黄土台缘滑坡地表水入渗问题分析   总被引：7，自引：0，他引：7  

许领  李宏杰  吴多贤 《中国地质灾害与防治学报》2008,19(2):32-35

黄土塬区提灌工程保证了农业生产,却造成了地下水位大幅抬升,使得近年来黄土台缘滑坡不断发生。黄土滑坡一个普遍特征就是后缘发育地裂缝以及落水洞,使地表水（灌溉水以及降雨）直接灌入坡体,诱发了大量黄土滑坡。因此,地表水入渗对于黄土滑坡机理研究以及滑坡防治具有重要意义。文章基于对陕西泾阳南塬黄土滑坡的现场调查,对黄土台缘滑坡地表水入渗工程地质问题进行了初步分析,包括：①地表水入渗与落水洞形成机制;②地表水入渗途径及其与黄土滑坡发育过程的关系;③降雨因素对于黄土滑坡的影响程度。  相似文献   

Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics     

CV Ramana  U Becker  V Shutthanandan  CM Julien 《Geochemical transactions》2008,9(1):8

Molybdenum disulfide (MoS₂), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS₂ is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.  相似文献   

Composition and pre-metamorphic geodynamic setting of the ultrahigh-pressure metabasic rocks from Dabie Shan,E-China     

U. Altenberger  R. Schmid  R. Oberhänsli 《International Journal of Earth Sciences》2008,97(6):1301-1314

As part of the Yangtze plate, segments of the Dabie Shan terrane of Central China underwent ultra-high pressure metamorphism during Triassic subduction. We studied the geochemistry of the abundant eclogites to evaluate the nature of the protoliths and their geodynamic setting. Although some previous geochemical work exists, the analyses and interpretation herein are based on a new subdivision of the ultra-high pressure sequence into basement and cover units (Changpu and Ganghe Unit), revealing new and important results. In addition, eclogites of the so-called HP Unit south of the UHP units were studied. Whereas the large ion lithophile elements indicate postmagmatic, metasomatic changes of some samples, the high-field strength elements and the rare earth elements display original magmatic trends. The geochemical characteristics of the eclogites of the ultra-high pressure areas display a strong dependence on their “structural” and geographic position. The eclogites of the basement and the Changpu Unit indicate melt intrusion and extrusion in a continental rift system, i.e. during extensional tectonics. In contrast, the Ganghe Unit is characterized by a pronounced chemical homogeneity. The composition of the eclogites indicates generation from a mantle source highly influenced by slab-derived fluids. Those of the HP Unit show similar characteristics. Magmatism of the Ganghe and HP Unit probably occurred in a continental arc setting. A similar age for both units, geographically and/or tectonically separated, is possible. The geodynamic interpretation based on the geochemistry of the four units points to a Neoproterozoic scenario in which the protoliths of the HP and the cover units could have been of similar age and deposited in one evolving geological system. A rift-related larger-scale basin might have formed, e.g. a continental back-arc basin behind a magmatic arc after or simultaneous to sedimentation and magmatism in the magmatic arc. Alternatively, magmatism occurred in independent geodynamic settings, distinct in time and space. The units were juxtaposed during exhumation, after subduction to varying depths.  相似文献   

Sedimentary basin evolution: subsidence, salt dynamics, fluid flow and deformation     

U. Bayer  D. Gajewski  R. Littke 《International Journal of Earth Sciences》2008,97(5):883-886

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Illite crystallinity patterns in the Anti-Atlas of Morocco     

Geoffrey M. H. Ruiz  Urs Helg  François Negro  Thierry Adatte  Martin Burkhard 《Swiss Journal of Geoscience》2008,101(2):387-395

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Phosphorus removal in low alkalinity secondary effluent using alum     

R. J. Banu Ph.D.  K. U. Do Ph.D.  I. T. Yeom M.Sc. 《International Journal of Environmental Science and Technology》2008,5(1):93-98

The alkalinity plays an important role in phosphorus removal using coagulant. The dosage of coagulant in the low alkalinity wastewater is limited due to rapid pH changes. In the present study, a series of jar test was conducted using low alkalinity wastewater (50 mg/L) to evaluate the optimum pH, dosage and performance parameters (slow mixing and settling time) for the common coagulant alum. From the experiment, it was found that the dosage of coagulant and removal of phosphorus depend upon the pH of the wastewater after adding coagulant. The final optimum pH for efficient P removal was found to be within the range of 5.7–5.9. This range acts as an indicator and it is the maximum tolerable pH range for phosphorus removal for low alkalinity wastewater. The optimum time for slow mix and settling was found to be 20 min. The optimum mole ratio of alum to remove one mole of phosphorous was found to be 2.3. The alum coagulation at pH 7 produced effluent with the total residual phosphorus and reactive phosphorus content of 0.3 and 0.9 mg/L, respectively.  相似文献   

Low frequency flickering of TT arietis: Hard and soft X-ray emission region     

Altan Baykal  Ümit Kiziloğlu 《Astrophysics and Space Science》1996,246(1):29-38

Using archival ASCA observations of TT Arietis, X-ray energy spectra and power spectra of the intensity time series are presented for the first time. The energy spectra are well-fitted by a two continuum plasma emission model with temperatures 1 keV and 10 keV. A coherent feature at 0.643 mHz appeared in the power spectra during the observation.  相似文献   

The contact binary system YY Eri     

E. Budding  C-H. Kim  O. Demircan  Z. Müyesseroğlu  K. Saijo  T. Banks 《Astrophysics and Space Science》1996,246(2):229-242

Relatively new and unanalysed photometric data-sets of the contact binary system YY Eri are presented. The light curves have been analysed using information limit optimization techniques, and the Binary Maker program of Bradstreet (1992).Comparison of the results allows insight into determinacy questions affecting the W UMa type of light curve, which relates to our general understanding of contact binaries. A limiting contact configuration cannot be ruled out on the basis of empirical data-analysis alone.Very careful analysis of the photospheric flux distribution over the surface of the Sun may help establish appropriate values of the gravity brightening parameter for cool dwarf stars. At present, however, empirical photometric information on contact binaries is non-discriminatory: i.e. alternative cosmogonies can find alternative support from available evidence. The implication is then for more and better observational data to allow better real independent parameter determination.  相似文献   

Weak-contrast approximation of the elastic scattering matrix in anisotropic media     

Bjørn Ursin  Geir U. Haugen 《Pure and Applied Geophysics》1996,148(3-4):685-714

The plane-wave reflection and transmission coefficients at a plane interface between two anisotropic media constitute the elements of the elastic scattering matrix. For a 1-D anisotropic medium the eigenvector decomposition of the system matrix of the transformed elasto-dynamic equations is used to derive a general expression for the scattering matrix. Depending on the normalization of the eigenvectors, the expressions give scattering coefficients for amplitudes or for vertical energy flux.Computing the vertical slownesses and the corresponding polarizations, the eigenvector matrix and its inverse can be found. We give a simple formula for the inverse, regardless of the normalization of the eigenvectors. When the eigenvectors are normalized with respect to amplitudes of displacement (or velocity), the calculation of the scattering matrix for amplitudes is simplified.When the relative changes in all parameters are small, a weak-contrast approximation of the scattering matrix, based on the exactly determined polarization vectors in an average medium, is obtained. The same approximation is also derived directly from the transformed elasto-dynamic equations for a smooth vertically inhomogeneous medium, proving the consistency of the approximation.For monoclinic media, with the mirror symmetry plane parallel to the interface, the approximative scattering matrix is given in terms of analytic expressions for the non-normalized eigenvectors and vertical slownesses. For transversely isotropic media with a vertical axis of symmetry (VTI) and isotropic media, explicit solutions for the weak-contrast approximations of the scattering matrices have been obtained. The scattering matrix for amplitudes for isotropic media is well known. The scattering matrix for vertical energy flux may have applications in AVO analysis and inversion due to the reciprocity of the reflection coefficients for converted waves.Numerical examples for monoclinic and VTI media provide good agreement between the approximative and the exact reflection matrices. It is, however, expected that the approximations cannot be used when the symmetry properties of the two media are very different. This is because the approximation relies on a small relative contrast between the eigenvectors in the two media.Presented at the Workshop Meeting on Seismic Waves in Laterally Inhomogeneous Media, Castle of Trest, Czech Republic, May 22–27, 1995.  相似文献   

Neutron stars in the multidimensional einstein theory of gravitation     

U. Bleyer  L. Sh. Grigorian  H. F. Khachatrian 《Astrophysics》1996,39(4):359-369

The radius, mass, total number of baryons, and other parameters of static, spherically symmetric, superdense stars are calculated. A model with one Ricci-flat inner space of arbitrary dimensionality and the approximation p₁=?0.5ε + ap for additional components of the energy — momentum tensor are used (ε and ρ are the total energy density and the pressure of the stellar matter and a is a fitting parameter). In the case of white dwarfs, the results of the multidimensional theory do not depend on the dimensionality D of space-time for ?10 ? a ? 10 and coincide with the analogous data of the general theory of relativity (GTR). For neutron stars there is a dependence on D and a. For D>4, in particular, the greatest mass M_max of a neutron star as a function of a has a maximum at 3<a(D) ? 4, which exceeds the greatest mass M _max ⁰ =2.14 M_⊙ in the GTR. A comparison of theoretical results with observational data determines the allowable values of a. Data for PSR 1913 + 16 lead to 0.2 ≤ a ≤ 9.2 in the case of D=26, while the results of [P. C. Joss and S. A. Rappaport, Annu. Rev. Astron. Astrophys.,22, 537 (1984)] lead to the stricter limits 1 ≤ a ≤ 7.4.  相似文献