One-Dimensional Consolidation of Sedimented Stowed Pond Ash     

Devi Prasad Mishra  Samir Kumar Das 《Geotechnical and Geological Engineering》2012,30(4):685-695

Use of fly ash locked in the ash ponds in geotechnical applications such as stowing or backfilling of the mines is an attractive alternative to solve the disposal problem. Before it is used as a stowing or backfilling material, the response of the fly ash?to imposed load must be determined in order to assess its load taking ability. The present study examines the effect of time and incremental load on the consolidation characteristics of the sedimented stowed pond ash using a fixed ring consolidometer. The important parameters, viz. rate of settlement, consolidation coefficients and void ratio, etc. of the hydraulically stowed pond ash collected after 7, 14, 21, 28 and 35?days of stowing under step incremental loads are determined. The study revealed that 60.42–84.87% settlement of the sedimented stowed pond ash takes place in the initial 1?min of the loading. In addition, it is observed that the coefficient of consolidation of the sedimented stowed pond ash, which varies in the range of 0.0195–0.1882?cm²/min, is comparatively low and decreases with the increment of applied load and time. This indicates that the structures lying above the stowed pond ash mass will undergo gradual settling and not suffer large deformation.  相似文献   

Earthquake hazards and community resilience in Baluchistan   总被引：5，自引：3，他引：2  

Syed Ainuddin  Jayant Kumar Routray 《Natural Hazards》2012,63(2):909-937

Resilience is widely used from a variety of research perspectives; however, community resilience in particular is applied to a number of natural hazards and disasters-related studies, programs, and activities. It is also acknowledged that its measurement is cumbersome but not impossible. The prime objective of this paper is to measure the community resilience of an earthquake-prone area in Baluchistan. The article presents the concept of resilience, its approaches, selection of indicators, formulation of subjective assessment method for weighting the indicators, and finally, developing the community resilience index. For the community resilience measurement, a survey was conducted among 200 households in two earthquake risk zones of Quetta city, using simple random sampling method. The overall composite community resilience index revealed that the resilience is low in both the zones??A and B. However, it is revealed that there is a significant difference between the zones when compared against the components and indicators. Community resilience components such as economic, institutional, and physical have received higher index values in Zone B as compared to Zone A. Based on the findings, it is recommended to improve the socioeconomic, institutional, and structural (housing) conditions of the community by raising the community awareness and preparedness, implementing building codes, and providing income-generating activities in order to enhance the community resilience to cope up with earthquake hazards in the future.  相似文献   

Bankline change and the facets of riverine hazards in the floodplain of Subansiri–Ranganadi Doab, Brahmaputra Valley, India     

Apurba Kumar Das  Rajesh Kumar Sah  Nabajit Hazarika 《Natural Hazards》2012,64(2):1015-1028

Subansiri?CRanganadi Doab (confluence country), located in Lakhimpur district, Assam, is one of the worst flood-affected areas in Brahmaputra valley. The Doab is well populated, and land around these rivers is extensively used for cultivation. As means of flood protection, embankments were constructed in the 1950s along the banks of both the rivers. On the other hand, these rivers are dynamic in terms of banklines and other forms of channel changes. Progressive migration of bankline, due to erosion, results in loss of cultivable land. Moreover, it causes breaches in the embankments increasing the severity of flood in the Doab. This paper attempts to study the changes in the banklines of two major rivers in the floodplains of the Subansiri?CRanganadi Doab during 1997?C2009 in the context of the riverine hazards it brings to the floodplain dwellers. The shift of the banklines in Subansiri?CRanganadi Doab, downstream of North Lakhimpur, has been estimated using IRS LISS imageries of 1997 and 2009 in GIS environment. The river Subansiri during the study period has migrated westward and has widened substantially resulting in erosion of an area of ~19.137?km². For Ranganadi, the total area that has been eroded due to channel changes is ~0.897?km². The channel changes are mainly due to concave bank erosion associated with high stages of flow. Channel widening in Subansiri and Ranganadi in the study area during the decades of 1990s and 2000 has led to frequent breaches in the embankments. Lateral erosion and inundation due to embankment failure are the most dominant facets of riverine hazards in the study area as these lead to loss of livelihood. Therefore, it is necessary to incorporate geomorphic changes in formulating flood management programmes.  相似文献   

Clay mineralogical studies on Bijawars of the Sonrai basin: Palaeoenvironmental implications and inferences on the uranium mineralization     

Surendra Kumar Jha  J. P. Shrivastava  C. L. Bhairam 《Journal of the Geological Society of India》2012,79(2):117-134

Clays associated with the Precambrian unconformity-related (sensu lato) uranium mineralization that occur along fractures of Rohini carbonate, Bandai sandstone and clay-organic rich black carbonaceous Gorakalan shale of the Sonrai Formation from Bijawar Group is significant. Nature and structural complexity of these clays have been studied to understand depositional mechanism and palaeoenvironmental conditions responsible for the restricted enrichment of uranium in the Sonrai basin. Clays (<2 μm fraction) separated from indurate sedimentary rocks by disaggregation, chemical treatment and centrifugation were examined using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Presence of tv-1M type illite is inferred from the Rohini and Bandai Members of the Sonrai Formation, indicative of high fluid/rock interaction and super-saturation state of the fluids available in proximity with the uranium mineralization. It is observed that the Sonrai Formation is characterized by kaolinite > chlorite > illite > smectite mineral assemblages, whereas, Solda Formation contains kaolinite > illite > chlorite clays. It has been found that the former mineral assemblage resulted from the alteration process is associated with the uranium mineralization and follow progressive reaction series, indicating palaeoenvironmental (cycles of tropical humid to semi-arid/arid) changes prevailed during maturation of the Sonrai basin. The hydrothermal activity possibly associated with Kurrat volcanics is accountable for the clay mineral alterations.  相似文献   

Anomalous phosphorus episodes during Callovian-Oxfordian times in the Kachchh Basin,western India: Implications for palaeoclimate,productivity, and weathering     

Muthuvairavasamy Ramkumar  Matthias Alberti  Franz T. Fürsich  Dhirendra Kumar Pandey 《Chemie der Erde / Geochemistry》2012,72(2):141-148

The Upper Callovian-Oxfordian strata of the Kachchh Basin, western India, record three positive excursions of phosphorus. They have been documented in three sections of the Chari Formation from different parts of the basin. Corroboration of field and petrographic data with trends of major and trace elemental data and elemental ratios of the strata revealed that these excursions were coeval with reduced chemical weathering in the source area and significant reduction of siliciclastic influx to the depositional sites. The study also revealed the intrabasinal source of P, and minor sea-level fluctuations and resultant episodic sediment recycling as the causative factors. Considering the geographic locations of the three sections, the phosphorus anomalies seem to be controlled by a regional and/or basin-scale process, if not linked with global signals. Temporal resolution of these anomalies suggests that the processes were episodic and related to short term climate/relative sea-level cycles, the durations of which could be unraveled with high-resolution biostratigraphic data.  相似文献   

Petrological and geochemical considerations to predict oil potential of Rajpardi and Vastan lignite deposits of Gujarat, western India     

Prakash K. Singh 《Journal of the Geological Society of India》2012,80(6):759-770

This paper entails the results of the investigations undertaken to assess the oil potential of two lignite deposits, Rajpardi and Vastan, from Gujarat, western India. They are ‘Low rank B’ type lignite. Petrographically, they are enriched in huminite and are low in liptinite and inertinite. Their elevated hydrogen content, in relation to carbon, has probably made them perhydrous in nature and oil prone. The reactivity of these coals during liquefaction has also been discussed in the light of petrofactor. Good correlation has been noticed between oil yield and conversion (r² = 0.999) in both the lignite deposits. The VRr (0.24–0.35% in both lignites), H/C atomic ratio (0.11–1.39 in Rajpardi and 1.09–1.88 in Vastan), reactive maceral content (91.6–99.8 vol % mmf in Rajpardi lignite and 75.5–99.7 vol % in Vastan lignite) and VM_daf (64.8–67.9 wt % in Rajpardi lignite and 42.1–80.0 wt % in Vastan lignite) of these lignites have a favourable range required for a coal to generate oil. Huminite is seen to play a vital role in conversion and maintains a good correlation with it. The calculations show that these lignites have a high conversion (> 95%) and oil yield (> 65%).  相似文献   

Spatial evaluation of groundwater quality in Kazhakuttam block,Thiruvananthapuram district,Kerala     

R. B. Binoj Kumar  M. P. Divya 《Journal of the Geological Society of India》2012,80(1):48-56

The groundwater in the study area generally shows an acidic trend as evidenced by the low pH values, particularly in lateritic aquifers. Spatial assessment indicates that the southern part of the coastal aquifers shows elevated pollution levels during post monsoon season. Most of the groundwater is of Na-Cl facies in post monsoon and which slightly changes to Na-Mg-Cl facies during pre monsoon. Inter relationship between chemical parameters were also studied to understand the groundwater facies. Salinity hazard, percentage of sodium, SAR, integrated SAR and EC and RSC, were considered for judging the usefulness of groundwater for irrigation. Landuse map was prepared and water sample locations were superimposed on it, in a GIS platform, to assess the variation in water quality in different landuse classes. The outcome of the present study indicates that the concentration of certain parameters exceeds the recommended limits and hence mitigation measures are needed to be adopted to ensure safe drinking water.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987112000072     

A.Krishnakanta Singh  R.K.Bikramaditya Singh 《地学前缘(英文版)》2012,3(5):613-634

The Abor volcanics outcroping in the core of the Siang window in the Eastern Himalaya comprise voluminous mafic volcanics (47％-56％ w(SiO2)),with subordinate felsic volcanics (67％-75％ w(SiO2)).The felsi...  相似文献   

Photodegradation of amaranth in aqueous solution catalyzed by immobilized nanoparticles of titanium dioxide     

J. Kumar  A. Bansal 《International Journal of Environmental Science and Technology》2012,9(3):479-484

The use of suspensions of nanoparticles of titanium dioxide in photocatalytic degradation of dye solution has disadvantages of inconvenient separation of fine particles for reuse and limited penetration of light for effective degradation. These problems can be minimized by supporting titanium dioxide on various inert supports. The present study involves the preparation of immobilized titanium dioxide films by three different techniques and characterization of the prepared films. The immobilized films of nanocrystals of titanium dioxide were prepared using sol?Cgel technique, polyvinyl alcohol?Cformaldehyde binder and acrylic emulsion. The photocatalytic performance of the prepared films for degradation of amaranth dye has also been evaluated and compared. Combination of photodegradation and adsorption processes induces strong beneficial effects on removal of dyes. Addition of high adsorption capacity activated carbon to photoactive titanium dioxide in photodegradation of dyes improves the efficiency of dye mineralization. The activated carbon has also been immobilized along with titanium dioxide in the present work to examine the dual effect of photodegradation and adsorption in the removal of amaranth. The films formed with the help of polyvinyl alcohol?Cformaldehyde binder showed better dye degradation capabilities.  相似文献   

Biosorptive behaviour of mango leaf powder and rice husk for arsenic(III) from aqueous solutions     

S. Kamsonlian  S. Suresh  V. Ramanaiah  C. B. Majumder  S. Chand  A. Kumar 《International Journal of Environmental Science and Technology》2012,9(3):565-578

The present study deals with the biosorption of As(III) from aqueous solution using mango leaves powder (MLP) and rice husk (RH) in a batch operation. Scanning electron microscopy and Fourier transformation infrared spectrometry analysis shows the surface texture of biosorbents and metal binding of functional groups of before and after biosorption of As(III). The optimum pH was obtained at 7 and 6 with 7 and 6?g/l of dosage of MLP and RH, respectively. The adsorption of As(III) onto MLP and RH was favourably influenced by an increase in temperature. Equilibrium data were well represented by the Freundlich isotherm model. Nitric acid and ethylenediaminetetra acetic acid was found to be a better eluant for the desorption followed by hydrochloric acid and sodium hydroxide of As(III) with a maximum desorption efficiency of 69.5, 48.5 and 79.4, 86.3?%, respectively. The pseudo-second-order kinetic model was found to best fitted of the experimental data over the equilibrium time at 32?h. The positive values of heat of adsorption (23.89?kJ/mol for MLP and 52.26?kJ/mol for RH) indicate the endothermic nature of the adsorption process. The thermodynamic study showed the spontaneous nature of the sorption of As(III) onto MLP and RH.  相似文献