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921.
通过对运用介质互换测定空气衰减系数的理论进行分析,探讨了介质互换测定空气衰减系数的适用范围和限制条件,并得出计算空气伽马衰减系数的修正公式,计算结果表明效果显著,对航空伽马测量工作中准确测定空气衰减系数有好的指导意义。 相似文献
922.
Jun-Mo Kim 《Mathematical Geology》2005,37(8):929-941
On the basis of vectorial formulation, a series of relatively simple closed-form mathematical equations is presented to determine
the direction cosines of the local coordinate axes associated with planar and linear structures in an anisotropic geologic
material from their geologic angle measurements (i.e., strike and dip for planar structures and trend and plunge for linear
structures). The equations are then applied to calculation of global anisotropic hydraulic conductivity and elastic stiffness
tensors with respect to the geographical coordinate axes from their local counterparts with respect to the material symmetry
axes. 相似文献
923.
Double Porosity Finite Element Method for Borehole Modeling 总被引:2,自引:0,他引:2
Summary. This paper considers the mechanical and hydraulic response around an arbitrary oriented borehole drilled in a naturally fractured formation. The formation is treated as a double porosity medium consisting of the primary rock matrix as well as the fractured systems, which are each distinctly different in porosity and permeability. The poro-mechanical formulations that couple matrix and fracture deformations as well as fluid flow aspects are presented. A double porosity and double permeability finite element solution for any directional borehole drilled in the fractured porous medium is given. Compared with conventional single-porosity analyses, the proposed double-porosity solution has a larger pore pressure in the matrix and a smaller tensile stress in the near-wellbore region. The effects of time, fracture, mud weight, and borehole inclination in the double-porosity solution are parametrically studied to develop a better understanding of physical characteristics governing borehole problems. 相似文献
924.
Ahmed Benamar HuaQing Wang Nasre-dine Ahfir Abdellah Alem Nicolas Masséi Jean-Paul Dupont 《Comptes Rendus Geoscience》2005,337(5):497-504
We study in this paper the transport and deposition of suspended particles in saturated porous media. Some chromatographic short-pulse tests were performed in a laboratory column with a tracer and two types of suspended particles. A mathematical model was used to determine the hydrodispersive parameters and deposition rates from the breakthrough curves. The results show that the fitted parameters obtained vary with the flow rate and the characteristics of the suspended particles. We also observe, at high flow rates, that particles have a migration velocity higher than that of the conservative tracer. To cite this article: A. Benamar et al., C. R. Geoscience 337 (2005). 相似文献
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928.
Yu Haizhen Zhao Wenguang Wang Ren Li Jianguo He Yang 《中国地质大学学报(英文版)》2005,16(4):340-344
INTRODUCTION Theexploitationofoffshorenaturalresourcesin thetropichaspresentedgeotechnicalengineerswith theproblemofdealingwithinsitucarbonatesedi mentsinharshconditionsforwhichfewengineering dataareavailable.Thecarbonatesedimentsaresub jectedtolargestaticstressesduetotheweightof foundationstructuresaswellascyclicstressesdueto waveaction,andinsomecases,earthquakeloading.Ithasbeenprovedthatthenatureofcyclicstresschangesoccurringintheseabeddepositduetowave loadinginvolvesacontinuousrotationo… 相似文献
929.
An absorbing boundary for saturated porous media is developed that can be used for transient analyses in the time domain. The elastic constitutive equations for the saturated porous media follow Bowen's formulation. The method consists of applying viscous tractions along the artificial boundary. The absorbing boundary behaviour is assumed linear and isotropic. Hadamard's conditions provide the speeds of the dilatational and shear waves that propagate in saturated porous media. Since these expressions are frequency independent, the intensities of the viscous tractions are evaluated in the time domain, and the two dilatational waves are accounted for. The viscous tractions are defined from the drained characteristics, assuming an infinite permeability, at variance with the traditional ‘undrained’ method based on undrained characteristics and a null permeability. Solid media and materials with low permeability are also retrieved as subcases. The results show that, at no additional cost, this ‘drained’ method is more accurate for all permeabilities than the ‘undrained’ method, which disregards the existence of the second dilatational wave. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
930.
The interacting inclusion model of wave-induced fluid flow 总被引:1,自引:0,他引:1
Morten Jakobsen 《Geophysical Journal International》2004,158(3):1168-1176