Quasi-static deformation due to two-dimensional seismic sources embedded in an elastic half-space in welded contact with a poroelastic half-space     

Sunita Rani  Sarva Jit Singh 《Journal of Earth System Science》2007,116(2):99-111

The Biot linearized theory of fluid saturated porous materials is used to study the plane strain deformation of a two-phase medium consisting of a homogeneous, isotropic, poroelastic half-space in welded contact with a homogeneous, isotropic, perfectly elastic half-space caused by a two-dimensional source in the elastic half-space. The integral expressions for the displacements and stresses in the two half-spaces in welded contact are obtained from the corresponding expressions for an unbounded elastic medium by applying suitable boundary conditions at the interface. The case of a long dip-slip fault is discussed in detail. The integrals for this source are solved analytically for two limiting cases: (i) undrained conditions in the high frequency limit, and (ii) steady state drained conditions as the frequency approaches zero. It has been verified that the solution for the drained case (ω → 0) coincides with the known elastic solution. The drained and undrained displacements and stresses are compared graphically. Diffusion of the pore pressure with time is also studied.  相似文献   

Weathering and landslide occurrences in parts of Western Ghats,Kerala   总被引：2，自引：0，他引：2  

K. S. Sajinkumar  S. Anbazhagan  A. P. Pradeepkumar  V. R. Rani 《Journal of the Geological Society of India》2011,78(3):249-257

The climatic condition of Western Ghats has influenced the process of weathering and landslides in this mountainous tract along the southwest coast of India. During the monsoon period, landslides are a common in the Western Ghats, and its intensity depends upon the thickness of the loose unconsolidated soil formed by the process of weathering. Debris landslides with a combination of saprock, saprolite and soil, indicate the role of weathering in landslide occurrences. This paper reports on how the weathering in the windward slope of Western Ghats influences the occurrence of landslides and the factors which accelerate the weathering process. Rock and soil samples were collected from the weathering profile of hornblende gniess and granite gneiss. The chemical analysis and the calculated Chemical Index of Alteration (CIA) indicate the significant weathering and its possible influence on landslide occurrences in the study area. Mainly, the CIA value of lateritic soil and forest loam indicated the extent of high chemical weathering in this region. Rainfall is the dominant parameter influencing the chemical weathering process. In addition, deforestation, land use practices and soil erosion are some of the other important factors accelerating the weathering process and landslide occurrences in the region. The locations of the previous landslides superimposed on geology and soil show that most of the landslide occurrences are associated with the highly weathered zone, particularly lateritic soil and the ‘severe’ (rock outcrop) erodability zone.  相似文献   

Stability assessment and characterization of colloids in coastal groundwater aquifer system at Kalpakkam   总被引：1，自引：0，他引：1  

R. Deepthi Rani  P. Sasidhar 《Environmental Earth Sciences》2011,62(2):233-243

Natural colloids have a potential role in facilitating the transport of radionuclides in groundwater. To assess the role of mobile colloidal phases in radionuclide transport, characterization of colloids for size, size distribution, zeta potential, surface charge and elemental composition is required. Groundwater samples were collected from 12 borewells in the study area and were characterized with respect to physicochemical parameters. Water quality parameters such as pH, temperature, specific conductance, TDS and dissolved O₂ were measured in situ. Based on salinity, two groundwater types were identified in the study area: (1) freshwater type and (2) brackish type. Laboratory and field-scale turbidity measurements in addition to quantitative analysis of major ions were carried out. It was observed that the colloid concentrations are reduced at higher salinity. Zetasizer, particle size analyzer, scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction techniques were used to characterize the colloidal particles in groundwater. Colloids were present in all the groundwater samples, the concentration varying between 0.05 and 6 mg/L. Colloid concentration was greater in wells with low ionic strength and the number of colloidal particles varied between 3 × 10⁹ and 4 × 10¹¹ particles/L. The average colloid size varied between 200 and 350 nm for various samples. The zeta potential of the colloidal particles varied between −25.5 and –34.0 mV. SEM analysis of colloidal particles revealed the presence of clays particularly kaolinite and that the mineral composition of colloids reflects the mineralogy of the aquifer. For proper risk assessment and remediation studies, the role of colloids in radionuclide transport assumes greater importance. This study highlights the need for, and relevance of, detailed colloid characterization to assess its role in the migration of radionuclides from near surface disposal facilities.  相似文献   

The copper and zinc abundances in stars of galactic sub-structures     

T. V. Mishenina  T. I. Gorbaneva  N. Yu. Basak  C. Soubiran  V. V. Kovtyukh 《Astronomy Reports》2011,55(8):689-703

We have determined abundances of copper, zinc, sodium, and aluminum in the atmospheres of 172 F, G, and K dwarf stars (−1.0 < [Fe/H] < 0.3) belonging to the Galaxy’s thin and thick disks and to the Hercules moving group. Our observations were performed with the ELODIE échelle spectrometer on the 1.93-m telescope of the Haute Provence Observatory, with a resolving power of R = 42 000 and signal-to-noise ratio S/N > 100. The Na, Al, Cu, and Zn abundances were derived in an LTE approximation; the synthetic spectrum for the copper lines was calculated taking into account super-fine structure of the lines. We analyzed the abundances of these elements as a function of metallicity [Fe/H] for stars of the thin and thick disks of the Galaxy and the Hercules moving group. The Cu abundances and their trends with metallicity are essentially the same in the three studied sub-structures. The mean Al and Zn abundances for stars of the thin and thick disks differ significantly.  相似文献   

Adiabatic radial pulsations of a composite stellar model     

Manmohan Singh  Sudha Rani Agarwal 《Astrophysics and Space Science》1983,94(2):351-359

Small adiabatic radial oscillations of composite models have been investigated. The effect of central condensation ρ_c√ρ on the period of pulsation have also been examined. In has been shown that the second moment of mass concentration characterize the periods of pulsation more effectively than central condensation.  相似文献   

Non-flat pilgrim dark energy FRW models in modified gravity     

Shamaila Rani  Abdul Jawad  Ines G. Salako  Nadeem Azhar 《Astrophysics and Space Science》2016,361(9):286

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A hydrochemical approach to estimate mountain front recharge in an aquifer system in Tamilnadu,India     

Banaja Rani Panda  S. Chidambaram  N. Ganesh  V. S. Adithya  M. V. Prasanna  K. Pradeep  U. Vasudevan 《中国地球化学学报》2018,37(3):465-488

Mountain-front recharge (MFR) is a process of recharging an aquifer by infiltration of surface flow from streams and adjacent basins in a mountain block and along a mountain front (MF). This is the first attempt in India to estimate MFR along the foothills of Courtallam using hydrogeochemistry and geostatistical tools. The estimation of MFR has been carried out by collecting groundwater samples along the foothills of Courtallam. Collected water samples were analyzed for major cations and anions using standard procedures. Hydrogeochemical facies show the existence of four water types in this region. Calcium-rich water derived from gneissic rock terrain indicates significant recharge from higher elevation. Log pCO₂ and ionic strength of the samples were also calculated to identify the geochemical process. Majority of the collected samples have sodium-rich water and weak ionic strength, which indicate foothill recharge and low residence time. Silicate and carbonate weathering have an equal interplay along the foothills with a relatively large fraction of Mg from the MF. The spatial diagrams of three factors show that the southern part of the study area is dominated by both weathering and anthropogenic processes, whereas the northern part is dominated by both leaching and weathering processes. Thus, the dominant weathering process represented by the second factor indicates the large recharge process along the foothills.  相似文献   

Carcinogenic and Non-carcinogenic Risk Assessment of Metals in Groundwater via Ingestion and Dermal Absorption Pathways for Children and Adults in Malwa Region of Punjab     

Vikas Duggal  Asha Rani 《Journal of the Geological Society of India》2018,92(2):187-194

The concentration of trace metals was measured in groundwater samples collected from Malwa region of Punjab, India. The samples were analyzed by using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The results were compared with permissible limits prescribed by various health and environmental protection agencies. The concentrations of trace metals such as Mn, Se, Mo, Cd, Sb and Pb were higher than their respective permissible limits at some sampling sites. The total hazard index (HI_total) (summing the hazard index through ingestion and dermal routes) at all the sampling sites exceeded or nearing unity, indicating the presence of non-carcinogenic health effects from ingestion of groundwater and dermal contact with groundwater. The results reveal that the total excess lifetime cancer risk (ELCR_total) of metals exposure was in accordance with the acceptable lifetime risks for carcinogens in drinking water.  相似文献   

Physico-chemical conditions of four calc-alkaline granitoid plutons of Chhotanagpur Gneissic Complex,eastern India: Tectonic implications     

B Goswami  P Roy  A Basak  S Das  C Bhattacharyya 《Journal of Earth System Science》2018,127(8):120

Petrography and mineralogy of four calc-alkaline granitoid plutons Agarpur, Sindurpur, Raghunathpur and Sarpahari located from west to east of northern Purulia of Chhotanagpur Gneissic Complex, eastern India, are investigated. The plutons, as a whole, are composed of varying proportions of Qtz–Pl–Kfs–Bt–Hbl±Px–Ttn–Mag–Ap–Zrn±Ep. The composition of biotite is consistent with those of calc-alkaline granitoids. Hornblende–plagioclase thermometry, aluminium-in-hornblende barometry and the assemblage sphene–magnetite–quartz were used to determine the P, T and \(f_{\mathrm{O}_2}\) during the crystallisation of the parent magmas in different plutons. The plutons are crystallised under varying pressures (6.2–2.4 kbar) and a wide range of temperatures (896–\(718{^{\circ }}\hbox {C}\)) from highly oxidised magmas (log \(f_{\mathrm{O}_2}\) \(-11.2\) to \(-15.4\) bar). The water content of the magma of different plutons varied from 5.0 to 6.5 wt%, consistent with the calc-alkaline nature of the magma. Calc-alkaline nature, high oxygen fugacity and high \(\hbox {H}_{2}\hbox {O}_{{\mathrm{melt}}}\) suggest that these plutons were emplaced in subduction zone environment. The depths of emplacement of these plutons seem to increase from west to east. Petrologic compositions of these granitoids continuously change from enderbite (opx-tonalite: Sarpahari) in the east to monzogranite (Raghunathpur) to syenogranite (Sindurpur) to alkali feldspar granite (Agarpur) in the west. The water contents of the parental magmas of different plutons also increase systematically from east to west. No substantial increase in the depth of emplacement is found in these plutons lying south and north of the major shear zone passing through the study area suggesting the strike-slip nature of the east–west shear zone.  相似文献   

Geochemical alterations in surface waters of Govind Ballabh Pant Sagar,Northern Coalfield,India     

Anshumali  Manisha Rani  Sanjay Kumar Yadav  Ashish Kumar 《Environmental Earth Sciences》2014,71(7):3181-3193

Major ions showed high concentrations, ionic strength and chemical activity in the surface waters of Govind Ballabh Pant Sagar reservoir. Various geochemical ratios showed the dominance of silicate over carbonate weathering and major ions such as Na⁺ + K⁺ account for about 52 % of the cation budget. The high Na⁺ and K⁺ showed sedimentation of rock/coal particles consisting of highly weathered silicate minerals contributed by the discharge of mine water, fly ash mixing during transportation, etc. Further, Ca²⁺ + Mg²⁺/Na⁺ + K⁺ ratio was <1 (0.92) indicating the occurrence of silicate weathering in the reservoir catchment. The comparative assessment showed that the proportion of Ca²⁺ + Mg²⁺/Na⁺ + K⁺ tends to be lower along the coal mining belts compared to non-coal mining regions in the world. The Ca²⁺/SO₄ ^2? ratio <1 revealed not only H₂CO₃ but H₂SO₄ also acting as a source of protons for rock weathering. The cause underlying these differences can be related directly to geological substrate and anthropogenic activities.  相似文献