On generalization of constitutive models from two dimensions to three dimensions     

N. Khalili  M. D. Liu 《国际地质力学数值与分析法杂志》2008,32(17):2045-2065

In this paper, a study is made of the generalization of constitutive models for geomaterials from two‐dimensional stress and strain states to three‐dimensional stress and strain states. Existing methods of model generalization are reviewed and their deficiencies are highlighted. A new method is proposed based on geometries of the model imprints on two normal planes. Using the proposed method, various three‐dimensional failure criterions suitable for geomaterials are implemented directly into a two‐dimensional model and the generalized model is identical to its original form for the axially symmetric condition. To demonstrate the application of the proposed method, the Modified Cam Clay model is extended using the Matsuoka–Nakai failure criterion. Simulations of soil behaviour for loading in the principal stress space are presented and analysed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Thermal recovery from a fractured medium in local thermal non‐equilibrium     

Rachel Gelet  Benjamin Loret  Nasser Khalili 《国际地质力学数值与分析法杂志》2013,37(15):2471-2501

Thermal recovery from a hot dry rock (HDR) reservoir viewed as a deformable fractured medium is investigated with a focus on the assumption of local thermal non‐equilibrium (LTNE). Hydraulic diffusion, thermal diffusion, forced convection and deformation are considered in a two‐phase framework, the solid phase being made by impermeable solid blocks separated by saturated fractures. The finite element approximation of the constitutive and field equations is formulated and applied to obtain the response of a generic HDR reservoir to circulation tests. A change of time profile of the outlet fluid temperature is observed as the fracture spacing increases, switching from a single‐step pattern to a double‐step pattern, a feature which is viewed as characteristic of established LTNE. A dimensionless number is proposed to delineate between local thermal equilibrium (LTE) and non‐equilibrium. This number embodies local physical properties of the mixture, elements of the geometry of the reservoir and the production flow rate. All the above properties being fixed, the resulting fracture spacing threshold between LTNE and LTE is found to decrease with increasing porosity or fluid velocity. The thermally induced effective stress is tensile near the injection well, illustrating the thermal contraction of the rock, while the pressure contribution of the fracture fluid is negligible during the late period. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

A new approach for the geological risk evaluation of coal resources through a geostatistical simulation   总被引：1，自引：1，他引：0  

Omid Ashgari  Nasser Madani Esfahani 《Arabian Journal of Geosciences》2013,6(3):929-943

Estimations of mineral resources and ore reserves have been recently widely used by mining engineers and investors. The classification framework based on the prepared code by the Joint Ore Reserves Committee of The Australasian Institute of Mining and Metallurgy, Australian Institute of Geoscientists and Minerals Council of Australia (JORC code), which is one of the international standards for mineral resource and ore reserve reporting, provides a template system that conforms to international society requirements. Recent research has shown that an existing fault risk can affect the mineral resource and ore reserve estimation. According to this research, the faulted area that is involved in the effect on the estimated region is so extensive that it is not distinguishable. In this research, a new method called FGT (F for fault, G for grade and T for thickness) is introduced and presented for the estimation of mineral resources. The proposed method can provide an error map of a particular aspect of the combination of coal accumulation (G), fault risk (F) and thickness (T), and its output would categorise the mineral resources. This method was implemented in the Parvadeh Ш coal deposit, which is located in the eastern portion of Central Iran. The deposit contains five seams named B1, B2, C1, C2 and D; of these, C1 was selected as the most important seam in the exploratory grid analysis. Thus, C1 alone can reflect the properties of the Parvadeh Ш deposit. In this study, we compared the conventional method and the FGT method. This comparison indicated that the areas that should be rejected from the region in the FGT method are less and more distinguishable than those determined with the conventional method. Therefore, the inferred resources can be completely differentiated from the indicated and measured resources with a high resolution. The conventional method cannot distinguish between these three categories at this level of resolution. Therefore, the FGT approach has high precision in classifying the coal resource compared to the conventional method.  相似文献   

Fault detection in 3D by sequential Gaussian simulation of Rock Quality Designation (RQD)   总被引：1，自引：0，他引：1  

Nasser Madani Esfahani  Omid Asghari 《Arabian Journal of Geosciences》2013,6(10):3737-3747

Gazestan phosphate ore deposit (Central Iran) is an apatite deposit which is instrumental in selecting the method of excavation. The position of fault systems and the condition of rock quality also play a role in the method used for mineral resources and ore reserves estimation. Conversely, the Rock Quality Designation (RQD) is a parameter that provides a quantitative judgment of rock mass quality obtained from drill cores. This factor can be applied to detect the fractured zones which occur due to fault systems. Additionally, the faulted areas can be determined by surface geological map and a few by core drilling. Some of the faulted areas are not distinguishable in the surface and are covered by soils, especially within 3D modeling and visualization. In this study, an attempt has been made to establish a relationship between the RQD percentages which were geostatistically simulated and faulted areas through the region. In comparison, the results showed that low RQD domains (RQD <20 %) can be interpreted as fault zones; high RQD domains (RQD >50 %) correspond to less fractured areas, and the contact between high and low RQD domain is gradual. Therefore, this categorization of RQD domains can be incorporated to detect the faulted zones in 3D models for mine design. Based on the categorization, the uncertainty within the area was calculated to introduce two new core drilling points for the completion of this phase of exploratory grid from the fault structural viewpoint, in order to have a proper model of ore reserve to estimate. It was concluded that this procedure can be utilized for conceptual comprehension of fault trends in 3D modeling for the method selection of excavation and complete the estimation procedure phase.  相似文献   

Focal mechanism of Badr earthquake, Saudia Arabia of August 27, 2009     

Khalid S. Aldamegh  Hesham Hussein Moussa  S. Nasser Al-Arifi  Sayed S. R. Moustafa  Moustafa Hemeda Moustafa 《Arabian Journal of Geosciences》2012,5(4):599-606

Focal mechanism solution of the 27th August 2009 earthquake (mb?=?4.0) that occurred in the Badr area, northwest of Saudi Arabia, approximately 50?km from the Red Sea has been determined from the P-wave first motion polarities. Results show normal faulting mechanism with a negligible component of strike-slip motion with NE T-axis direction. This type of mechanism is common with other earthquakes of the northwestern Saudi Arabia and is considered to present the tectonic movement of the region. The dominantly extensional tectonic regime in this province demonstrates the influence of NE extension in the Red Sea. The strikes of the solution are consistent with those of the main faults near the epicenter. Hypocentral location of this earthquake was carried out using the data from the King Abdulaziz City of Science and Technology Seismic Network, Saudi Arabia, and the Egyptian National Seismological Network, Egypt. The horizontal and vertical confidence estimates are 0.5?km for both. The local magnitude, M _L, following the Richter??s original definition was also derived from ten digital three-component broadband seismograms. The average local magnitude determined in this study is 3.8?±?0.17. The estimated seismic moment of this event is $ {3}.{\hbox{7e}} + {14}\,{\hbox{Nm}}\left( {{M_{\rm{W}}} = {3}.{66}\pm 0.0{7}} \right) $ .  相似文献   

Dynamic equations for steady spatially varied open channel flow: a critical review     

P. Venkataraman  M.S. Nasser  A.S. Ramamurthy 《Advances in water resources》1982,5(2):66-72

A review of the dynamic equations governing steady spatially varied flow in open channels is presented. These equations are derived by employing either the momentum or the energy principle: the choice of the method employed is based on convenience. Nevertheless, the two approaches yield different results when applied to a particular flow situation. Recent researches have established that this anamoly is due to the omission of the influence of the lateral flow. The inconsistencies existing among the different forms of these equations and the rather incomplete nature of their derivation are discussed. It is believed that with the present state of knowledge, it is possible to obtain identical spatially varied flow profiles when the influencing parameters are properly evaluated whether one uses the momentum or the energy approach. The need for further study to provide a better understanding of this practically important phenomenen is established and potential research directions are defined. Recent contributions to the analysis of the hydraulic characteristics of the spatially varied flow phenomenon and the delineation of the spatially varied flow profiles into eight possible patterns are also presented.  相似文献   

Spatiotemporal shoreline change in Boushehr Province coasts,Iran     

Zeinali  Saeed  Talebbeydokhti  Nasser  Dehghani  Maryam 《中国海洋湖沼学报》2020,38(3):707-721

Journal of Oceanology and Limnology - Since coastal areas have highly dynamic nature and are one of the most beneficial regions of civilizations, it is of great significance to understand their...  相似文献   

Mineralogical and geochemical investigation of some pegmatites from the Mashad area,northeastern Iran     

.Dr. H. Khalili 《Mineralogy and Petrology》1977,24(3):151-160

Summary Pegmatitic dikes and masses of various sizes occur in a granite intrusion in the Mashad area, northeastern Iran. Their geochemistry, as well as that of the parent granite was investigated using some 40 specimens. Major constituents and trace elements were determined by means of X-ray fluorescence and spectrographic methods. Anomalously high concentrations of Be and Nb and indications of their minerals beryl and columbite were observed. Therefore, the pegmatites of this area may prove to be a potential source for Be, Nb, Ta and possibly Li.

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Mineralogische und geochemische Untersuchung einiger Pegmatite aus der Gegend von Mashad, Nordost-Iran

Zusammenfassung In einer Granitintrusion in der Gegend von Mashad, Nordost-Iran, kommen pegmatitische Gänge und Massen verschiedener Größe vor. Unter Verwendung von etwa 40 Proben wurde ihre Geochemie und die ihres Muttergranites untersucht. Die Hauptbestandteile und Spurenelemente wurden mit Röntgenfluoreszenz und spektrographischen Methoden bestimmt. Außergewöhnlich hohe Konzentrationen an Be und Nb und Hinweise auf ihre Minerale Beryll und Columbit wurden beobachtet. Die Pegmatite dieser Gegend könnten sich folglich als potentielle Lieferanten für Be, Nb, Ta und möglicherweise Li herausstellen.

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With 1 Figure  相似文献   

Development of stochastic dynamic Nash game model for reservoir operation. I. The symmetric stochastic model with perfect information     

Arman Ganji  Davar Khalili  Mohammad Karamouz 《Advances in water resources》2007

Increasing water demands, higher standards of living, depletion of resources of acceptable quality and excessive water pollution due to agricultural and industrial expansions have caused intense social and political predicaments, and conflicting issues among water consumers. The available techniques commonly used in reservoir optimization/operation do not consider interaction, behavior and preferences of water users, reservoir operator and their associated modeling procedures, within the stochastic modeling framework. In this paper, game theory is used to present the associated conflicts among different consumers due to limited water. Considering the game theory fundamentals, the Stochastic Dynamic Nash Game with perfect information (PSDNG) model is developed, which assumes that the decision maker has sufficient (perfect) information regarding the associated randomness of reservoir operation parameters. The simulated annealing approach (SA) is applied as a part of the proposed stochastic framework, which makes the PSDNG solution conceivable. As a case study, the proposed model is applied to the Zayandeh-Rud river basin in Iran with conflicting demands. The results are compared with alternative reservoir operation models, i.e., Bayesian stochastic dynamic programming (BSDP), sequential genetic algorithm (SGA) and classical dynamic programming regression (DPR). Results show that the proposed model has the ability to generate reservoir operating policies, considering interactions of water users, reservoir operator and their preferences.  相似文献   

Stability of buoyancy opposed mixed convection in a vertical channel and its dependence on permeability     

P. Bera  A. Khalili 《Advances in water resources》2007

Non-Darcy mixed convective flow of water due to external pressure gradient and buoyancy opposed forces are considered in a vertical channel filled with porous medium, which can be either isotropic or anisotropic. The linear theory of stability analysis has been used to numerically investigate the dependence of the transition behavior of the fully developed basic flow on the permeability of the medium. Numerical experiments indicate that mainly two main instability modes appear: Rayleigh–Taylor (R–T) and buoyant instability. For Darcy numbers (Da) ?10⁻⁹, R–T instability dominates within the entire Reynolds number (Re) range considered here. It was also found that for the same Re, the fully developed base flow is highly unstable (stable) for porous media with high (low) permeability. Further, it was seen that the disturbance isotherm cells migrate from the channel walls toward the centerline when permeability is reduced. Reducing the permeability by one order of magnitude (corresponding to a decrease of Darcy number from 10⁻⁶ to 10⁻⁷) increases base flow stability approximately 20-fold. For higher Reynolds numbers, buoyant, mixed and shear instability of the basic flow were found when Da was increased from 10⁻⁷ to 10⁻³. However, for cases in which permeability and porosity behaved as suggested by Carman–Kozeny relation (CKR), buoyant stability was the only mode of instability. Critical values of the Rayleigh (Ra) and Darcy (Da) numbers in the R–T mode of instability were related to each other by the hyperbolic function RaDa = −2.465.  相似文献