A high strain‐rate constitutive model for sand and its application in finite‐element analysis of tunnels subjected to blast     

William Higgins  Tanusree Chakraborty  Dipanjan Basu 《国际地质力学数值与分析法杂志》2013,37(15):2590-2610

The paper presents a constitutive model for simulating the high strain‐rate behavior of sands. Based on the concepts of critical‐state soil mechanics, the bounding surface plasticity theory and the overstress theory of viscoplasticity, the constitutive model simulates the high strain‐rate behavior of sands under uniaxial, triaxial and multi‐axial loading conditions. The model parameters are determined for Ottawa and Fontainebleau sands, and the performance of the model under extreme transient loading conditions is demonstrated through simulations of split Hopkinson pressure bar tests up to a strain rate of 2000/s. The constitutive model is implemented in a finite‐element analysis software Abaqus to analyze underground tunnels in sandy soil subjected to internal blast loads. Parametric studies are conducted to examine the effect of relative density and type of sand and of the depth of tunnel on the variation of stresses and deformations in the soil adjacent to the tunnels. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Ejections of population III objects seen as blueshifted QSOs?     

Shirin Haque-Copilah  D. Basu  M. Valtonen 《Journal of Astrophysics and Astronomy》1997,18(1):73-85

We discuss the origin of the optical jets and the apparently associated cloud of QSOs in NGC 1097. There is a simple explanation for the jets in terms of ejection trails of supermassive black holes. In this interpretation, the trails provide the first direct evidence for the non-conservation of linear momentum in a two black hole collision. The cluster of quasars at the end of the jets is then naturally associated with objects which have been ejected by the merging pair of black holes. It is possible to interpret the spectral lines of these QSOs such that half of them are blueshifted relative to NGC 1097 while the other half is redshifted. We infer that the objects in the QSO cluster are not real QSOs but probably collapsed objects of lower mass. We argue that these objects are likely to represent the hypothetical population III black holes of Carretal.  相似文献   

Apollo 12 ropy glasses revisited   总被引：1，自引：0，他引：1  

S. J. Wentworth  D. S. McKay  D. J. Lindstrom  A. Basu  R. R. Martinez  D. D. Bogard  D. H. Garrison 《Meteoritics & planetary science》1994,29(3):323-333

Abstract— We analyzed ropy glasses from Apollo 12 soils 12032 and 12033 by a variety of techniques including SEM/EDX, electron microprobe analysis, INAA, and ³⁹Ar-⁴⁰Ar age dating. The ropy glasses have KREEP-like compositions different from those of local Apollo 12 mare soils; it is likely that the ropy glasses are of exotic origin. Mixing calculations indicate that the ropy glasses formed from a liquid enriched in KREEP and that the ropy glass liquid also contained a significant amount of mare material. The presence of solar Ar and a trace of regolith-derived glass within the ropy glasses are evidence that the ropy glasses contain a small regolith component Anorthosite and crystalline breccia (KREEP) clasts occur in some ropy glasses. We also found within these glasses clasts of felsite (fine-grained granitic fragments) very similar in texture and composition to the larger Apollo 12 felsites, which have a ³⁹Ar-⁴⁰Ar degassing age of 800 ± 15 Ma (Bogard et al, 1992). Measurements of ³⁹Ar-⁴⁰Ar in 12032 ropy glass indicate that it was degassed at the same time as the large felsite although the ropy glass was not completely degassed. The ropy glasses and felsites, therefore, probably came from the same source. Most early investigators suggested that the Apollo 12 ropy glasses were part of the ejecta deposited at the Apollo 12 site from the Copernicus impact Our new data reinforce this model. If these ropy glasses are from Copernicus, they provide new clues to the nature of the target material at the Copernicus she, a part of the Moon that has not been sampled directly.  相似文献   

A study of possible temporal and latitudinal variations in the properties of the solar tachocline     

Sarbani Basu  H. M. Antia 《Monthly notices of the Royal Astronomical Society》2001,324(2):498-508

Temporal variations of the structure and the rotation rate of the solar tachocline region are studied using helioseismic data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) obtained during the period 1995–2000. We do not find any significant temporal variation in the depth of the convection zone, the position of the tachocline or the extent of overshoot below the convection zone. No systematic variation in any other properties of the tachocline, like width, etc., is found either. The possibility of periodic variations in these properties is also investigated. Time-averaged results show that the tachocline is prolate with a variation of about 0.02 R_⊙ in its position. Neither the depth of the convection zone nor the extent of overshoot shows any significant variation with latitude.  相似文献   

A multivariate statistical study of copper mineralization in the central section of Mosaboni Mine, Eastern Singhbhum, India     

A. K. Saha  S. N. Sarkar  Swapna Basu  Dhruba Ganguly 《Mathematical Geology》1986,18(2):215-235

A multivariate statistical analysis was carried out with log-transformed values of Cu, Ni, Co, Pb, Zn, Ag, Cr, Mn, Ca, and Sr in several sets of samples collected across the mineralized base metal zone in sheared soda granite, feldspathic schist, and chlorite schist from the central section of Mosaboni Mine of the famous Singhbhum Copper Belt of eastern India. Linear correlation coefficient matrices of two sets of ore samples (>0.5% Cu)—one from levels 18 and 21 and the other from levels 25 and 28—indicate two well-defined and distinct clusters comprising Cu, Ni, Co, Pb, and Zn on one hand and Ca, Sr, and Mn on the other. Varimax-rotatedR-mode factor analysis of two above-noted sample sets, taken along with available geologic information, indicates that over 80% of the variability in data matrices for 9–10 elements can be accounted for by four distinct processes: (a) an early phase of copper mineralization which apparently replaced Mn, Ca, and Sr in the host rock; (b) a silicate-cum-oxide phase of crystallization/recrystallization of host rock; (c) remobilization of sulfide-forming ore elements (Cu, Ni, Co, Pb, and Zn); and (d) a phase of mineralization of Ag which appears to have replaced Cr, Ca and Cu. Process (c) was quantitatively most important. Factor score studies are suggestive of preferred introduction of Ni, Co, Pb, and Zn along central parts of preexisting copper-mineralized zones.  相似文献   

Estimation of Raft Settlement Based on Linear Elastic Finite Element Analysis     

Bhartiya  Priyanka  Chakraborty  Tanusree  Basu  Dipanjan 《Geotechnical and Geological Engineering》2022,40(6):2907-2919

Geotechnical and Geological Engineering - A detailed parametric study based on linear-elastic three-dimensional finite element (FE) analysis with proper raft–soil interaction is performed for...  相似文献   

Precambrian crustal growth and tectonics: introduction     

Vinod K. Singh  Ram Chandra  Asish R. Basu  Surendra P. Verma  Tapas K. Biswal 《International Geology Review》2015,57(11-12):v-viii

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Reply to: Comments on “Trace element and isotopic evidence for Archean basement in the Lonar crater impact breccia, Deccan volcanic province” by Ramananda Chakrabarti and Asish R. Basu     

Ramananda Chakrabarti  Asish R. Basu  Arundhuti Ghatak 《Earth and Planetary Science Letters》2006,250(3-4):669-670

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The effect of a finite mass reservoir on the collapse of spherical isothermal clouds and the evolution of protostellar accretion     

E. I. Vorobyov  Shantanu Basu 《Monthly notices of the Royal Astronomical Society》2005,360(2):675-684

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Asteroseismic determination of helium abundance in stellar envelopes     

Sarbani Basu  Anwesh Mazumdar  H. M. Antia  Pierre Demarque 《Monthly notices of the Royal Astronomical Society》2004,350(1):277-286

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