Exploration and Mining
Kamran Mostafaei; Mohammadnabi Kianpour; Mahyar Yousefi
Abstract
This article is devoted to introducing a novel application of the Gray Wolf Optimizer in one of the most challenging issues related to mineral exploration, anomaly separation from the background in stream sediment geochemical studies. The Alut geological sheet, located in the Sanandaj-Sirjan zone, which ...
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This article is devoted to introducing a novel application of the Gray Wolf Optimizer in one of the most challenging issues related to mineral exploration, anomaly separation from the background in stream sediment geochemical studies. The Alut geological sheet, located in the Sanandaj-Sirjan zone, which has special importance to gold prospecting, has been studied for the distribution of gold and arsenic that accompany each other as the paracenteses in such deposits. The cost function used in this algorithm has been provided according to previously well-explored deposits. While the GWO algorithm was able to divide the sheet into two classes of anomalous and non-anomalous areas, the fractal method identified four categories among distributions of gold and arsenic, which impose the responsibility of selecting anomalous areas on the scientists. Obviously, the GWO draws the areas as potential zones of prospecting that may be neglected by fractal strategy. The derived results show that 24.8ppm and 15.7ppb is anomaly threshold for arsenic and gold distribution respectively. The comparison of the results shows that the anomaly threshold obtained by the fractal methods and GWO algorithm for arsenic is almost the same, but the anomaly threshold for gold in the GWO algorithm method is optimal.
Exploration and Mining
zohreh boroumand; Hadi Abdollahi; Reza Shahbazi; Shabnam Asl Pashaki; MirSaleh MirMohamadi
Abstract
Microbial-leaching of nickel from two arsenide ores (low- and high-grade samples) was precisely investigated. The microbial leaching of nickeline was accomplished with the admixture of mesophilic cultures in shake flasks with pulp densities of 0.5, 1, and 5% as well as 0.5, 1, and 3% respectively. The ...
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Microbial-leaching of nickel from two arsenide ores (low- and high-grade samples) was precisely investigated. The microbial leaching of nickeline was accomplished with the admixture of mesophilic cultures in shake flasks with pulp densities of 0.5, 1, and 5% as well as 0.5, 1, and 3% respectively. The nickel content was over 99% dissolved by mesophilic bacteria of low-grade and high-grade samples after 10 and 28 days respectively. In addition, three heterotrophic bacteria isolated from iron mine wastewater and tailing were used for bio-leaching of low and high- grade nickeline bearing arsenic ores. Three bacteria strains were investigated for their ability to leach from nickeline samples in different pulp densities (0.5%, 0.8%, 1.1%, and 3%)., Glutamicbacter nicotiana was more effective than the other strains. The Glutamicbacter nicotiana extracted Ni 100%, for the low-grade sample and up to 70 for the high-grade sample, respectively. The catalytic effect and galvanic interaction of different additives on the dissolution of the samples were investigated. In the low-grade sample, all four additives in both low-grade samples showed a positive efficiency. In high-grade, three of the four additives (silver-pyrite and L-Cysteine) had a positive effect on the dissolution of nickel.
Exploration and Mining
Amir Salimi; Samaneh Barak; Mahyar Yousefi
Abstract
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical ...
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An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical data of the Neysian region. The optimal U-values obtained by this method for each sample were successfully utilized to separate the abnormal and background samples, accurately. In addition, based on the optimal distance of each sample, the abnormal samples identified in the previous step were classified in terms of geochemical intensity into strong, medium and weak samples. The goodness of U-spatial statistics performance in identifying abnormal areas were validated using drilled boreholes in the area. The U-spatial statistics not only succeeded in correctly identifying anomalous samples, but it also correctly identified some samples as the background whiles they had been recognized as anomaly by a non-structural method. All results obtained were validated by the several drilled boreholes.
Exploration and Mining
Keytash Moshtaghian; Seyed Mohammad Abtahi Forooshani; Hooshang Asadi Harooni; Mohammad Hajheidari; Ghazal Janghorban
Abstract
The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed ...
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The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed in the region. In the current study in the northern index, first, we extracted the local anomaly via removing the regional and aliasing effects from the magnetic data. Then, using three-dimensional inverse modeling of the reducted data illustrates the presence of a body with high magnetic susceptibility, in the depth range of 40 to 640 meters of the study area. A comparison between geochemical analysis of two exploratory core drilling with the depth variational model of the estimated magnetic susceptibility in the study area indicates a spatial correlation between increases in the grades of copper and gold and large variations of the magnetic susceptibility. Also, comparison between the magnetic susceptibility model and resistivity and chargeability models estimated from IP/RS data of three parallel profiles indicates a relation between sulfidic and altered mineralized zones and magnetic susceptibility variations. Therefore, the current study shows a high potential for the copper-gold mineralization in the northern Dalli index.
Exploration and Mining
Amin Jamshidi
Abstract
Accurate estimation of the rotary drilling rate of the rock can save time and cost on exploration operations of the geotechnical projects such as dams, tunnels, oil and gas wells and building stone mines. In this study, the rotary drilling rate in limestone is estimated based on brittleness indices. ...
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Accurate estimation of the rotary drilling rate of the rock can save time and cost on exploration operations of the geotechnical projects such as dams, tunnels, oil and gas wells and building stone mines. In this study, the rotary drilling rate in limestone is estimated based on brittleness indices. To achieve this goal, the values of rotary drilling rate, Uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) were determined in three exploratory wells drilled in limestone. Based on the data, the regression relationships of one, two and three variables between rotary drilling rate as a dependent parameter and brittleness indices as an independent parameter were developed. The results suggest that based on one- and two-variable regression relationships, rotary drilling rate can be estimated based on brittleness indices with relatively good accuracy. In addition, the results showed that the three-variable regression relationship was more accurate than the one- and two-variable in estimating the rotary drilling rate. Finally, the three-variable relationship presented in this study could be appropriate in the early stages of exploration operations for geotechnical projects in limestone, which saves time and money.
Exploration and Mining
Shahram Ghasemi; Mashalah Khamehchiyan; Mohammad Reza Nikudel; Ahmad Zalooli
Abstract
Joints and cracks are an integral part of rock structures. When load applied to these structures, growth, and interaction of the cracks lead them to failure. This aspect is particularly crucial in cyclic loading because failure occurs at stress levels lower than the yield point due to the fatigue process. ...
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Joints and cracks are an integral part of rock structures. When load applied to these structures, growth, and interaction of the cracks lead them to failure. This aspect is particularly crucial in cyclic loading because failure occurs at stress levels lower than the yield point due to the fatigue process. This research aims to study the growth and interaction of the cracks in the fatigue process by the fluorescence thin section method. At first, different stages of fatigue for granite rock were determined, then samples loaded up to each stage. Later, the physical, mechanical, and crack properties of the samples were investigated. The results show that physical and mechanical properties declined by increasing the number of cycles. During the first stage of fatigue, crack initiated at a high rate, and in the second stage, the increasing rate descended, and energy mostly consumed to increase the length of the cracks. In the last staged, which is the failure stage, the rate of crack initiation increases again and forms a complicated network of cracks, which leads the sample to failure. Among the constituent minerals, feldspar exhibits the highest crack density, and biotite shows the lowest density of the cracks.
Exploration and Mining
Iraj Rahmani; Erfan Sadeghi; Mohammad Reza Nikoodel
Abstract
Sedimentary rocks are the most common rocks exposed on the Earth’s surface and most of the civil structures are located on them, so the identification of these rocks have great importance. This recognition is more important in destructive environments such as beaches. One of the most important ...
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Sedimentary rocks are the most common rocks exposed on the Earth’s surface and most of the civil structures are located on them, so the identification of these rocks have great importance. This recognition is more important in destructive environments such as beaches. One of the most important factor on the engineering parameter results is the age of sedimentary rocks. In this study, beside the evaluation and field study of breakwaters in the southern and northern coasts of Iran, lithological and structural characteristics of materials were studied. Also, the purpose of this study was to determine and evaluate the engineering properties of stone materials based on engineering experiments to help evaluate durability and compare them with the results of field evaluation of actual rock performance. But the most important part of studies is to evaluate the effect of rock ages on the results and performance of these materials. The results show that materials with a siliceous composition such as sandstone compared to carbonate materials are the same in geological age. Also, increasing the age of rock materials (from Pleistocene to Cretaceous) causes an increase in rock density (from 1.59 to 2.45 g/cm3), reduced porosity (from 44.7 to 0.41%) and water absorption (from 29.6 to 0.21%), increase in strength parameters including increase in uniaxial compressive strength (from 5 to 111.19 MPa), increase in point load test (from 1.2 to 5.12 MPa) and increase in tensile strength (from 0.10 to 16.56 MPa) and decrease in durability due to abrasion, impact and chemical processes, including decrease in impact value (from 54.30 to 10.94%), increase in slake durability index (from 82.10 to 99.44%), a decrease in soundness (from 28.50 to 0.038 %) and a decrease in Los Angeles abrasion test (from 71.57 to 22.67%).
Exploration and Mining
Mojtaba mohammadi; Seyed Mahmoud Fatemi Aghda; Mehdi talkhablou; َAkbar Cheshomi
Abstract
Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding ...
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Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding the geotechnical characteristics and subsurface development of these sediments are essential in the old sedimentary environment for a couple of reasons. Firstly, it is difficult to determine the geotechnical characteristics of coarse-grained sediments and there is uncertainty in the subsurface development of these sediments at distant locations from the Zayandehrood river. Secondly, it is development of construction and the necessity of digging underground spaces Therefore, in this study, using the geotechnical data of 384 boreholes, maps of the approximate range of coarse-grained sediments of the Zayandehrood River were prepared at depths of 5, 10, 20 and 30 m and their geotechnical characteristics were statistical analyzed by the results of laboratory and in situ tests. The results show that the geotechnical characteristics of coarse-grained sediments do not change significantly with the change of depth and the approximate range of subsurface expansion of this river has been in the past in places other than the present river route.
Exploration and Mining
Mehdi Talkhablou; Mehdi Kianpour; Seyed Mahmoud Fatemi Aghda
Abstract
In this study, the efficiency of the compressive wave velocity (Vp) geophysical method for predicting the quality of limestone mass in areas of Zagros formation, has been investigated. For qualitative classification of limestone rock masses, the Q classification system and its modified classification ...
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In this study, the efficiency of the compressive wave velocity (Vp) geophysical method for predicting the quality of limestone mass in areas of Zagros formation, has been investigated. For qualitative classification of limestone rock masses, the Q classification system and its modified classification system for sedimentary rocks (Qsrm) have been used. For this purpose, the data related to Vp, Q and Qsrm were extracted at the site of Karun 2, Karun 4, Khersan 3 and Tangeh Manshoureh dam sites and by using software interpolation methods in ArcGIS has been transformed into information layers. Using simple and multivariable regression analysis on data extracted from information layers and using Fuzzy Inference System (FIS), models for predicting Q and Qsrm in calcareous rock masses are presented. Also, to evaluate the accuracy of the obtained models, in addition to R2, performance indicators (VAF) and root mean square error (RMSE) were used. The results show that since the Qsrm index considers a wider range of massive properties, the prediction of the Qsrm value is closer to reality using geophysical methods than the Q index.
Exploration and Mining
Hassan Bakhshandeh Amnieh; Amirhossein Rostami; Kurosh Shahriar; Hamid Chakeri; Masoud Cheraghi Seifabad
Abstract
When a tunnel passes through weak soil with different conditions, or there is a thin layer of soil on top of the tunnel, the mass of soil or rock must be stabilized. In addition, an excavation method must be chosen and applied in order to control the amount of subsidence and convergence which are among ...
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When a tunnel passes through weak soil with different conditions, or there is a thin layer of soil on top of the tunnel, the mass of soil or rock must be stabilized. In addition, an excavation method must be chosen and applied in order to control the amount of subsidence and convergence which are among the most significant factors in excavation a tunnel especially in urban area, since the soil between the tunnel and the ground moves due to changes in the shape of the tunnel through excavation, and progression of these movements toward the ground is manifested in subsidence of the surface structures. Therefore, in order to choose an excavation method based on the conditions of the project site, providing a decision-making model is essential. The ultimate goal is to select the most suitable subway tunnel excavation method among all available alternatives based on some determining criteria for Isfahan subway tunnel (Line 1). These criteria along with Multi-Criteria Decision Making (MCDM) models helped prioritize suitable alternatives. This model was designed based on technical, financial, executive, social, political and geo-mechanical features of the research site each of which subsumes a number of criteria. On the one hand, alternatives include Open Shield (full face) method, Slurry method, NATM method and excavate twin tunnel with TBM method which are used in the model. Finally, alternative D (excavate twin tunnel with TBM method) was selected as the best alternative of the site in both AHP(D=0.225) and TOPSIS(D=0.676391).
Exploration and Mining
Yaghoob Zarei; Ali Uromeihy; MohammadReza Nikoodel
Abstract
In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring ...
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In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring direction was created in each sample, and the wave velocity tests were repeated. These tests were continued up to 5 joints with two sets of 2 and 5 cm spacing. Consequently, the data were analyzed using the statistical methods. The results show that the P-wave velocity was decreased by increasing the number of joints in both spacing sets, and thus an inverse linear relationship was obtained. However, as the number of joints increases, the reduction rates of wave velocity were different at two spacing sets. More precisely, up to 3 joints, the reduction rate in the 5 cm spacing set was more than that in the other set. Nonetheles, after the third joint, the decreasing rate in the 2 cm spacing set became greater. Generally, the shorter spacing had a more reduction (attenuation) in the P-wave velocity. In this regard, at a total of 5 joints, the reduction rate of the P-wave velocity in 2 cm spacing set was more than that in the other set.
Exploration and Mining
Maliheh Abbaszadeh; Ardeshir Hezarkhani; Saeed Soltani-Mohammadi
Abstract
In recent years, economic geology studies have become very popular method in mineral exploration studies. Modeling fluid inclusion data is one of the common studies in economic geology. In this research artificial neural networks method, as one of the machine learning algorithms, is used for three-dimensional ...
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In recent years, economic geology studies have become very popular method in mineral exploration studies. Modeling fluid inclusion data is one of the common studies in economic geology. In this research artificial neural networks method, as one of the machine learning algorithms, is used for three-dimensional modeling and application of the results of fluid inclusion analysis in Sungun porphyry copper deposit. For this purpose, fluid inclusion data is used for directly separation of related alteration zones with mineralization (Potassic, Phyllic and Potassic- Phyllic). Due to the relation that exists between alteration zones and mineralization areas, based on 173 fluid inclusion data the separation of alteration zones is modeled by artificial neural networks method in Sungun porphyry copper deposit. According to the validation studies, it can be concluded that precision of this model is appropriate (83%) and trained model could be used for separation of alteration zones in Sungun porphyry copper deposit.
Exploration and Mining
Saeid Ghasemzadeh; Abbas Maghsoudi; Mahyar Yousefi
Abstract
The Baft district in Kerman province is located in the southeastern segment of the Urumieh-Dokhtar magmatic arc. This arc is characterized by thick accumulations of Cenozoic plutonic and volcanic rocks and provide favorable conditions to the development of hydrothermal systems and mineral deposition, ...
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The Baft district in Kerman province is located in the southeastern segment of the Urumieh-Dokhtar magmatic arc. This arc is characterized by thick accumulations of Cenozoic plutonic and volcanic rocks and provide favorable conditions to the development of hydrothermal systems and mineral deposition, in particular porphyry copper mineralization. For mineral prospectivity mapping (MPM) to delineate prospective areas some individual maps of evidence including distance to intrusive contacts, fault density, distance to hydrothermal alterations and multi-element geochemical signature were generated. Spatial evidence values in each map were transformed using a logistic function of unbounded values into the [0,1] range. Thus continuous maps of fuzzy evidence layers were integrated using geometric average function. To evaluate results of final potential map a data-driven prediction-area was used. The results showed that for the geometric average prospectivity model, 87% of the known mineral occurrences are predicted in 13% of the study area. Hence, this method can be utilized for mineral prospectivity mapping to delineate target areas for further exploration of a certain deposit-type.
Exploration and Mining
Ghodratollah Rostami Paydar; Hani Asadi Hoveizian
Abstract
Determination of relationship between rock mass properties concerning to rock qualification design (RQD) has an important role in mine planning and designation. The aim of this study is separation of rock mass properties to designing the mine planning based on the 3267 RQD data analysis of 43 drill-core ...
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Determination of relationship between rock mass properties concerning to rock qualification design (RQD) has an important role in mine planning and designation. The aim of this study is separation of rock mass properties to designing the mine planning based on the 3267 RQD data analysis of 43 drill-core within Zarshuran gold deposit in Orumieh- Dukhtar assemblage zone applying RQD-Number and RQD-Volume fractal modeling. The results of log-log plots for RQD-N model revealed four rock populations that divided by RQD thresholds 20.41, 47.86, 69.18 and 81.28. The results of log-log plots for RQD-V model release four populations divided by RQD thresholds 21.37, 43.65, 63.09, 79.43 respectively which represent very poor, poor, fair and good rocks based on Deere and Miller rock classification. In other hand the lithological units modeled based on the drill-core data to obtain the spatial distribution of Zarshuran deposit. The results of RQD-N and RQD-V fractal modeling versus lithological units modeling results revealed that Chaldagh limestone unit and Jaspiroid unit shows fair and good quality with RQD fractal value 69.18 till 81.28 and located at the center and western part of Zarshuran deposit. Therefore, in mine slop designing and planning have excellent conditions. The results of the RQD-N fractal modeling in Zarshuran deposit can usage as a practical method in similar districts.
Exploration and Mining
Ali Aalianvari; Saeed Soltani-Mohammadi; Maryam Miri
Abstract
The main objective of this paper is to estimate water seepage from the Azad dam foundation, based on the combined geotechnical investigations and multivariate geostatistical methods. Geological filed investigations and records at the 38 exploratory boreholes have been considered as the main source for ...
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The main objective of this paper is to estimate water seepage from the Azad dam foundation, based on the combined geotechnical investigations and multivariate geostatistical methods. Geological filed investigations and records at the 38 exploratory boreholes have been considered as the main source for seepage calculations. Due to expansion of reservoir and a few boreholes and limitation of geological investigations, distribution of permeability and permeability changes in the reservoir area is not an indicator for reservoir. In this research using geostatistical method (Kriging), Lugeon values have been estimated for abutments and foundation of the reservoir. Afterward, seepage was estimated for reservoir by using numerical method (FEM).results show that around 450 lit/min water was seepage from the dam. That is very close to the observed seepage from dam foundation. Based on the results, the total seepage estimated is around 450 lit/min that is relatively closed to the observed and measurements flow (350lit/min).
Exploration and Mining
Mohammad Hassan Nazari; A. Uromeihy
Abstract
There are several outstanding factors engaged in the cement grouts filtration. These factors can be evaluated from some aspects including the characteristics of the grout, cement and grouting materials, grouting environment, interaction between the grout and environment and grouting pressure among which ...
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There are several outstanding factors engaged in the cement grouts filtration. These factors can be evaluated from some aspects including the characteristics of the grout, cement and grouting materials, grouting environment, interaction between the grout and environment and grouting pressure among which fewer studies have been performed on the role of the grouting pressure in the grout filtration. In this research practical results of cement grouting have been reviewed in two dam projects as examples. The results depict that the increase in the grouting pressure considerably affects the rate of cement take and penetration. In practice, the cement penetration into the rock is higher when the grouting pressure is variable. This is vice versa under constant grouting pressure. In other words, the increasing steps of grouting pressure may erode the grout cake at each stage. This leads to optimal penetration of the grout and decreases the watertightening costs of the dam foundation, tunnels and structures requiring cement grouting.
Exploration and Mining
Ayyub Nikkhah; Mohammad Taji
Abstract
In open pit mines, the extraction of ore rock with minimum price and good quality is the most important mining goal. In this paper, the impact of underground water on production costs and mining process has been investigated. For this purpose, the parameter specific crushing(S_cr ), measured and used. ...
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In open pit mines, the extraction of ore rock with minimum price and good quality is the most important mining goal. In this paper, the impact of underground water on production costs and mining process has been investigated. For this purpose, the parameter specific crushing(S_cr ), measured and used. To evaluate mining operation in dry and wet conditions of database in two parts of production costs and mining operations of two blasts, holes with diameter of 6 inches were created. The difference of two different conditions of mining in increasing production costs and reducing production performance is observed such that the costs including drilling cost, blast cost, total drilling and blast costs, loading cost are increased respectively, equal to 83.33, 450, 266.67 and 200 percent in wet mining conditions compared with dry conditions. Rock crushing cost due to crushing amount is almost similar in both conditions. Also, wet mining conditions cause reducing the production yield of Sarcheshmeh copper mine such that production performance in sections including special loading and index specific mining operations unit has been decreased respectively, equal to 33.34 and 198.85 percent compared to dry conditions. In order not to use waterproof explosives, improvement of mining operations index and reduction of project production costs, it is necessary to determine the model of underground water of Sarcheshmeh copper mine. Desirable mining operation will be provided with lower cost with sustainable development by drainage of underground water in open pit mines.
Exploration and Mining
H. Bakhshandeh Amnieh; Amirhossein Rostami; Kurosh Shahriar; Hamid Chakeri; Masoud Cheraghi Seifabad
Abstract
Abstract In the urban tunneling project, one of the most important parameters to be considered is the subsidence level. Metro tunnels are one of the most important urban transportation infrastructures. Due to shallow depth of drilling, the most important factors to prevent the maximum subsidence and ...
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Abstract In the urban tunneling project, one of the most important parameters to be considered is the subsidence level. Metro tunnels are one of the most important urban transportation infrastructures. Due to shallow depth of drilling, the most important factors to prevent the maximum subsidence and subsequent damage of surface and subsurface structures are deformation control and shear forces. The various methods of estimating the subsidence are divided in three categories, namely; Empirical, analytical and numerical methods. In this research, according to the geotechnical conditions of the study area using the data collected from the monitoring during the excavation of twin tunnels of metro by TBM, the empirical methods for the subsidence ( s=A_2+s_max/2 ), the maximum subsidence (s_max=A_1-A_2 ) and the inflection point (ⅈ=x_0 ) are presented by using Boltzmann function for Isfahan twin metro tunnel. Keywords: Subsidence, Maximum subsidence, Inflection point, Empirical Method, Analytical Method, Numerical Method, TBM.
Exploration and Mining
Meysam Yazdani; Firouz Alinia
Abstract
Sehezar area is located in southern city of Tonokabon in Mazandaran province in north of Iran, and near the Tarom – Hashtjin belt. The existence of granitoid masses in the region can be important in terms of the potential of mineralization. The kriging geostatistical technique is used to predict ...
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Sehezar area is located in southern city of Tonokabon in Mazandaran province in north of Iran, and near the Tarom – Hashtjin belt. The existence of granitoid masses in the region can be important in terms of the potential of mineralization. The kriging geostatistical technique is used to predict the grade distribution, by using existing data and spatial correlation between them, which is described by the variogram. To identify the anomalous area, 50 stream sediment samples were collected from the area and analyzed by the ICP-MS method, and then interpreted. At first, the data were normalized and then the geostatistical analysis was used. Variogram studies showed that the spherical model is the best fitted model, and the spatial correlation range for the three elements of Au, Cu and Fe are approximately 350 m and for W is approximately 700 m. Finally, the estimation and estimation variance maps of the studied elements were prepared by using ordinary kriging geostatistical method with the spherical model on the GS+ software. Evaluating the results by calculating the root mean square error (RMSE) and calculating the mean absolute error (MAE) indicates the acceptable accuracy of variogram model. By studying the kriging estimation and kriging estimation variance maps, the anomal regions were introduced for the elements of Au, Cu, Fe and W in the case study. Due to the spatial correlation of the elements, it is concluded that this mass can be associated with iron-gold-copper deposits.
Exploration and Mining
Nazanin Mahbubi Motlagh; Ahmad-Reza Mahboubi Ardakani
Abstract
There are different methods to improve the technical characteristic of problematic soils. Stabilizing with lime and reinforcing by high tensile strength elements are among the improvement techniques.. The use of geosynthetics to improve the engineering properties of various types of soil is well accepted ...
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There are different methods to improve the technical characteristic of problematic soils. Stabilizing with lime and reinforcing by high tensile strength elements are among the improvement techniques.. The use of geosynthetics to improve the engineering properties of various types of soil is well accepted now. Most of the studies have been limited to coarse-grained soils and few studies has been done on the feasibility of geosynthetic reinforcement on cohesive soils. Due to the positive effects of adding lime to fine-grained soils and their reinforcement by geosynthetic, concurrent effects of these methods can develop the usage of fine-grained soils. In the current research, clay samples have been stabilized with 0, 2, 4 and 6 % of lime and reinforced with geosynthetic (geotextile and geogrid) and cured for 1 and 7 days and then subjected to direct shear test. To investigate the soil-geosynthetic interface parameters and reinforcement efficiency, the direct shear tests were done on reinforced samples with geotextile and two groups of reinforced samples with and without transverse members of geogrids. The test results reveal that stabilization with lime increases shear strength and it is also increased with curing time. The shear strength of reinforced samples is higher than that of unreinforced samples, and under the same normal stress the shear resistance of the soil reinforced by geogrid is higher than of that reinforced by geotextile. Under the same curing time, the highest shear strength and reinforcement efficiency is achieved in samples reinforced and stabilized with 4% of lime and they are also increased with increasing curing duration.
Exploration and Mining
V. Joudaki; F. Koohiyan-Afzal; A. Aalianvari; R. Ajalloeian; A. Sohrabi-Bidar
Abstract
Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some ...
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Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some limitations such as thick(up to 600 meters in some localities)overburden over the tunnel and the lack of exploratory drilling down to the tunnel level, it has been difficult to forecast and estimate the groundwater flow in the tunnel route. Due to the existence of numerous faults in part 4 of the Ghomroud tunnel ,encountering of the drilling machine (Double Shield TBM) with high-pressure water could cause influx of large amounts of water into the tunnel and collapse of rock masses in the crushed zones. It hence could cause deviation of the machine and drilling stop. In this article, the lack of data from boreholes led us to try investigating the development of groundwater flow in the tunnel based on geomorphological evidence. Analytical modeling and geomorphological field survey in the area show a relative consistency between geomorphology and volume of water flowing in the tunnel excavation. Therefore, according to measurements conducted on the water entering the tunnel, about 80 liters per second of water flowed into the tunnel, which is in agreement with geomorphological studies. Results show that the study of morphology and surface features could provide useful information in order to identify more precisely the hydrogeologic conditions of the area.
Exploration and Mining
A. Uromeihy; E. Sadat Razavi; V. Baghri
Abstract
Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active ...
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Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active faults, with the Khazar fault being regarded as the most effect one, which can produce a gravity acceleration of 0.3g for a major earthquake. According to geotechnical data from exploration boreholes, the ground surface along Line 2 of Metro in the city comprises mainly a sequence of silts and clays with interlayers of gravel and sand. Due to high level of groundwater table, abundance of fine-grained soils, high seismicity potential, and production of ground vibration during movement of the train, liquefaction can be expected to occur along the Metro line. The aim of this paper is therefore to evaluate the liquefaction hazard potential along the Line 2 of Metro of the Rasht City by preparing a hazard zonation map. Liquefaction hazard zonation mapping was carried out using data gathered from 14 exploration boreholes drilled to a depth down to 40 meters integrated into Analytical Hierarchy Process (AHP) in the GIS modelling system. In this regards, five layers of information including soil type, SPT number, overburden pressure, plastic index and maximum gravity acceleration were considered. The results indicate that the range of liquefaction hazard varies between low to very high, and the maximum rate of liquefaction is expected in BC2 and I2 stations (Sazeman-e-Ab and Husain Abad areas, respectively). Soil type and groundwater table are recognized to be the most effecttive agents in inducing potential liquefaction.