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Modelling density driven flow problems requires an excessive computational time and/or heavy equipments due to the non-linear coupling between flow and transport equations. In this work, we develop a robust numerical model with efficient advanced approximations for both spatial and temporal discretizations in order to reduce the excessive computational requirement while maintaining accuracy. 相似文献
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Besser Houda Mokadem Naziha Redhouania Belgacem Rhimi Nacira Khlifi Faten Ayadi Yosra Omar Zohra Bouajila Abdelhakim Hamed Younes 《Arabian Journal of Geosciences》2017,10(16):1-18
Arabian Journal of Geosciences - The present work is concerned with the valorization of clay minerals of the Aleg formation (Coniacian-middle Campanian) in the clinker manufacturing. The studied... 相似文献
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Peyman Afzal Ahmad Khakzad Parviz Moarefvand N. Rashidnejad Omran Bijan Esfandiari Younes Fadakar Alghalandis 《Journal of Geochemical Exploration》2010,104(1-2):34-46
Geochemical anomaly separation using the concentration–area (C–A) method at Kahang (Gor Gor) porphyry system in Central Iran is studied in this work. Lithogeochemical data sets were used in this geochemical survey which was conducted for the exploration for Cu mineralization in dioritic and andesitic units at Kahang Cu–Mo porphyry system. Similar surveys were also carried out for Mo and Au exploration in these rock units. The obtained results have been interpreted using rather extensive set of information available for each mineralized area, consists of detailed geological mapping, structural interpretation and alteration data. Anomalous threshold values for the mineralized zone were computed and compared with the statistical methods based on the data obtained from chemical analysis of samples for the lithological units. Several anomalies at a local scale were identified for Cu (224 ppm), Mo (63 ppm), and Au (31 ppb), and the obtained results suggests existence of local Cu anomalies whose magnitude generally is above 1000 ppm. The correlation between these threshold values and ore grades is clearly interpreted in this investigation. Also, the log–log plots show existence of three stages of Cu enrichment, and two enrichment stages for Mo and Au. The third and most important mineralization event is responsible for the presence of Cu at grades above 1995 ppm. The identified anomalies in Kahang porphyry system, and distribution of the rock types, are mainly monzodiorite and andesitic units, do have special correlation with Cu and monzonitic and dioritic rocks, especially monzodioritic type, which is of considerable emphasis. The threshold values obtained for each element are always lower than their mean content in the rocks. The study shows threshold values for Cu is clearly above the mean rock content, being a consequence of the occurrence of anomalous accumulations of phyllic, argillic and propyllitic alterations within the monzonitic and dioritic rocks especially in monzodioritic type. The obtained results were compared with fault distribution patterns which reveal a positive direct correlation between mineralization in anomalous areas and the faults present in the mineralized system. 相似文献
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The Henry saltwater intrusion problem provides a semi-analytical solution that is largely used for benchmarking density-dependent groundwater flow models. The major drawback of this problem arises from the high dispersion value used by Henry (represented by the dimensionless parameter b?=?0.1). Finding a stable semi-analytical solution for small values of b is challenging due to the low convergence of the corresponding nonlinear system. In this work, an accurate semi-analytical solution is developed in the case of a very narrow transition zone corresponding to b?=?0.005. About 6,330 terms are used in the Fourier series to accurately represent the solution. The resolution of the corresponding highly nonlinear system is made possible by the modified Powell hybrid algorithm due to the analytical evaluation of the Jacobian, which drastically reduces the computational time. The new test problem is also investigated numerically using different numerical methods and different mesh sizes to show its high worthiness, compared to the standard Henry problem, for benchmarking density driven flow codes. 相似文献
25.
Delineation of mineralization zones in porphyry Cu deposits by fractal concentration–volume modeling
Peyman Afzal Younes Fadakar Alghalandis Ahmad Khakzad Parviz Moarefvand Nematolah Rashidnejad Omran 《Journal of Geochemical Exploration》2011
The purpose of this study was to identify the various mineralization zones especially supergene enrichment and hypogene in two different Iranian porphyry Cu deposits, based on subsurface data and by using the proposed concentration–volume (C–V) fractal method. The Sungun and Chah-Firuzeh porphyry Cu deposits, which are situated in NW and SE Iran, respectively, were selected for this study. Straight lines fitted through log–log plots showing C–V relations for Cu were employed to separate supergene enrichment and hypogene zones from oxidation zones and barren host rocks in the two deposits and to distinguish a skarn mineralized zone from the hypogene zone in Sungun deposit. In the proposed C–V fractal method, the identification of mineralization zones is based on power–law relationships between Cu concentrations and the volume of rocks hosting porphyry Cu mineralization. Separate subsurface data from the two deposits were analyzed by C–V fractal method and the results have been compared with geological models which included alteration and mineralogical models. The comparison shows that the interpreted zones based on the C–V fractal method are consistent with the geological models. The proposed C–V method is a new approach to defining zones in a mineral deposit and there was no commercial software available to perform the relevant calculations; therefore, a fractal concentration–volume (FCV) software was designed by the authors to achieve this goal. 相似文献
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Younes Hamed 《Arabian Journal of Geosciences》2013,6(3):697-710
Gafsa region is one of the most productive artesian basins in Southern Tunisia. It is located in the southwestern part of the country, and its groundwater resources are developed for water supply and irrigation. Proper understanding of the geochemical evolution of groundwater is important for sustainable development of water resources in this region. A hydrogeochemical survey was conducted on the Plio-Quaternary shallow and on the Complex Terminal aquifers system using major (Ca, Mg, Na, SO4, Cl, NO3 and HCO3) and minor (Sr) elements, in order to evaluate the groundwater chemistry patterns and the main mineralization processes occurring in this system. Hydrochemical and isotopic data were used in conjunction with hydrogeological characteristics to investigate the groundwater composition in these aquifers. It has been demonstrated that groundwaters acquire their mineralization principally by water–rock interaction, i.e. dissolution of evaporites (halite/gypsum, pyrite, etc.) and return flow of irrigation waters, and by anthropogenic activities due to the use of nitrogen (N) fertilizers–pesticides in agriculture. The isotopic study of “stable isotopes, radiocarbon and tritium” (Yermani 2002) shows that a paleoclimatic recharge is corroborated by the relatively low carbon-14 activities (5–25.3%) of the referred groundwater group samples, which were interpreted as recharge occurring during the late Pleistocene and the early Holocene periods. The water feedings of these aquifers are mainly provided by infiltration of precipitations, infiltration of irrigation water, lateral feeding from Cretaceous relieves from the South and the North and along recent and fossil drainage networks that constitute major freshwater sources in groundwater tables (Hamed et al., J Environ Protect 1:466–474, 2010a). 相似文献
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The uniaxial compressive strength (UCS) of rocks is a critical parameter required for most geotechnical projects. However, it is not always possible for direct determination of the parameter. Since determination of such a parameter in the lab is not always cost and time effective, the aim of this study is to assess and estimate the general correlation trend between the UCS and indirect tests or indexes used to estimate the value of UCS for some granitoid rocks in KwaZulu-Natal. These tests include the point load index test, Schmidt hammer rebound, P-wave velocity (Vp) and Brazilian tensile strength (σt). Furthermore, it aims to assess the reliability of empirical equations developed towards estimating the value of UCS and propose useful empirical equations to estimate the value of UCS for granitoid rocks. According to the current study, the variations in mineralogy, as well as the textural characteristics of granitoid rocks play an important role in influencing the strength of the rock. Simple regression analyses exhibit good results, with all regression coefficients R2 being greater than 0.80, the highest R2 of 0.92 being obtained from UCS versus σt. Comparison of equations produced in the current study as well as empirical equations derived by several researchers serves as a validation. Also illustrate that the reliability of such empirical equations are dependent on the rock type as well as the type of index tests employed, where variation in rock type and index tests produces different values of UCS. These equations provide a practical tool for estimating the value of UCS, and also gives further insight into the controlling factors of the strength of the granitoid rocks, where the strength of a rock is a multidimensional parameter. 相似文献
29.
The Henry semi-analytical solution is developed for stratified aquifers with exponential and Gaussian permeability–depth relationships and small dispersion. The semi-analytical solution is sought by expanding the stream function and the concentration in an infinite Fourier series truncated at given orders. Due to the heterogeneity, the semi-analytical solution contains additional terms and quickly becomes impractical because of the high truncation orders required to yield stable results. An appropriate evaluation of the most expensive term, involving fairly complex summations, is proposed to render the computation of the semi-analytical solution affordable. Three configurations with the same transmissivity as that for the homogeneous Henry problem are investigated. The first configuration considers an exponential decay of the permeability (k) with depth. The second and third configurations consider an exponential increase and a Gaussian high-low-high distribution of k with depth, respectively. The three configurations are also investigated numerically using an accurate numerical code based on the method of lines and advanced spatial discretization schemes. An excellent agreement is obtained between the semi-analytical and the numerical solutions for all test cases. The results show that the amount of saltwater intrusion is strongly dependent on the heterogeneity. Further, the heterogeneous Henry problem is found to be more suitable for benchmarking density-driven numerical codes because the numerical solution is more sensitive to the grid size than for the homogeneous problem. 相似文献
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Zerzour Oussama Gadri Larbi Hadji Riheb Mebrouk Faouzi Hamed Younes 《Geotechnical and Geological Engineering》2021,39(5):3337-3346
Geotechnical and Geological Engineering - Geostatistical techniques are usually practical in the development and production stages of mining projects. The Ouenza deposit is the main iron ore... 相似文献