Assessment of tunnel instability—a numerical approach   总被引：2，自引：1，他引：1  

Amit K. Verma  T. N. Singh 《Arabian Journal of Geosciences》2010,3(2):181-192

This paper outlines the application of numerical modeling to predict deformation and stability of tunnel to be excavated in Bansagar, M.P., India. To meet the ever-increasing demand of transportation, energy, and other infrastructure projects, a large volume of rock tunneling is being carried out throughout the world. The geotechnical properties along the route of the 1,800-m long tunnel in the Bansagar region of India have been studied. The rock mass rating and rock mass quality systems were employed for empirical rock mass quality determination. Numerical analysis for the stress–strain distribution of the tunnel excavation and support systems was also carried out. In order to simulate the excavation of tunnel (NATM) at a depth of 150 m below the ground , a series of finite element analyses using Mohr-coulomb elasto-plastic constitutive model has been carried out using PLAXIS 2D. The stability of tunnel has been analyzed, and stress pattern have been discussed.  相似文献   

Tectonic evolution of the Aravalli orogen (NW India): an inverted Proterozoic rift basin?     

P. K. Verma  R. O. Greiling 《International Journal of Earth Sciences》1995,84(4):683-696

The Aravalli mountain range (AMR) in the northwestern part of the Indian Peninsula consists of two main Proterozoic metasedimentary and metaigneous sequences, the Aravalli and Delhi Supergroups, respectively, which rest over the Archaean gneissic basement. A synthesis and reinterpretation of the available geological, geochronological and geophysical data, including results of own field work and geophysical interpretations pertaining to the AMR, indicate its origin as an inverted basin: rifting into granitoid basement began ca. 2.5; Ga ago with Aravalli passive rifting (ca. 2.5–2.0 Ga) and Delhi active rifting (ca. 1.9–1.6 Ga). Associated mafic igneous rocks show both continental and oceanic tholeiitic geochemistry and are comparable with Phanerozoic, rift-related magmatic products. Available data showed no conclusive evidence for oceanic lithoshere and island-arc/active margin magmatic activity in the AMR. Subsequent inversion and orogeny (Delhi orogeny, ca. 1.5-1.4 Ga) lead to complex deformation and metamorphism. Only in the western and central zones has the basement been involved in this mid-Proterozoic (Delhi) deformation, whereas it is unaffected in the eastern part, except for local shear zones mainly along the basement/cover interface. The grade of metamorphism increases from the greenschist facies in the east to the amphibolite facies in the west with local HP assemblages. These latter are explained by rapid burial and exhumation of thin and cool continental lithosphere. Subsequently, during a final, mild phase of inversion, the Vindhyan basins consisting mainly of sandstones, limestones and shales, flanking the AMR formed which are comparable to foreland basins. The tectonic evolution of the AMR is therefore interpreted as an example of a major inverted continental rift and of a Proterozoic intra-continental orogen.  相似文献   

Propagation of surface waves on the surface of a non-homogeneous aeolotropic cylindrical shell     

B. G. Verma  Vinod Kumar Srivastava 《Pure and Applied Geophysics》1973,110(1):1939-1945

Summary The object of the present paper is to investigate the propagation of surface waves on a non-homogeneous aeolotropic cylindrical shell surrounded by vacuum. The elastic constantsc _ij (i, j=1,2...) and density of the material of the shell are assumed to be of the form and respectively, where _ij, ₀ are constants andk ₁,k ₂ are any integers.  相似文献   

Errata     

J. G. Negi  S. K. Verma 《Geophysical Prospecting》1973,21(3):584-584

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2-D inversion of geomagnetic deep-sounding data near Ujjain-Guna, India     

S. N. Prasad  S. K. Verma  J. Pek  V. &#;erv 《Geophysical Journal International》1993,113(3):767-775

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Alterations in Certain Organic Components and Serum Electrolytes in Notopterus notopterus Chronically Exposed to Phenolic Compounds     

S. R. Verma  Saroj Rani  R. C. Dalela 《洁净——土壤、空气、水》1982,10(1):31-40

• The present investigation was undertaken to evaluate the effects of three sublethal concentrations (1/10th, 1/15th and 1/20th fractions of 96 h LC₅₀) of phenol (P), dinitrophenol (DNP), pentachlorophenol (PCP) and their antagonistic [(PCP + DNP)/P], additive [(DNP + P)/PCP] and synergistic [(P + DNP)/PCP] combinations, on several organic and inorganic components of haemopoetic systems of Notopterus notopterus after 30 d of exposure.
• Glucose, lactate, total phosphorus, non-protein nitrogen, sodium, potassium, magnesium, calcium, iron and chloride were found to be increased in most cases while protein and cholesterol were found to be decreased.
• It has been concluded that these alterations in blood parameters might be due to a damage or hyperactivity of liver, kidney and endocrine glands, the main centres for controlling the tissue metabolism.

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Histological Changes in a Few Tissues of Notopterus notopterus Induced by Sublethal and Lethal Concentrations of Pulp,Paper and Mixed Pulp and Paper Wastes     

S. R. Verma  S. G. R. Shukla  R. C. Dalela 《洁净——土壤、空气、水》1979,7(1):77-86

In the present work, histological changes in the gill, liver, kidney and intestine of Notopterus notopterus, induced by pulp waste, paper waste and mixed pulp and paper waste, have been studied both at sublethal and lethal concentrations. The pulp waste produces much more histological changes both at sublethal and lethal concentrations in the gill, liver, kidney and intestine as compared to paper waste and mixed pulp and paper waste. The changes are much more remarkable in the case of sublethal concentration, as compared to a lethal concentration. In a sublethal concentration, the localized necrosis, atrophy and partial and total liquefaction of epithelial cells, pilaster cells, mucous cells of the gill, hepatic cells of the liver, mesenchymatous cells, renal tubule cells and Bowman's capsule of the kidney, mucosal and submucosal cells and blood vessels of intestine have been observed. In lethal concentration, the changes are much more marked in the gill, as compared to the liver, kidney and intestine. The histological changes, produced in the different types of cells and in the tissue as a whole, can be correlated with the different chemical components present in the pulp waste, paper waste and mixed pulp and paper waste.  相似文献   

Studies on the Toxicity of a few Pesticides on Colisa fasciatus and Notopterus notopterus with Reference to Histopathology and Histochemistry. Part 1: Bioassay Studies     

S. P. Gupta  S. R. Verma  R. C. Dalela 《洁净——土壤、空气、水》1979,7(2):223-238

An attempt has been made to study the toxicity of two commonly used pesticides aldrin (organochlorine) and ethyl-parathion (organophosphorus) to the fish Colisa fasciatus (Anabantidae) and Notopterus notopterus (Notopteridae). During bioassay studies, the behaviour of the fishes was recorded. The aldrin concentration used lies between 0.021 mg/1 and 0.042 mg/1 for C. fasciatus and 0.00056 mg/1 and 0.00135 mg/1 for N. notopterus. The ethyl-parathion concentration used lies between 1.8 mg/1 and 3.7 mg/1 for C. fasciatus and 0.49 mg/1 and 1.00 mg/1 for N. notopterus.

• – The effect of lethal aqueous concentrations of pesticides on the Fishes prior to death are usually manifested by excitation, erratic swimming ability, difficulty in respiration, increasing in ventilation rate, jerky movements of body and fin fast, up- and downward movements, convulsions, loss of equilibrium, loss of the original colour of the body skin and the excess secretion of mucus by the gills and the body wall.
• – the TL_m values for 24, 48 and 96 hours of exposition are determined for both species of fish and both pesticides at the following variables:

• ? three levels of temperature,
• ? three levels of dissolved oxygen,
• ? three levels of pH,
• ? three fish sizes.

• – statistical analysis of variance shows, that all variables have a significant effect on the TL_m values of both pesticides for both fish species;
• – Aldrin (chlorinated hydrocarbon) is more toxic than ethylparathion (organophosphate) at all variables;
• – Colisa fasciatus is the more resistant species than Notopterus notopterus.
• – the relationship between the total number of the fishes N₀, survival numbers N and time t can be expressed by a mathematical formula as:
• – the harmless concentration to C. fasciatus ranged from 0.0049 mg/1 to 0.0161 for aldrin, 0.54 mg/1 to 0.99 mg/1 for ethyl-parathion and to N. notopterus from 0.00012 mg/1 to 0.00045 mg/1 for aldrin, 0.10 mg/1 to 0.21 mg/1 for ethyl-parathion;
• – the aldrin should be diluted at least 4000 times and ethyl-parathion 320 times of its actual concentration.

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Biocides in Relation to Water Pollution Part I: Bioassay Studies on the Effects of a few Biocides on Fresh Water Fish,Channa gachua     

R. C. Dalela  S. R. Verma  M. C. Bhatnagar 《洁净——土壤、空气、水》1978,6(1):15-25

• - In the present paper the toxicity of four biocides, endrin, thiodon, malathion and phosvel, has been measured by performing static bioassay experiments with Channa gachua as test fish to establish the median Tolerance Limits (TL_m and TL₅₀).
• - The results of bioassay experiments indicate that the fish is harmed even at a very low concentration of these biocides. The values of TL_m are 0.0076, 0.0073, 0.00695 and 0.0068 for endrin; 0.01120, 0.01088, 0.01069 and 0.01064 for thiodon; 9.20, 8.10, 7.90 and 7.60 for malathion and 32.90, 32.10, 31.65 and 31.15 mg/l for phosvel for the time interval of 24, 48, 76 and 96 hours, respectively.
• - As indicated by TL_m's, endrin is most toxic and phosvel least. Thiodon and malathion came in a descending order between endrin and phosvel.
• - During bioassay studies, the effect of some variables, like temerature, pH and fish-size, on TL_m's has also been observed. They gave the following results.
• a) An increase in temperature increased the toxicity of all the biocides.
• b) An increase in pH decreased the TL_m as such, making the biocides more toxic to Channa gachua.
• c) For larger fishes, the biocide solutions were less toxic, but the same solutions were more toxic to fishes of a smaller size.
• - The safe harmless concentrations of endrin, thiodon, malathion and phosvel are - 0.00289 mg/l, 0.00337 mg/l, 1.88365 mg/l and 9.16736 mg/l, respectively.

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Structure of the foot-hills of the Himalayas     

G. S. Verma 《Pure and Applied Geophysics》1974,112(1):18-26

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