Effect of Arching on Uplift Capacity of Single Piles     

Amit Shelke  Nihar Ranjan Patra 《Geotechnical and Geological Engineering》2009,27(3):365-377

An analytical method has been proposed to predict the ultimate uplift capacity of single vertical piles embedded in sand considering arching effect. The present analysis takes into consideration of various pile and soil parameters such as length (L), diameter (d) of the pile, angle of internal friction of soil (ϕ), soil pile friction angle (δ) and unit weight of soil (γ). A modified value of coefficient of lateral earth pressure in uplift has been developed considering the arching effect of soil. A comparative assessment of the uplift capacity of piles predicted by using proposed theory and the existing available theories is made with the existing field and model test results. It has been observed that the present model considering the arching effect predicts the results closer.  相似文献   

The role of kerogen constituents in oil generation in the Gevar'am Formation (Lower Cretaceous), Israel     

O. Amit 《Organic Geochemistry》1979,1(4):237-241

Kerogen from various samples of the Gevar'am Formation (Early Cretaceous, Israel) were analyzed for their elemental composition, and by I.R. and ESR spectroscopy. The results were compared with other organochemical characteristics of the basin (Amit, 1978, Bull. Am. Assoc. Pet. Geol., V. 62 p. 827–836). The types of organic material and their role in the formation of oil were investigated. It appears that the kerogen is mostly constituted of terrestrially derived organic matter. A small amount of marine-derived organic matter is also inferred. The kerogen of terrestrial origin is a poor oil producer and is expected to generate oil only at a higher stage of maturation than the Gevar'am Formation has attained. Any hydrocarbons that have been generated in this formation were probably generated from that part of the kerogen thought to be marine derived. Thus the Gevar'am Formation is considered as a potential source rock which has generated only a small amount of oil.  相似文献   

Interpretation of spring recession curves   总被引：4，自引：0，他引：4  

Amit H  Lyakhovsk V  Katz A  Starinsky A  Burg A 《Ground water》2002,40(5):543-551

Recession curves contain information on storage properties and different types of media such as porous, fractured, cracked lithologies and karst. Recession curve analysis provides a function that quantitatively describes the temporal discharge decay and expresses the drained volume between specific time limits (Hall 1968). This analysis also allows estimating the hydrological significance of the discharge function parameters and the hydrological properties of the aquifer. In this study, we analyze data from perennial springs in the Judean Mountains and from others in the Galilee Mountains, northern Israel. All the springs drain perched carbonate aquifers. Eight of the studied springs discharge from a karst dolomite sequence, whereas one flows out from a fractured, slumped block of chalk. We show that all the recession curves can be well fitted by a function that consists of two exponential terms with exponential coefficients alpha1 and alpha2. These coefficients are approximately constant for each spring, reflecting the hydraulic conductivity of different media through which the ground water flows to the spring. The highest coefficient represents the fast flow, probably through cracks, or quickflow, whereas the lower one reflects the slow flow through the porous medium, or baseflow. The comparison of recession curves from different springs and different years leads to the conclusion that the main factors that affect the recession curve exponential coefficients are the aquifer lithology and the geometry of the water conduits therein. In normal years of rainy winter and dry summer, alpha1 is constant in time. However, when the dry period is longer than usual because of a dry winter, alpha1 slightly decreases with time.  相似文献   

Correction to: Hydro-meteorological and agricultural trends in water-scarce Karha Basin,western India: current and future scenario     

Rahul S. Todmal  Mahendra S. Korade  Amit G. Dhorde  Rajendra B. Zolekar 《Arabian Journal of Geosciences》2018,11(12):317

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Oldest Asian Record of Snapping Shrimps (Malacostraca: Alpheidae) from the Kutch Basin, Western India and Associated Biota: Biostratigraphic, Paleoenvironmental and Paleoecological Significance     

Vivesh V. KAPUR  Kamlesh KUMAR  Pranav J. PANDYA  Amit K. GHOSH  Arindam CHAKRABORTY  Anupam SHARMA  Gaurav CHAUHAN  M. G. THAKKAR 《《地质学报》英文版》2022,96(6):1867-1883

The oldest Asian record of alpheid shrimps, assigned to genus Alpheus, based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin, western India reported herein, extends the fossil record of the family Alpheidae from Asia by ~22 million years. An early Miocene (Aquitanian) age is estimated based on the associated assemblage of calcareous nannofossils, Sphenolithus disbelemnos, Cyclicargolithus floridanus, and Reticulofenestra haqii. The co-occurring microbiota includes bony fish otolith remains, identified as “genus Gobiidarum”, isolated teeth of Dasyatis rays, Sphyrna sharks, and teleosts, ctenoid and placoid scales, ostracods, belonging to the genera Paractinocythereis, Alocopocythere, Ruggieria? Aglaiocypris, Bairdoppilata, and echinoid spines. Taken together, the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy, X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow (neritic) to coastal marine (intertidal) depositional paleoenvironment.  相似文献   

Influence of Overlying Roof Strata on Rib Design in Mechanised Depillaring     

Ashok Kumar  Dheeraj Kumar  Amit Kumar Verma  Arun Kumar Singh  Sahendra Ram  Rakesh Kumar 《Journal of the Geological Society of India》2018,91(3):341-347

Depillaring of the existing pillars (square or rectangular in shape) by continuous miner provides irregular shaped ribs. An assessment of strength of such a rib becomes a difficult task. Literature review finds a number of approaches for the rib design but the scope of straight forward application of these approaches is limited due to the uniqueness of geo-mining conditions of the Indian coalfields. This review also finds that a wide spectrum of moderate roof conditions is yet to be properly addressed. Field studies at some depillaring operations in Indian coalfields indicated the influence of roof strata over the stability of a rib is considerably high. A systematic study of the roof strata influence on simulated models provided interesting results. A model for rib design is conceived on the basis of the simulation results. Discussing couple of field experiences of rib stability during mechanised depillaring under two different types of roof strata of Indian coalfields, this paper presents some results of the simulation along with the conceived model of a rib design.  相似文献   

Local Site Effect Due to Past Earthquakes in Kolkata     

Amit Shiuly  R. B. Sahu  Saroj Mandal  Narayan Roy 《Journal of the Geological Society of India》2018,91(4):400-410

Kolkata, capital of West Bengal, India, presently congested with moderate to high rise buildings, has undergone low to moderate damages due to past earthquakes. The city is situated on the world’s largest delta island with soft thick alluvial soil layer. In this study, an attempt has been made to study ground response due to a number of past earthquakes, 1897 Shillong earthquake, 1964 Calcutta earthquake and 2011 Sikkim earthquake, for the purpose of preliminary microzonation of the Kolkata city. For this, synthetic ground motions have been generated at bedrock level by stochastic method. By using 1D wave propagation technique, the synthetic ground motion has been computed at surface level for 144 borehole locations in the city. Contours of PGA, PGV and PGD parameters in the city have been drawn for these three earthquakes. Response spectra for these three earthquakes have also been computed and an optimum response spectrum has been determined. A good correlation has been obtained with predicted ground motion at surface level of the city with the reported intensity and damages occurred in buildings of Kolkata during past earthquakes. The scenario of simulated ground motion for the past three earthquakes depicts that Kolkata city is very much prone to damages even due to moderate far and near source earthquakes.  相似文献   

Effect of uncertainty in $$V_{\mathrm{S}}{-}N$$ correlations on seismic site response analysis     

Narayan Roy  Amit Shiuly  R B Sahu  Ravi S Jakka 《Journal of Earth System Science》2018,127(7):103

This paper studies the reliability of the calculated shear-wave velocity (\(V_{\mathrm{S}}\)) from different available \(V_{\mathrm{S}}\) and SPT-N correlations in terms of seismic site response analysis. In the present study, various \(V_{\mathrm{S}}\)–N correlations developed for different regions around the globe have been used to calculate the bound of \(V_{\mathrm{S}}\) variations with depth at three different sites in Kolkata city. This bound has later been used to generate the random \(V_{\mathrm{S}}\) profiles using the Monte Carlo simulation. Equivalent linear site response analysis has been performed to study the response of those generated profiles under different input motion excitations. Strong-to-weak ground motion records have been used for this purpose. The amplification spectra of the generated \(V_{\mathrm{S}}\) profiles using all soil types and specific soil-type \(V_{\mathrm{S}}\)–N correlations show significant variations. The study also shows that the \(V_{\mathrm{S}}\)–N correlation may result in quite different \(V_{\mathrm{S},30}\) values and subsequently it may lead to the different site classes according to the NEHRP 2003 classification. So, the random choice of the \(V_{\mathrm{S}}\)–N correlation, where the direct measurement of \(V_{\mathrm{S}}\) is not available, may affect the outcome of seismic hazard analysis significantly. The study points out the need for accurate estimation of the \(V_{\mathrm{S}}\) profile either from in-situ determination or using site-specific correlation.  相似文献   

Random Forest Tree Based Approach for Blast Design in Surface Mine     

Arvind K. Mishra  Silao V. Ramteke  Phalguni Sen  Amit Kumar Verma 《Geotechnical and Geological Engineering》2018,36(3):1647-1664

Blasting is one of the primary mining operations for extracting minerals and ores however, if not designed properly, may have a varying degree of environmental and socio-economic impact in and around mining areas. In Indian mining industry, blast designs are fundamentally based on the experience and capability of the blasting crew and its assessment is more qualitative in nature, based on conventional trial and error basis. With the change in site geology and geotechnical parameters, the blast design parameters also require alterations, which can be standardized with the development of an intelligent system such as neural network. In this paper, the concept of artificial neural network and random forest algorithm has been used for better blast designs. Over 120 blast results from an opencast coal mine have been used for prediction of burden and energy factor with blast hole diameter, bench height to stemming ratio, nature of strata and average fragment size as input parameters. Out of 120 data sets 85 data sets recorded at a surface coal mine was used to train the model and 20 for the validation. Co-efficient of determination and root mean square error was chosen as the indicators to identify the optimum neural network and random forest model. The root mean square values obtained for energy factor is 0.153 while it is 0.1947 for burden. Similarly, the RMSE values obtained using random forest tree algorithm is 0.48 for burden while 50.76 for energy factor. The results revealed that random forest tree network system has potential to design better blast that is not generic and can be a potential tool for blasting engineers to design optimum blast for the mines.  相似文献   

Water Level Retrieval Using SARAL/AltiKa Observations in the Braided Brahmaputra River,Eastern India     

Amit Kumar Dubey  Praveen Gupta  Subashisa Dutta  Raghvendra Pratap Singh 《Marine Geodesy》2015,38(3):549-567

In this study, water level retrieval over the Brahmaputra river was done using different retracking algorithms for the 40 Hz waveform data of SARAL/AltiKa satellite. Water level was retrieved at 10 different locations of the river to evaluate the performance and accuracy of Ka band altimeter over the braided river system. Different retracking algorithms such as ice-1, ice-2, threshold, and beta parameter were used to retrieve water levels. A correlation and error analysis between the in-situ and satellite altimetry derived river levels was carried out for all the stations. Performance and accuracy analysis has established that water level can be retrieved with less than 40 cm root mean square error (RMSE) for most of the braided reaches of the river. The statistical analysis have found that Beta parameter algorithm has performed best in most of the cases amongst the different retracking algorithms used in this study. The water levels derived from 10 different locations were used to generate water surface elevation profiles for the monsoon and nonmonsoon periods. The water levels and the water surface profiles derived from satellite altimetry indicate the potential use of altimeters for the parameterization and calibration of river hydrological, hydrodynamic and sediment transport models.  相似文献