Sensitivity Analysis of Coal Rib Stability for Internal Mine Dump in Opencast Mine by Finite Element Modelling     

Tushar Gupta  Rajesh Rai  Ashok Jaiswal  B. K. Shrivastva 《Geotechnical and Geological Engineering》2014,32(3):705-712

The present paper discusses the impact of the geometrical parameters of the coal rib and the mine dump on the stability of the coal rib. The geometrical parameters such as the slope angle, the height of dragline dump, the height of main dump, the gradient of seam and the thickness of coal rib have been considered as input to the numerical model for the stability analysis of the coal rib. Sensitivity analysis has been performed based on the results of the analysis in term of factor of safety of the coal rib. The input parameters have been classified in terms of significance (i.e. very high significance, high significance medium significance and low significance). The factor of safety is more influenced by highly significant parameters. The height and the slope angle of dragline dump and the thickness of the coal rib are highly significant parameters for the stability of the coal rib. The gradient of the seam is a medium significant parameter whereas, height of main dump and the number of dragline cut dump are low significant parameters for stability of coal rib.  相似文献   

Assessment of impervious surface growth in urban environment through remote sensing estimates     

Anindita Sarkar Chaudhuri  Prafull Singh  S. C. Rai 《Environmental Earth Sciences》2017,76(15):541

The fast growth in population and expansion of urban built area has led to the transformation of the natural landscape into impervious surfaces. Remote sensing-based estimate of impervious surface area (ISA) has emerged as an important indicator for the assessment of water resources depletion in urban areas and developed a correlation between land-use change and their potential impact on urban hydrology. In the present work, a remote sensing-based Impervious Surface Area (ISA) was carried out for New Okhla Industrial Development Authority (NOIDA) city, one of the fastest growing cities in National Capital Region (NCR) of India. The impervious surface area (ISA) of NOIDA was calculated for the years 2001, 2007 and 2014 using multi-temporal LANDSAT thermal data by applying linear spectral mixing analysis (LSMA) techniques to monitor the growth rate of impervious surface. The results observed by analysis of multi-temporal satellite images show an extreme temporal change in the growth of ISA in the city. The ISA observed for the year 2001 is 28 sq.km; in 2007, its increase was 48 sq.km and was 132 in 2014. The results were observed from this work through the use of satellite data which is very important for water resource management, planning and prediction of ISA impact on hydrology.  相似文献   

Particle precipitation in Brazilian geomagnetic anomaly during magnetic storms     

N.B. Trivedi  D.B. Rai  I.M. Martin  J.M. Da Costa 《Planetary and Space Science》1973,21(10):1699-1704

Particle precipitation in Brazilian geomagnetic anomaly during magnetic storms is investigated using riometer and VLF propagation data. It is found that during large storms the changes in the ionosphere caused by particle precipitation are detectable. There is a good correlation between the behavior of the absorption and the variations of the magnetic field intensity during different phases of a storm. In particular, there seems to be a close relationship between the precipitation of high energy particles and short-period fluctuations of the magnetic field intensity of the order of 5–6 min. During the main phase of the storm, when the field intensity reaches its minimum, the flux of soft electrons also plays a significant role in producing absorption. The nature of precipitation associated with a sudden commencement appears to be more complex; the predominance of low or high energy particle flux may depend on the magnitude of the field increase. The amplitude and phase records of VLF signals also show the effect of the disturbance, but it is difficult to correlate the changes in these records with the features observed on the magnetogram, because only a small part of the propagation path lies in the region of the anomaly. A more detailed analysis of riometer data from different stations and VLF phase and amplitude records for different paths will be helpful in understanding the mechanism of particle precipitation associated with magnetic disturbances. In future experiments it may also be fruitful to look for detectable radiation emitted by the precipitating electrons, for example, Cherenkov and synchrotron radiation.  相似文献   

Impact of forest degradation on streamflow regime and runoff response to rainfall in the Garhwal Himalaya,Northwest India     

Nuzhat Q. Qazi  L. Adrian Bruijnzeel  Shive Prakash Rai  Chandra P. Ghimire 《水文科学杂志》2017,62(7):1114-1130

Baseflows have declined for decades in the Lesser Himalaya but the causes are still debated. This paper compares variations in streamflow response over three years for two similar headwater catchments in northwest India with largely undisturbed (Arnigad) and highly degraded (Bansigad) oak forest. Hydrograph analysis suggested no catchment leakage, thereby allowing meaningful comparisons. The mean annual runoff coefficient for Arnigad was 54% (range 44–61%) against 62% (53–69%) at Bansigad. Despite greater total runoff Q_t (by 250 mm year^–1), baseflow at Bansigad ceased by March, but was perennial at Arnigad (making up 90% of Q_t vs. 51% at Bansigad). Arnigad storm flows, Q_s, were modest (8–11% of Q_t) and occurred mostly during monsoons (78–98%), while Q_s at Bansigad was 49% of Q_t and occurred also during post-monsoon seasons. Our results underscore the importance of maintaining soil water retention capacity after forest removal to maintain baseflow levels.