JOURNAL OF ANALYTICAL AND NUMERICAL METHODS IN MINING ENGINEERING
Year:2018 | Volume:7 | Issue:14 |Papers Count:10

summary: The Dalli area has been introduced as copper–gold probably porphyry mineralized area in the central part of Iran. In this study, in order to determine the mineralization pattern, a new method based on coupling discrete wavelet transform (DWT) and principal component analysis (PCA) has been used. The surface geochemical data of 30 elements were transformed to position – scale domain using 2DWT and were decomposed to high and low frequencies in one level then PCA was performed on vertical and horizontal detail components separately. In the final, the elements of Au and Cu have been classified clearly using the combination of mineralization factors obtained of vertical and horizontal detail components. The results of this study demonstrate that the DWT – PCA combined approach is a modern method for geochemical data processing. Introduction: In this paper, the position - scale domain of geochemical data, using 2dimensional discrete wavelet transform has been represented and analyzed on Cu–Au porphyry deposit in northern Dalli area and the results have been discussed. Wavelet analyses have led to very successful results in numerous scientific and engineering fields such as signal analysis and numerical applications. Methodology and Approaches: WT is a tool for the analysis of signals. Wavelets are used as the basis functions for signal representation such as sines and cosines. In the DWT, detailed and approximation coefficients are obtained with the wavelet algorithm based on high-pass and low-pass filters. In this paper, a new method is proposed based on coupling Haar DWT and Principal component analysis (PCA) for mineralization elements forecasting applications. PCA is a multivariate statistical method for geo-information identification of geo-datasets. Results and Conclusions: The wavelet coefficients of geochemical data in vertical and horizontal detail components have appropriate exploratory information. The results of this analysis on the Haar WT have desirably identified the mineralizing elements. Hence, the Haar wavelet is a suitable mother wavelet for interpretation of geochemical data. The surface information and the exploration drillings in the study area confirm the results of WT.

Summary: To date, given the importance of drilling operations in the mining process and its impact on other phases of extraction, a number of studies have been carried out to investigate the influence of predicted bit rate and to determine the parameters influencing it. The estimation of rate of penetration (ROP) is an integral part of the design and planning stages of a mining project. To achieve a reasonable estimation of the ROP in the rock, it is essential to identify the influential factors, measure the effectiveness, and calculate the uncertainty of each set. The factors examined in current study include thrust, rock mass characteristics including rock mass indices, uniaxial compressive strength of intact rock, Schmidt hardness. Conducting a field study and laboratory testing, a database was compiled from the above parameters in Irankuh mine. Among these parameters, Schmidt hardness has the lowest standard deviation and highest reliability index and thrust has the highest standard deviation and lowest reliability index. This result indicated that in the independent parameters, Schmidt hardness has the lowest and thrust has the highest level of uncertainty. The standard deviation and reliability index of experimental models presented for the (ROP) are also at 53.02 and 0.729 percent respectively. So this relationship to predict the (ROP) in the lead and zinc Irankuh mine is confidence. Introduction: In this research, the necessary parameters to predict the drilling speed were selected in order to examine the effect of different geological, geo-mechanical and operational parameters of the drilling machine on ROP and prediction of the performance of the drilling machine. The model was obtained from effective parameters for the penetration rate. In the following, the reliability rate of the obtained model was calculated for the rate of permeability of drilling-bit in Irankouh mine to examine the uncertainty rate. Methodology and Approaches: The first-order second-moment method has the calculations that are relatively simple, and only the information needed to calculate it, is information related to the moments of the input variables, so this method has been used in this research. Results and Conclusions: In this research, there is an uncertainty in registered information due to the environment to conduct the field observations and surveys and laboratory tests. Therefore, there is uncertainty and ambiguity in the developed equation to calculate the penetration rate in the Irankouh mine. So it has been tried to calculate the amount of ambiguity and, in fact, the number of variations that indicates the dispersion around the actual value of the penetration rate, using reliability analysis to FOSM first-order-second-moment method.

Summary: Principal Component Analysis (PCA) and Catchment Basin Analysis (CBA) methods have important role in investigation of stream sediment geochemical data and can have special contribution in prospecting programs and other exploration steps. In this study, the data of 843 stream sediment samples from Khoy 1:100,000 geological sheet area in West Azerbaijan, were investigated using PCA and CBA methods. At first, dimension of variables such as REEs as well as Cu, Pb, Zn, Cr, Au and Ag was decreased using principal component analysis (PCA) and the main principal components were selected for further investigation and finally the correlation of each parameter with achieved factors were given. Then, the background values were calculated and local anomalies were separated using catchment basin analysis on the basis of real area and upstream geological units of catchment. In addition, it is demonstrated that catchment basin analysis is able to better discriminate local anomalies. Consequently two mentioned methods obviously can validate each other. Briefly, in this research, the rare earth and other strategic elements in stream sediments samples of the Khoy 1:100,000 geological sheet area, have been investigated. The background values were calculated and local anomalies were separated using catchment basin analysis on the basis of real area and upstream geological units of catchment. Threshold level method was used for separation of anomalies from background. Also, by principal component analysis (PCA) method, the main factors were delineated. Results obtained from PCA method, were estimated using ordinary kriging and finally these two methods were compared. Consequently two mentioned methods obviously can validate each other. Introduction: Aggregation of elements in stream sediments depends on the stream network, area and topography slope of catchment and upstream lithological units. Investigation of these sediments using catchment basin analysis and principal component analysis methods, obviously introduces elements dispersion and prevents demonstrating unreal anomalies. The PCA method is useful in identification of complicated structure, indexing and reduction of data dimension. Because of existence of vast alluvial plains, alluvial fans, coasts and vast basins in Iran, geochemical data analysis by CBA method can lead us to explore the valuable mineral resources to reach sustainable development. The above mention methods will cause to find probable mineralization regions. Methodology and Approaches: In this study, for investigation of stream sediments geochemical anomalies, different steps such as data processing, separation of basins, calculation of local anomaly using CBA and PCA methods have been used for REEs and some other trace elements. In CBA method, the basins were separated by ArcGIS software and Archydro tools extension and then, real area of geological units for all catchments were calculated. Finally, using real area and application of upstream lithologies in given equations, the background values were calculated and local anomalies were separated. In PCA method, the main component of each elements were delineated, using ordinary kriging, values of each main factors have been estimated in unsampled regions. Results and Conclusions: Results and geochemical maps obtained by BCA and PCA methods demonstrate that catchment basin analysis is able to better discriminate local anomalies and these anomalies have been correlated with the ordinary kriging maps obtained from principal component analysis and these two mentioned methods, obviously can validate each other.

Since Iran is a rich country in copper resources, in order to track and introduce of prone mineral areas, using the applied methods with wide regional coverage such as satellite digital image data is inevitable thereby in addition to save time and cost, more potential region with acceptable precision for more accurate studies be elected. One of the most important cases which in preliminary step at satellite studies must be noted is environmental changes and surface effects that in related to these resources appear on surface of the earth which one of the most important is presence of alteration layers, how zones place related to each other, presence of Gossans layer and breccia zones.It is clear that according to diversity of remote sensing methods in studying of earth effects, all methods are not the same in terms of efficiency and performance and each method may be appropriate to introduce one effect of earth surface or alteration; accordingly, different methods of principal component analyzing, RBD, SAM and LA were used to compare efficiency and precision and performance of methods in introducing of alteration halos and Gossans. Also, with consider to importance of faults and linear structures on mineralization and alteration of different rock unites, linear structures were extracted using filtration method in different directions. The results, showed that the best regions for deposition of porphyry copper are the area with high density of lineation and the best results are achieved when during the filtering in vertical direction on main forces and stresses of the region. Then, in order to evaluation of accuracy and comparison of methods, 92 samples were obtained from alteration zones and mineralization area. Accordingly, it is found that SAM for introducing of Phyllic alteration type and advanced argilic is the best method and DPCA has the highest performance to recognize propylitic and gossans region.

Summary: Wellbore instability can increase drilling time and sometimes leads to wells being side-tracked. Appropriate estimation of the weight of drilling mud can be mentioned as the key designing factor to ensure the mechanical stability of wellbores. Considering the elastoplastic behavior of the medium, yield criterion plays a key role in this analysis and estimation. Applying the Mohr-Coulomb criterion leads to underestimation of rock strength due to ignoring the effect of the intermediate principal stress. On the other hand, the Mogi-Coulomb yield criterion is able to consider the effect of the intermediate principal stress, while preserves the simplicity of the Mohr-Coulomb model. In this study, the elastic - perfectly plastic constitutive model is developed based on the Mogi-Coulomb criterion. Model predictions for some triaxial tests are compared with experimental data, and reasonable agreement is achieved. The proposed model is also applied for analyzing a wellbore stability problem and results are compared with two popular models, Mohr-Coulomb and Drucker-Prager, to investigate the effect of the intermediate principal stress. Introduction: The simplicity of the Mohr-Coulomb criterion makes it as one the most popular models in geomechanical analysis. However, ignoring the effect of the intermediate principal stress can be mentioned as the main shortcoming of this model. On the other hand, the effect of the intermediate principal stress has been widely studied in experimental and analytical investigations. The Mogi-Coulomb yield criterion, not only overcomes this shortcoming, but also conserves the simplicity of the Mohr-Coulomb model. Alajmi and Zimmerman (2005) analytically showed the ability of Mogi-Coulomb criterion in considering the effect of the intermediate principal stress. This investigation showed that this criterion can introduce a more realistic estimation of rocks strength. Methodology and Approaches: An elastic-perfectly plastic constitutive model is developed based on the Mogi-Coulomb yield criterion. The proposed model is implemented to “FLAC”. Verification is done by simulating some triaxial test data. Numerical example is also conducted to investigate the efficiency of the model. Results and Conclusions: Results of the numerical study shows that the Mohr-Coulomb criterion results in underestimation of rocks strength by ignoring the effect of the intermediate principal stress. On the other hand, the Drucker-Prager criterion leads to overestimation of the strength by considering identical effects for both intermediate and minimum principal stress. While the Mogi-Coulomb criterion introduces a more realistic estimation of the strength by moderating the effect of the intermediate principal stress.

Summary: Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data and Interactive Data Language (IDL) logical operator algorithms with calculating threshold based on the land, and experimental laboratory analysis, were used to map hydrothermally altered rocks in the Sar Cheshmeh, Darrehzar, Nowchoon, Seridune and Sarkuh areas. Hydrothermal alteration enhanced by this method include silicic (hydrous quartz, chalcedony, opal), propylitic (calcite and epidote- chlorite), argillic (alunite-pyrophyllite-kaolinite) and phyllic (sericite-illite). By use of this method, different types of hydrothermal alteration in and around mineral deposits such as Sar Cheshmeh and Darrehzar, based on field observations and sampling, confirmed. Calcite and epidote- chlorite minerals were separated in the propylitic zone based on the logical operator algorithms.Introduction: Band ratios are based on the absorption and reflection parts of the electromagnetic spectra of minerals. In order to minimize the interferences from other sources such as vegetation cover, combined use of band ratios are suggested by different workers. Logical operators suggested by Mars and Rowan (2006) and Mars (2013) are used here for mapping different minerals associated with hydrothermal alterations. The important point in using these logical operators is the proper selections of the threshold for each alteration type. This point is discussed in this paper.Methodology and Approaches: ASTER data used for hydrothermal alteration mapping using the combined band ratio method. The combination of different band ratios with specified thresholds, is used to map hydrothermally altered areas. The threshold values are calculated based on both statistical method and field/laboratory observations. Finally, logical operators suggested by Mars and Rowan (2006) and Mars (2013) used for this purpose. The result will be a binary image based on true (presence of alteration, which is one) or false (absence of alteration, which is zero) for each pixel of the image. The alteration maps obtained are evaluated using field and laboratory observations.Results and Conclusions: By use of this method, different types of hydrothermal alteration in and around mineral deposits such as Sar Cheshmeh and Darrehzar, based on field sampling/laboratory observations, confirmed. In areas such as Seridune due to the weathering of host rocks, phyllic and argillic alterations are observed together. Calcite and epidote- chlorite minerals were separated in the propylitic zone based on the logical operator algorithms. Sampling results and field observations have confirmed the alteration maps.

Summary: Identification and modification of multivariate outlier data is the first step to analyze exploration data through multivariate statistics. A key to this problem is reducing the data dimension to one by the distance between the sample and central point of the data set and then by comparing it with a threshold. To calculate this distance, the location and scatter matrixes are used instead of the mean and variance-covariance matrixes in the robust estimators. Therefore, to maintain the robustness of distance, these estimators apply the optimal subset rather than the entire data matrix. This paper introduces four robust estimators namely the MVE, MCD, S and SD. Then these estimators are used to determine outlier data of 146 regional stream sediment samples of Shah Soliman Ali at South Khorasan province and also to analyze 18 elements. The results show that the Mahalanobis distance classical methods display 7 samples and robust estimators MVE, MCD, S and SD introduce 23, 35 ,20 and 34 samples as outliers, respectively. The principal component analysis in Q mode also show that the outlier samples with negative loads and the other samples with approximately positive loads show themselves in the second and the third components, respectively. It is also possible to separate outlier data from the rest in the scatter plot of the loads of PC 2 vs the loads of PC 3. The use of the location and scatter matrixes done by robust estimators is another important application of these estimators in multivariate statistics methods of exploration data analysis.Introduction: Human errors and changing nature of exploration data distribution are two main reasons in the creation of Outliers. The first step in the processing of the exploration data will be Identification and then modification of them. Existence of outliers is also caused the bias in the mean matrix and inflation in the variance-covariance matrix. So in this paper, we propose the use of robust estimators as one of the solutions and their performance is also evaluated.Methodology and Approaches: Results of the analysis of 18 elements to 146 stream sediments samples is used at the exploration region of Shad Soliman Ali as a data set. Four robust estimators such as MVE, MCD, S and SD have been also used to identify outlier data. And finally the results of the four estimator has been evaluated and compared with each other by PCA in Q mode.Results and Conclusions: From 146 samples, the MVE, MCD, S and SD robust estimators detected 23, 35, 20 and 34 as outlier data, respectively. Outlier samples also show up themselves with the negative loads on the PC2 and other samples with positive loads on the PC1. The population of the Outlier samples and the population of another samples are separated in the scatter plot of the PC2 loads vs the PC3 loads. So depending on the number of samples, one of these estimators can be used to identify outlier data.

Summary: One of the important problems in designing underground structures is geometrical and mechanical parameters of joint sets. Therefore designing underground structures should be done according to the structural conditions of the rock mass. In this regard, it is important to consider joint condition and spatial position of joints toward the underground excavation. In this study, using UDEC software, the structural stability of a tunnel with a horseshoe cross section in an intersecting jointed rock mass is investigated. Rock mass was containing two joint sets with different joint spacing. In the numerical models, joint shear stiffness, joint dip, joint opening, joint spacing, the ratio of joint spacing to width tunnel (l/b) and in situ stress were considered as variables. The area of failure zone was calculated separately by changing abovementioned parameters and the best condition concerning the least failure zone was determined. According to results, the largest failure area will created when dip difference between joint sets is lower than 40 degree, and further increasing of dip difference between joint sets causes reduction of area of failure zone. Also, increasing the ratio of joint spacing to tunnel width, leading to increase of the area of failure zone and consequently increase of instabilities. Instability exist in the range of this ratio from 0.11 to 0.33, and increasing of the ratio more than 0.33 provides improvement of stability condition (i.e., instability approaches zero) due to increasing block size and impossibility of block caving. The safest situation regarding minimum and maximum area of failure zone will occur for l/b=0.11 and 0.33, respectively.Introduction: In this research, the effective parameters of jointed rock mass, which affect the tunnel stability and the extent of the failure zone, were examined. The final shape of failure zone has presented in a table. Also the safest situation of intersecting joints has introduced.Methodology and Approaches: UDEC software has the ability of modeling jointed rock masses by considering the characteristics of joints. Therefore, using this software, the extent of the failure zone were calculated.Results and Conclusions: In this research, the area and the shape of failure zone of a jointed-rock are analyzed and the effect of main parameters on tunnel stability are discussed.

Summary: An excavation operation for the building purposes is a high-risk activity, which is done for different reasons, such as achieving an appropriate level of the earth for foundation or construction of basements. In this paper, using the Slide 6.0 program the stability of a pit wall in the outskirts of Qaen is investigated at first and then the pit wall stability after using soil nailing with various patterns is analyzed. Using back analysis, sensitivity analysis, and probabilistic analysis, this study presents a comprehensive model for analyzing pit walls, and will be useful for excavation operation in neighboring areas as well. Finally, several pit designs with acceptable safety factors have been proposed for pit excavation. Introduction: Due to the growing trend of urban populations, the construction activities are increasing in central and marginal areas of cities. One of the basic concerns in these constructions is the stability of the excavated pit wall. The basic rule of judgment about the stability of a pit wall is the standard safety factor. In the traditional deterministic approach of safety factor calculation, any error or uncertainty in the soil parameters is directly reflected in the results. In recent years, the use of the probabilistic approach that provides additional measures related to the probability of failure and risk rate has become popular. In the probabilistic approach in addition to the mean safety factor, the probability of failure and reliability index are also obtained. Methodology and Approaches: To perform a probabilistic analysis of a pit wall, strength properties of the soil layer and the soil density were defined as variable inputs. The coefficients of variation of these parameters according to laboratory experiments were selected. Normal and log-normal statistical distributions were used for the input variable parameters as recommended by USACE. For the efficient performance of the probabilistic analysis, Monte Carlo simulation was used. This way, and using the Slide 6.0 program, the stability of a pit wall in the outskirts of Qaen is investigated with various patterns of soil nailing as the supporting system. Results and Conclusions: According to the results of this study, the soil is unstable for excavation operation and employing soil nailing technique and reducing the pit wall slope angle are appropriate steps to achieve a secure condition. Several safe pit designs have been proposed for excavating the pit.

Summary: Tabriz metro twin tunnels in some stations are under ground water level. In addition to the loads from the weight of overburden, the load caused by pore water pressure is applied to them. To enter the current load into model certain boundary conditions must be considered that in this study, the probability of liquefaction and the impact of the earthquake on pore pressure loading structure have been investigated. Introduction: Geo-technical design of structures is encountered with a variety of different natural conditions (earthquake, liquefaction, etc.). This will be due to the complexity of behaviors and conditions. These structures during his lifetime, because dealing with different situations such as earthquake will not have fixed characteristics and behavior. Complex Mechanical behavior of the soil under statistical loads can be different and more complicated under dynamic loads. In this respect, the modeling of alternative behavior of saturated soil, especially in the interaction zone of soil – structure, has gained increasing research interest over past decades. Because the estimation of structure response in the soil liquefaction depends on pore water pressure, softening strain and decreasing of soil resistance. For correct investigating, linear dynamic analyze in effective stress is necessary. For this type of analyze couple or semi couple methods could be applied. In this regard Finn & Martin and Byrne could be regarded as semi couple models. Methodology and Approaches: From aforementioned semi couple models, Byrne model was chosen in this research. After calculation of related indexes, the model implemented in Flac2D software. The possibility of liquefaction take place in structure foundation was investigated by local tests results in effective stress method. For numerical modeling, the Bam earthquake acceleration was selected in DBE level among the existing acceleration and impact of earthquake dynamic load of on project structure pore pressure was investigated. Results and Conclusions: Using available data at the project structure the probability of liquefaction in the project region was investigated by cyclic stress method. It was estimated that with safety factor of 1.28 for Bam earthquake magnitude earthquake 6.5M, liquefaction will not occur. Nevertheless, due to exist of pore pressure at structure needed parameters was calculated in Byrne model to study simultaneous impact of dynamic loads and pore pressure to be used in numerical modeling. The results showed an increase in pore pressure due to dynamic loads caused by earthquakes so higher load values to the desired location (subway tunnel) is inserted and finally more effective maintenance system for the tunnel is estimated.