JOURNAL OF ANALYTICAL AND NUMERICAL METHODS IN MINING ENGINEERING
Year:2019 | Volume:9 | Issue:19 |Papers Count:11

Summary: Tunneling under the water table is a compatible condition for projects. Most important consequences of tunneling in this situation are water inrush, bad working condition, mudflow, low advance rate, and humans injuring. Especially for TBM tunneling that required high investments funds, these hazards can impose high costs for a project. This paper estimates water inflow by the finite element method in the second part of Emamzade Hashem tunnel and providing risk management for these hazards using the FMEA method. Introduction: The second part of Emamzade Hashem tunnel is the longest road tunneling project in Iran that will be excavated by a TBM. TBM tunneling in hard rock and faulty zone have lots of hazards that may cause many stops in the project according to previous similar projects around the world. Risk management could classify hazards and make them predictable and controllable. Methodology and Approaches: In this paper, water flow ratio was estimated by numerical simulation with FLAC 2D. In the following, the classical risk of water inrush was calculated by the FMEA method with studding some similar projects. A fuzzy analysis was then applied to increase the accuracy of the results. To this end, after estimating water inflow for each section of the tunnel, the time and costs of each hazard were calculated by studying similar projects. Risk number was estimated and managed through the FMEA method based on the calculations. The reduction actions were suggested for the hazards with high-risk numbers. Results and Conclusions: The results of the study indicated that tunneling in the middle part of the tunnel has high risk due to high water pressure according to classical and fuzzy analysis. It has resulted that the performance of fuzzy analysis is higher than classical analysis.

Summary: This work is aimed to investigate the effects of joints configuration in a rock mass on validity of the deformation values obtained using equivalent continuum approach. For this purpose, discrete element method is utilized to numerically model complicated joint configuration comparing to in-built assumptions of equivalent continuum equations. Then, deformation components obtained by equivalent continuum solutions were compared with the results of discrete element numerical analyses and in-situ tests to demonstrate the effect of geometric parameters. Finally, these results are provided to evaluate validity of equivalent continuum relations in deformation analysis of non-orthotropic rock masses, unlike their assumptions. Introduction: There are two different techniques to determine deformation behavior of jointed rock masses: direct and indirect methods. Direct methods include laboratory tests on rock specimens and in situ tests on field rock masses. The overall characteristics of large-scale rocks are often not available through direct measurements due to lack of time and financial resources. Indirect methods consist of empirical correlations, analytical solutions and numerical modelling. Empirical methods are based on correlation between rock mass deformability and its classification indices such as rock quality designation (RQD), rock mass rating (RMR) and geological strength index (GSI). In spite of their simplicity, it is not possible to capture anisotropic and scale-dependent behavior of rock mass using empirical techniques. Analytical or closed-form methods consider rock mass as an equivalent continuum in which the deformation is the sum of deformation of the intact rock and deformation of the joint sets. These solutions are digest and simple, and only can be used to analyze deformation of regularly jointed rocks. Most of them are inapplicable when dealing with irregular joint systems which are more common in nature. On the other hand, numerical modelling is advantageous to study the effect of joint sets configuration on deformation behavior of a jointed rock mass, and can be used to determine the accuracy of closed-form deformation analysis of irregularly jointed rock masses. Methodology and Approaches: For analysis purposes, the applicability of equivalent continuum approaches in estimating deformation behavior of rock masses with three intersecting joint sets was studied. Two different cases were considered, namely, deviation of the intersection angle and dip direction of the second joint set. 3DEC software contains several different behavior models for intact rock in which one or more of them can be used depending on governing assumptions. According to analytical approaches, isotropic elastic and Coulomb slip models were assigned to intact rock and joints, respectively. Note that joints were prevented to deform plastically because the purpose was to study the elastic deformation of jointed rock masses using both analytical and numerical analysis. Results and Conclusions: According to the obtained results, following conclusions can be reported for the conducted study: Axial analytical and numerical deformation values have a high sensitivity to intersection angle but there is no evidence to know how they change with this parameter. Further deviation of intersection angle results in increasing difference of numerical and analytical lateral deformation in the direction perpendicular to intersecting joint sets. Low discrepancies were recorded for lateral strains parallel to intersecting joint sets strike while changing intersection angle. Therefore, it can be concluded that the application of equivalent continuum method to estimate this component would be somehow accurate. The effect of dip angle of intersecting joint sets is not considered in the non-orthotropic equivalent continuum approach. However, results generally show a considerable effect of this parameter on the discrepancy of analytical and numerical values. Differences between analytical and numerical deformation results show that changing the dip direction does not significantly affect the results, but applicability of the corresponding equivalent continuum solution is questionable in some cases. Application of analytical equation for axial strain estimation is not recommended when dip angle of intersecting joint sets has a dominant contribution to deformation. In the case of dip direction deviation, lateral strain estimation parallel to joints strike through the corresponding analytical solution has an acceptable accuracy.

Summary: Geo-statistical modeling requires a high level of experience and precision that was formerly hand-made and nowadays is semi-computer or computer generated. Most of these models are based on interval data obtained from exploratory drilling cores and linear interpolation techniques. Nowadays, geo-statistical methods, especially indicator kriging, have been found to be highly capable of producing geometric-geological models but most of the time the changes in the geological micro-zones are gradual, and these models have various ambiguities, which is particularly important in the separation of alteration zones in porphyry copper mines. Introduction: Among the data provided during geochemical and geotechnical exploration drilling, the images of drill core boxes are important and comparatively inexpensive. In this study, the quantitative data of red, green and blue were separately used by processing these types of images and converting them into color interval data in the RGB system instead of using the qualitative geological log data. The operation was carried out in a C-Shop program called Core Processing and executed on 20 boreholes of Kahang copper mine. Then, a database of joint density and RGB color system with a lag of 2 meters was prepared. One of the main features of color data is the normality of their distribution function in this region. Methodology and Approaches: This geostatistical study also yields the validated spherical variograms. Initially, a model for the Kahang Mine with a dimension of 700 × 300×400 m was developed and the values of R, G and B for rock blocks of 5 × 5 × 5 were estimated using ordinary kriging. This made it possible to obtain a real colors of geological section based on the triple RGB color system. For the verification of the validity of the proposed method, the color sections were compared with the lithology and alteration sections (already prepared by geologists) of Kahang Mine. For this purpose, a new index was defined as Irgb, which interpreting the length of the vector on the three axes R, G, and B (which did not show good agreement with the lithological sections). However, an acceptable similarity was obtained by comparing the alteration map in 1700 horizon with the Irgb index at the same level in Kahang Mine. Results and Conclusions: To ensure the feasibility of using the geostatistical model of RGB color system and the Irgb index another comparison was made at the Miduk Copper Mine and the colored model of this mine was prepared too. The tomography operation was performed in several profiles to determine the mine's hydro zones where the sections of electrical resistance coefficients were already prepared. These sections were then compared with the Irgb index sections prepared from the RGB model proposed in this study. The comparison was able to detect and distinguish alteration zones due to the sensitivity of the color to the alteration and also to prevent zones with low electrical resistance from being considered as hydro zones by mistake.

Summary: In this paper, by using the mines information of Iran provinces and singular value decomposition, the provinces of Iran are clustered. By using these clusters information, a recommender system is developed to help geologists and mining engineers. Introduction: Mining exploration consists of prospecting, early exploration, detailed and complementary stages (even extraction process). Prospecting stage begins with gathering and studying the information of mining area and preliminary sampling. Based on thumbnail technical and economic review, the feasibility of entering the preliminary stage of exploration is realized. At the start of prospecting stage, the total capacity of the area for production of significant and economic mineral deposits must be identified. Usually detecting of valuable deposits is performed according to information and experience of geologists and mining engineers. Therefore, the stage of exploration involves high cost and risk. Thus, the methods that can reduce costs and uncertainties are considered. On the other hand, there is a collection of data related to the studied area and its surrounding with high dispersion that their analysis can lead researchers to the aim. By using mathematical methods in data mining such as clustering data, the mines with specific deposits according to similar geological conditions could be classified. Methodology and Approaches: Singular value decomposition is one of the most powerful tools in mathematics. This method is widely used in clustering problems and recommender systems. In this paper, at the first stage, the provinces of Iran are clustered by using singular value decomposition and metal mines data which are extracted from the mines database. The provinces in the same clusters are similar in geological conditions. Finally, recommender system for exploration of a specific mine, the provinces that are in the cluster having higher number of this mine are allocated top priority. Results and Conclusions: The results show that by using singular value decomposition and the mines information of Iran provinces, the provinces can be clustered. Moreover, the provinces in the same clusters, are similar in geological conditions. It is expected that, if a mineral deposit was discovered in a province, it would be found in another province in the same cluster too.

Summary: In present research, GPR method has been used to identify geometrical parameters of buried cylindrical targets. To achieve this goal, first forward modeling of GPR data has been carried out for several synthetic models corresponding to common targets in geotechnical and subsurface installations. Afterward, an applied algorithm on the basis of signal processing on a radargram (A Scan) with high accuracy was implemented in MATLAB environment. The performance of the algorithm was validated for several synthetic models so that led to the favorite results in all cases. The primitive algorithm was improved to employ for real GPR images having a large amount of various noises. Introduction: One of the most important tasks in engineering design is extraction of geometrical parameters of subsurface hidden objects. In this research, has been attempted to investigate the treatment of GPR responses in spatial domain using simulated response of various synthetic models by forward modeling. Then after extraction of relationships between existence mathematical models with GPR system response, geometrical parameters of buried cylindrical targets and physical parameters of host medium are identified through employing appropriate algorithms and image processing methods. Methodology and Approaches: An applied algorithm based on signal processing on a radargram (A Scan) was implemented in MATLAB environment which investigates the treatment of GPR response in spatial domain. The performance of the algorithm was validated for several synthetic models such as empty metallic and PVC horizontal cylinders and also the model including the couple of empty horizontal cylinders made by PVC. The algorithm was improved by applying Cascade Object Detector (COD) algorithm, interest of region is defined so that null regions are removed, implementing on the finite interested region. Then the algorithm is trained based on definition of positive and negative images. The performance of the proposed algorithm was evaluated for a real GPR radargram related to one of the profiles surveyed in Imam-Hossein square, opposite the municipality of Isfahan city so that also yielded a favorite result in this regard. Results and conclusions: In order to evaluate the accuracy of curve fitting the hyperbolic equation on the data, statistical validation criterion well-known as determination coefficient has been used. According to this criterion fitting accuracy of hyperbolic equation on the data for all synthetic models except the couple of horizontal cylinders is up to 93 percent. The algorithm has estimated the geometrical parameters of cylindrical targets with an error less than 8 percent. Also using the improved algorithm, determination coefficient of the fitted curve is 83. 99 percent that is a favorite result. The algorithm could estimate radius, burial depth and horizontal location of the buried horizontal cylinder in the real GPR image with the errors of 7. 6, 1. 7 and 1. 1 percent, respectively.

Summary: The numerical study of airflow has mainly concentrated on underground mines and road tunnels. Ventilation during the construction of long tunnels, especially the ventilation of TBMs, has received less attention. This paper aims to study airflow pattern in TBMs with regard to safety and as such reduce dead zones area. The results show that the airflow pattern of a TBM ventilation system, which can help to design an effective ventilation system for the TBMs. Introduction: The Tunnel Boring Machines (TBMs) has revolutionized the tunneling industry to create underground space safer, healthier and more economical. Ventilation is one of the main components of mechanized tunneling. The airflow quality and the related mass flow rate in the ventilation system should be sufficient to dilute gases and remove the dust inside the tunnel. Since most of TBM crews stay and work in the mainframe area, ventilation of this zone is very important. Methodology and Approaches: In this study, we modeled the TBM ventilation system using CFD method to understand airflow behavior in TBM. Numerical solution of the governing equations and boundary conditions are performed by utilizing the commercial CFD code Ansys CFX 18. 1. Tests of mesh-independence were conducted based on four different meshing creations. To define the boundary conditions, airflow velocity sampling was performed using multi-point sampling method in the ductwork outlet. To complete the discretization of the advection term, the high-resolution scheme was computed. Root Means Square (RMS) < was considered as the convergence criterion of mass and momentum equations. Results and Conclusions: The results show that there is not enough air flow in 89. 2% of TBM space in its current state. There are many dead zones from control cabin to the end of mainframe. The main direction of the back airflow moves along the segment feeder and increasing air mass flow has no effect in decreasing dead zones area. The results from the study present show that by increasing the air mass flow rate by 60% the volume of the dead zones in TBM is decreased by 13. 42% and has no effective decrease dead zone in the personnel breathing zone. The results from the present study clearly indicate that maximum mass flow capacity of jet fans is not possible to reduce dead zones that will only increase energy costs.

Summary: Comprehensive geochemical study shows the genetic relationship between 14 samples of gas condensates from the Persian Gulf. In this study, the samples were examined merely in terms of maturity, which led to a general trend towards maturation of the region. In this process, maturation increases from west to east of the Persian Gulf and also from the coastal Fars to the Persian Gulf and then to the Arabian section. Introduction: By using data collected including data biomarkers derived from gas chromatography-mass spectrometry analysis to provide relevant diagrams for maturity and source rock sedimentation environment, as well as statistical analysis of existing samples for all fields, which ultimately, by matching the interpretations of these two to the desired results, the purpose of this Research has been achieved. Methodology and approaches: The Samples were collected from Dalan and Kangan reservoirs (Late Permian – Triassic) from 6 gas fields (gas condensate), Which constitute the most important Iranian gas/gas condensate reservoirs. In this study, in order to estimate the maturity of samples (for the purpose of determining the thermal maturity of gas condensates and determining their range of placement in the maturity chart), as well as determining the sedimentary environment of the source rock and type of lithology, the available biomarker parameters obtained from the results gas chromatography-mass spectrometry (GC-MS) were used. The statistical methods used are agglomerative hierarchical clustering (AHC) and principal component analysis (PCA), which show that the studied gases are in three main genetic groups. Results andConclusions: According to the results of this study, the origin of hydrocarbons in the region of marine organic matter with some organic matter of continental origin, which maturity range is in the late stages of petroleum production and early gas window. This gas condensate is derived from the clastic lithological sources that have been generated under reducing environmental conditions and from type II and III kerogens. The three main groups of gas condensate from statistical analysis and make correlation to the source rock were identified using biomarker parameters related to maturity and sedimentation environment. The maturity from the Golshan field to the Salman field (from west to east of the Persian Gulf) increases and the sedimentary environment is different in the southern Persian Gulf Salman and Golshan fields (marine carbonate) from its northern fields such as Khayyam, Tabnak and Madar (marine shale).

Summary: Chromite exploration is really important in mineral exploration. Gravity method is really important in chromite exploration. Edge detection methods are used to determine lenses of chromite. In this paper, we used the curvature gravity gradient tensor (CGGT) along with the tilt angle method to detect chromite lenses. Application of the methods on synthetic and real gravity data showed that the CGGT can determine the edges of chromite lenses better than the tilt angle method. Introduction: Chromite is a strategic mineral. Therefore, the exploration of chromite mineral reserves is the main mineral exploration priorities. Chromite has a marked density contrast with the host rock, so the gravity method can be applied for exploration of the chromite ore bodies. The boreholes locations are usually determined after finding the edges of the chromite lenses by edge detection of the gravity anomalies. There are various edge detection methods. Most of the edge enhancement techniques are interpreted qualitatively. The Tilt angle method is a traditional method that can detect edges of subsurface structures quantitatively. The value of Tilt angle is zero above edges of subsurface bodies. The curvature gravity gradient tensor (CGGT) was also used to interpret the geological structure quantitatively. The value of eigenvalues of CGGT are zero above edges of subsurface bodies. In this paper, we used CGGT for edge detection of chromite lenses. Methodology and Approaches: In order to obtain CGGT, at first, horizontal vector gradients of gravity gradient tensors are computed from the vertical component of gravity data with a Fourier transform technique. Then the eigenvalues of CGGT are obtained. The large eigenvalue determines the edges of negative density bodies while the small eigenvalue only can be used to outline edges of positive density bodies. The chromite has positive density contrast with the host rock and produce positive gravity anomaly. Therefore, we choose the small eigenvalue to outline edges of the chromite lenses. Finally, the tilt angle is also applied to compare with the CGGT. Results and Conclusions: The robustness of the codes used for the edge enhancement is tested with gravity field anomaly map caused by four prisms of synthetic bodies. The results indicated that the proposed method can enhance the edges of the synthetic bodies with zero contour of the small eigenvalue of the CGGT. Then, the proposed method has been applied on the real gravity data from chromite deposits In Camaguey province, Cuba. The results showed that the zero contour of the small eigenvalue of the CGGT can outline the edges of synthetic bodies and chromite lenses better than the zero contour of the tilt angle method. Therefore, we can use the small eigenvalue of the CGGT to detect edges of chromite lenses precisely.

Summary: In this paper developed a model by COMSOL software that able to predict operational parameters effect on the components and heating value of produced gas during underground coal gasification. In this model for shown the effects of Operational Parameters on UCG process a Case Study has been developed. The results show that this model able to predict the effects of operational parameters on the components and heating value of produced gas in UCG process. Introduction: Underground Coal Gasification (UCG) process have a good adaptation with environment, in this process at the first insitu-coal seam converted to syngas and then would be explorated. The main purpose in UCG process is producing syngas with a heating value or producing each gases that producing in UCG process (for example Hydrogen production). Before implement of UCG process, predict of the components and heating value of syngas is necessary to economic analysis. In this paper presented a new model to gasify all coal in each stope, however; the produced gas have a high heating value. Methodology and Approaches: According to this model, moreover to gasify all of coal in each stope, the extent of heating value of produced gas is the same requested amount. Presented model in this research have been introduced with a Case Study for K10 coal seam of Takht region. Finally Operational Parameters to produce syngas with appropriate components and heating value for gasify K10 coal seam is calculated (it should be noted that this design shows only one possible scenarios). Results and Conclusions: The results for this case study shown that in a period of 11 months, 9 stopes must be active simultaneously and Operational Parameters in each stope including temperature, cavity pressure, oxygen injection rate, steam injection rate and operation time should be consider 1273K, 1MPa, 10 mol/s, 20 mol/s and 11 months respectively. In this case, K10 coal seam can support feed of 27 MW IGCC-based power plant for 22 years.

Summary: In this paper, in-operation mines of Azerbaijan-e-Gharbi Province, as a mineral-rich province of Iran, are ranked using multi criteria decision making methods. However, in this study, the analyses are done under the fuzzy environment to reduce the ambiguous and uncertainties. The results of this study show that, the iron and gold mines are the first priorities, chromic and manganese mineral types are the second priorities and the lead and zinc mines are the third priorities. Introduction: Mines and mining industries are an important way to reach the sustainable development and investing in these sectors creates the suitable economics value added. Therefore, prioritization of the mineral activities are helpful for persuasion of future investments. The main aim of this research is to rank the mining activities of the Azerbaijan-e-Gharbi Province in Iran with considering five main criteria including economic, cultural and social, environmental, technical and also political criteria. Methodology and Approaches: In this study, the main in-operation mines are considered. The technique for order of preference by similarity to ideal solution and also the analytical hierarchy process are used to prioritize the mining activities. To reduce the uncertainties, all calculations are done under the fuzzy environment. Results and Conclusions: Results of this study show that, the cultural, social and environmental criteria have the highest importance degree in comparison to the other criteria. The iron and gold mines are the first priorities, while the chromic and manganese mines and lead and zinc mines are respectively the second and third priorities. The quarry and gypsum mineral types, the barite, red and yellow soil, kaolin, fireclay and dolomite, salt and silica, sand, rubble, mica, limestone and ballast mines are respectively ranked also.

Summary: Piled-raft foundation is a complex system that overall load divided between the piles and raft upon pile-soil-raft interaction, in which piles mainly act as settlement reducer. Piled-raft foundations with different piles arrangement and soil type, i. e. medium clay and dense sand, were modeled in 3-D finite element software, PLAXIS 3-D Foundation. Influence of piles on differential settlement depends on the piles arrangement and soil properties. The numerical results showed that in two adjacent foundations on sand under uniform surcharge, when corner piles was removed and placing longer piles about their symmetry axes, the foundation settlement and rotation decreased considerably, at least 50%. For piled-raft foundation on soft with placement of longer piles in the center raft and shorter piles out of center, the optimal piles arrangement was achieved, while in dense sand piles concentration in the central region of raft was optimal arrangement. These later results obtained from rafts on clay and sand with different surcharge that has been analyzed to attain equal 154mm settlement. Introduction: One of the effective ways to improve the footing bearing capacity is using pile foundations. The piled-raft foundation is a new design concept as one of the effective methods of foundation to reduce settlements of structures. In piled raft foundation role of raft foundation is to provide adequate bearing capacity and role of pile foundation is mainly to act as settlement reducers. In this paper 3-D finite element analysis of piled raft foundations on dense sand and medium clay is studied. The purpose of the present study is to investigate the role of piles arrangement in reducing settlement of the piled raft foundation. Methodology and Approaches: Numerical method used for analysis of piled raft foundation, due to complex soil-structure interaction. A 3-D finite element software, PLAXIS 3-D Foundation utilized to analyze three dimensional models of piled raft foundation. The model results validated among settlements of Messe– Torhaus structure in Germany which was modeled in ABAQUS. Different pile arrangement plan in dense sand and medium clay was molded. Soil behavior was modeled by Mohr-Coulomb elastoplastic model. Results and Conclusions: Piles arrangement has a significant influence on the performance of piled raft foundation. Numerical results show that appropriate arrangement of piles which has maximum reduction in settlement strongly depends on soil type. Additionally, increasing the piles length has more influence on the performance of piled raft foundation, rather than pile diameter growth, when the volume of concrete in piles bodies has been constant.