Parametric study of factors affecting fluid flow through a fracture     

Kunwar Mrityunjai Sharma  Debanjan Guha Roy  Praksh Kumar Singh  Lakshmi Kant Sharma  Trilok Nath Singh 《Arabian Journal of Geosciences》2017,10(16):362

Understanding the flow behavior through fractures is critically important in a wide variety of applications. In many situations, the fluid flow can be highly irregular and non-linear in nature. Numerical simulation can be employed to simulate such conditions which are difficult to replicate in laboratory experiments. Therefore, a parametric study has been conducted on the fluid flow through micro-fracture over a large range of inlet pressure, fluid density, fluid viscosity, temperature, joint roughness coefficient (JRC), and fracture using finite element analysis. Irregular fracture profiles were created using Barton’s joint roughness coefficient. The Navier-Stokes (NS) equation was used to simulate the flow of water in those micro-fractures. The result showed that the fracture, fluid, and ambient conditions have a wide and varied effect on the fluid flow behavior. The interrelationship between these parameters was also studied. The model simulation provided result in the form of velocity and pressure drop profile, which can be used to determine the behavior of flow under different condition. The volumetric flow was calculated for each condition and has been plotted against the corresponding parameter to study the interrelationship.  相似文献   

Mineralogy,petrography and micro-chemical characteristics of enclaves of mylonitic BIFs within Sukinda ultramafic complex,Odisha     

P. Sharma  B. K. Mohapatra  P. K. Nayak  S. Mishra  P. P. Singh 《Journal of the Geological Society of India》2017,89(5):541-546

Elongated NE-SW trending bodies of iron-rich rock are exposed adjacent to pyroxenite dyke within Sukinda ultramafic complex, Odisha. Field study followed by optical and electron microscopy, XRD and EPMA investigation reveal the rocks to be fine grained, weathered, limonitised; containing quartz, magnetite, hematite/martite and goethite. The rock has suffered from deformation during intrusion of chromiferous magma. It rarely shows banding/lamination, but largely exhibits mylonitic fabric, resulting from magmatic intrusion. The stronger deformation is evident from sub-grain formation, deformed mineral grains; often with orientation, stretching (boudinage) and shortening (folding); presence of porphyroclasts, pull-apart structure, undulose extinction, dynamic recrystallisation etc. From the microstructure and mineral abundance, the rock is designated as “Mylonitic Magentite Quartzite” (MMQ).Enrichment of some elements like Ni, Mg, Cr in the magnetite phase of MMQ is attributed to solid state diffusion of these elements from chromiferous mafic magma during thermal metamorphism. This is determined from electron probe microanalysis of iron-rich phase in MMQ, which is found to contain 88-90 wt% of FeO^(t) with ~1%, NiO, ~1%, MgO and 0.1% Cr₂O₃ having around 3 mole% of trevorite; 4-6% of magnesioferrite; 0.15-0.3% of chromite; 86-87% of magnetite and 3-4% of wustite. Considering presence of wustite as temperature indicator, the temperature of magma envisaged to be around 950-1100°C.In a later period, the MMQ has undergone oxidation and lateritisation owing to its prolonged exposure. During this process, new minerals like hematite and goethite substituted magnetite, resulting leaching of iron (FeO: 62-68%) and magnesium (MgO: 0.1-0.35) and enrichment of chromium (Cr₂O₃:4-7%) and nickel (NiO: 1.6-2.3%). The silica (SiO₂: 4-5%), alumina (Al₂O₃:~1%) are contributed by kaolinite, formed during lateritisation.The field and laboratory studies confirm these iron-rich exposures to be enclaves of BIFs, banded magnetite quartzite (BMQ) in particular, within the Sukinda chromiferous ultramafic complex. Micro-structural features and microchemical composition of iron minerals in these exposures are interpreted as the influence of forceful ultramafic intrusion into the existing BMQ and effect of thermal metamorphism followed by oxidation, weathering/lateritisation.  相似文献   

Stability investigation of hill cut soil slopes along National highway 222 at Malshej Ghat,Maharashtra   总被引：2，自引：0，他引：2  

L. K. Sharma  Ravi Kumar Umrao  Rajesh Singh  M. Ahmad  T. N. Singh 《Journal of the Geological Society of India》2017,89(2):165-174

The section of about 12 km of National highway 222 passing through the Malshej Ghat experience frequent slope failure due to complex geological condition, heavy rainfall and slope geometry. The area is part of Western Ghat Deccan trap and slope masses are made of basalt and its weathered crust (debris/soil). The soil slope failure problem mainly occur in rainy seasons due to induced pore water pressure and reduced strength of the slope mass. The present study has been carried out to investigate the slope forming material and assess the stability of soil slopes by numerical approach. For the identification of the vulnerable zones, field study has been carried out and five vulnerable soil slopes identified namely MGS1, MGS2, MGS3, MGS4 and MGS5 on the basis of degree of weathering and slope geometry. The laboratory experiments were carried out to determine the strength properties of the geomaterials. All the input variables acquired from the field and laboratory experiments have been used for numerical simulation, which was performed with the help of limit equilibrium method (LEM) and finite element method (FEM). Numerical analysis provides understanding of the slope behaviour and illustrates that MGS1 and MGS3 are stable slopes, MGS2 and MGS4 are critically stable, whereas, slope MGS5 is unstable. This study recommend the protection of soil slopes and suggest that more detailed investigation is required for long term remedial measures to prevent risk of damage in Malshej Ghat.  相似文献   

Assessment of Durability and Weathering State of Some Igneous and Metamorphic Rocks Using Micropetrographic Index and Rock Durability Indicators: A Case Study     

M. Ahmad  M. K. Ansari  Rajesh Singh  L. K. Sharma  T. N. Singh 《Geotechnical and Geological Engineering》2017,35(2):827-842

Weathering and durability are the key factors of the rock in the suitability and usefulness of different construction materials, building materials and engineering structures. A single test never predicts the entire factor for suitability of rock stone and aggregate in different uses. Thus, variety of physical, mechanical and chemical tests and indices of rocks are widely used to estimate and evaluate the rocks for the suitability of the required purpose. In all the cases, knowledge of durability and weathering properties are the most important along with the strength of the rock. Micropetrographic index and rock durability indicators (dynamic and static) are the one of the best methods to evaluate the rock for weathering and durability. To estimate these indices, variety of tests are performed such as petrographic examination test, point load index, sulfate soundness test, water absorption test, modified aggregate impact value test and test for specific gravity. Slake durability index and impact strength index tests were also performed for correlation with static and dynamic rock durability indicators due to its application and usefulness in the durability and strength of the rock materials. Micropetrographic index was obtained by petrographic examination test and correlated with all the physical and mechanical properties used for find out the durability indicators. The present study is to express the usefulness of these three indices in the classification of weathering and durability classes and estimation of durability indices by slake durability index, impact strength index and micropetrographic index.  相似文献   

Propagation of harmonic plane waves in a general anisotropic porous solid     

M. D. Sharma 《Geophysical Journal International》2008,172(3):982-994

Wave propagation is studied in a general anisotropic poroelastic solid. The presence of dissipation due to fluid-viscosity as well as hydraulic anisotropy of pore permeability are also considered. Biot's theory is used to derive a system of modified Christoffel equations for the propagation of plane harmonic waves in porous media. A non-trivial solution of this system is ensured by a determinantal equation. This equation is separated into two different polynomial equations. One is the quartic equation whose roots represent the complex velocities of four attenuating waves in the medium. The other is a eighth-degree polynomial whose roots represent the vertical slowness values for the four waves propagating upward and downward in a finite porous medium. Procedure is explained to associate the numerically obtained roots with the waves propagating in the medium. The slowness surfaces of waves reflected at the boundary of the medium are computed for a realistic numerical model. The behaviours of phase velocity surfaces are analysed with the help of numerical examples.  相似文献   

Thermal-convective instability of a composite plasma in a stellar atmosphere with Hall currents     

K. C. Sharma 《Astrophysics and Space Science》1986,125(2):299-304

The problem of thermal-convective instability of a hydromagnetic composite plasma in a stellar atmosphere has been studied with Hall effects. The criterion for monotonic instability has been found to be unchanged by the presence of Hall effects.  相似文献   

Thermal-convective instability of a composite rotating stellar atmosphere in the presence of a variable magnetic field,medium permeability and solute gradient     

R. C. Sharma  Anup Rajput 《Astrophysics and Space Science》1992,198(1):21-28

The thermal-convective instability of a composite rotating stellar atmosphere in the presence of a variable horizontal magnetic field is considered to include, separately, the effects of medium permeability and solute gradient. The criteria for monotonic instability in each case have been obtained which generalize the Defouw's criterion derived for thermal-convective instability in the absence of above effects.  相似文献   

List of forthcoming papers     

K. C. Sharma  Urvashi Gupta  R. C. Sharma 《Astrophysics and Space Science》1991,182(1):169-169

List of forthcoming papers  相似文献   

Thermosolutal-convective instability of a composite stellar atmosphere in the presence of a variable magnetic field     

R. C. Sharma  Veena Kumari 《Astrophysics and Space Science》1991,184(1):43-48

The thermosolutal-convective instability of a composite stellar atmosphere is considered in the presence of variable horizontal magnetic field and collisional effects. The criteria for monotonic instability are obtained which generalize the criterion derived for thermal-convective instability in the absence of above effects.  相似文献   

Gravitational instability of a composite and rotating plasma in the presence of a variable magnetic field through a porous medium     

R. C. Sharma  A. Rajput 《Astrophysics and Space Science》1992,187(1):105-111

The gravitational instability of an infinite homogeneous self-gravitating plasma through porous medium is considered to include, separately, the effects due to rotation and collisions between ionized and neutral components. The dispersion relations are obtained in both cases. It is found that the gravitational instability of a composite and rotating plasma in the presence of a variable horizontal magnetic field through porous medium is determined by the Jeans's criterion.  相似文献