specifically, for large-scale projects, the limit state function (LSF) is non-linear and hard to apply based on the reliability methods. In order to resolve this problem, the GMDH (group method of data handling) neural network can estimate LSF without the need for additional assumptions about the function form. In this work, the GMDH neural network is adapted to obtain LSF. In the GMDH neural network, the tail void grouting pressure, groundwater level from tunnel invert, depth, average penetrate rate, distance from shaft, pitching angle, average face pressure, and percent tail void grout filling are used as the input parameters. At the same time, the surface settlement is the output parameter. The field data from the Bangkok subway is used in order to illustrate the capabilities of the proposed reliability methods.

    Keywords: Surface settlement, Mechanized tunneling, Reliability methods, GMDH neural network, Genetic Algorithm
  • B. Alipenhani, A. Majdi *, H. Bakhshandeh Amnieh Pages 217-233

    Determining the hydraulic radius of the undercut in the block caving method is one of the key issues in this method. The hydraulic radius is directly related to the minimum caving span. In this research work, the rock mass cavability is investigated using the UDEC and 3DEC software. Since the factors affecting the cavability are very diverse and numerous, firstly, by 2D modeling in the UDEC software and examining the trend of changes in the minimum caving span, the most important factors including the depth, dip of the joint, number of joints, angle of friction of the joint surface, and joints spacing are selected for the final study. The variation trend of each variable is investigated by keeping the other variables constant (single-factor study) among various factors. In the second step, the minimum caving span for the five main factors and values is ​​determined in the single-factor study using the SPSS software and the multivariate regression method. Then the power function of the minimum caving span is chosen based on the selected variables with a coefficient of determination of 0.76. In continuation, a simple 3D model is built from the undercut. A linear equation is achieved between the results of the 3D and 2D modeling results in similar conditions. In a model with certain conditions, using the equation obtained from the numerical method, the calculated hydraulic radius of caving is 22.5 m, which is close to the result obtained from the Laubscher's empirical method with the same condition (24 m).

    Keywords: Cavability, minimum caving span, Numerical method, Multivariate Regression
  • M. Hosseini, H. Madani *, K. Shahriar Pages 235-251

    The main purpose of this work is modeling the dispersion of the sarin gas in a subway station in a hypothetical scenario. The dispersion is modeled using the CFD approach. In the analysis of the environmental conditions of the underground spaces, the only factor that draws a distinction between a subway station and other spaces is the train piston effect. Therefore, the present research work models the sarin dispersion in the two general cases of with and without a train in the subway system. About 0.5 L of sarin is assumed to be released through the main air handling unit (AHU) of the station. The results obtained show that in the case with no train service in the station, after 20 minutes of sarin release, the concentration and dose of sarin in the station will be 8.9 mg/m3 and 80 mg minute/m3, respectively, and these values are highly dangerous and lethal, and would have severely adverse effects on many individuals, and lead to death. This is highly important, especially when the effect of ventilation chambers at the ground level is taken into consideration. The results obtained also show that the train piston effect reduces the concentration and dose of sarin in the station so that when train arrival at and departure from the station, the sarin dose considerably reduces to 25 mg min/m3 after the release, and contributes to lower casualties. Finally, the results obtained show that time is a key factor to save lives in the management of such incidents.

    Keywords: Sarin, Chemical attack, CFD, Subway Station, Piston effect
  • H. Shahriari *, M. Honarmand, S. Mirzaei, A. Saffari Pages 253-267

    This research work aims to discuss the methodology of using the drone-based data in the initial steps of the exploration program for the dimension stone deposits. A high-resolution imaging is performed by a low-cost commercial drone at the Emperador marble quarry, Kerman province, Iran. A ground resolution of 3 cm/pix is achieved by imaging at an altitude of 70 m in order to ensure the precise lithological and structural mapping. An accuracy of less than 5 cm is promised for the 3D photogrammetric products. Hence, the flight is performed with an 80% front and a 70% lateral image overlap. Furthermore, 18 ground control points (GCPs) are used in order to meet the required accuracy. Photogrammetric processing is done by the Agisoft PhotoScan software. The geology map is prepared through the visual geo-interpretation of the orthophoto image. The faults and fractures are delineated using the high-resolution orthophoto and hill-shade model in the ArcGIS software. Accordingly, the density map of fractures is produced, and the deposit is divided into five structural zones. The 3D deposit model with an accuracy of 2.8 cm is reconstructed based on the digital elevation model (DEM). A primary block model is generated using the 3D deposit model in the Datamine software in order to determine the resource for each structural zone. Finally, considering the amount of resource and situation of fractures, the priority of exploration for developing activities and appropriate methods is defined for each structural zone. The research work results have convinced us to include drone-based imagery in the initial steps of dimension stone exploration to consume the time and cost of the operation.

    Keywords: drone-based imagery, Photogrammetry, 3D deposit model, block model, reserve estimation
  • Numerical Modelling of Slide-Head-Toppling Failure using FEM and DEM Methods
    H. Sarfaraz *, A.R. Bahrami, R. Samani Pages 269-280

    A common instability in the rock slopes is a toppling failure. If this type of slope failure occurs due to another kind of failure, it is considered as the secondary toppling failure. A type of secondary toppling failure is the slide-head-toppling failure. In this instability, the upper portion of the slope is toppled, and the pressure caused by the overturning of rock blocks leads to a semi-circular sliding in the soil mass at the slope toe. This instability is examined through the theoretical analysis and physical modelling. Firstly, the failure mechanism mentioned above is described. Next, the slide-head-toppling failure is studied through seven numerical simulations. The Phase2 and UDEC softwares, as the finite element and distinct element methods, respectively, are used in this work. Different kinds of slide-head-toppling failure are modelled such as the blocky, block-flexural, and flexural toppling failures. The numerical modelling results are compared with the existing physical tests and theoretical approaches. This comparison illustrates that the safety factor is underestimated due to the plane strain supposition in numerical modelling. However, the side-friction in the physical models has violated this assumption. The results obtained demonstrate that the distinct element method has an acceptable accuracy compared to the finite element method. Thus this numerical code can be used in order to examine the mentioned failure.

    Keywords: Rock Slopes, Slide-Head-Toppling, Numerical Simulation, DEM, FEM Methods
  • J. Zadhesh, A. Majdi * Pages 281-308

    The mechanisms of deformation and failure of the structures in and on the jointed rock masses are often governed by the characteristics of the geometrical properties of joints. Since the joint geometry properties have a range of values, it is helpful to understand the distribution of these values in order to predict how the extreme values may be compared with the values obtained from a small sample. This work studies three datasets of joint systems (1652 joint data) from nine outcrops of igneous, sedimentary, and metamorphic rocks in order to determine the probability distribution function of the rock joint geometry properties. Consequently, the goodness-of-fit (GOF) tests are applied to obtain the data. According to these GOF tests, the Lognormal is the best probability distribution function representing the joint spacing, aperture, and trace length. The Cauchy is the best probability distribution function for the joint dip angle. It is found that the Cauchy distribution function is the best probability distribution function to represent the joint dip direction of igneous rocks, and the Burr distribution function is the best probability distribution function to define the joint dip direction of the sedimentary and metamorphic rocks.

    Keywords: Rock Joint Geometry Properties, Spacing, Aperture, Trace Length, Goodness-Of-Fit Tests (GOF)
  • F. Mirsepahvand, M.R. Jafari, P. Afzal *, M. A. Arian Pages 309-324

    The goal of this research work is to recognize the metallic mineralization potential in the Ahar 1:100,000 sheet (NW Iran) using the remote sensing data based on determination of the alteration zones. This area is located in the Ahar-Arasbaran metallogenic zone as a significant metallogenic zone in Iran and Caucasus. In this research work, the Landsat-7 ETM+ and advanced space borne thermal emission and reflection radiometer (ASTER) multispectral remote sensing data was interpreted by the least square fit (LS-Fit), spectral angle mapper (SAM), and matched filtering (MF) algorithms in order to detect the alteration zones associated with the metallic mineralization. The results obtained by these methods show that there are index-altered minerals for the argillic, silicification, advanced argillic, propylitic, and phyllic alteration zones. The main altered areas are situated in the SE, NE, and central parts of this region.

    Keywords: Least square fit, Spectral angle mapper, Matched filtering, Alteration zones, Ahar