半空间埋置动点源荷载问题的传递矩阵法     

周海林 《岩土工程技术》2004,18(2):55-58

引用了流体饱和两相多孔介质的动力控制方程分析半空间埋置动点源荷载问题的位移和变形。经过Laplace Hankel变换 ,控制方程化成常微分方程组。利用数学软件mathmatic对上述方程组求解 ,可以得到单层砂土的传递矩阵。分析过程中 ,假设在两层面上 ,位移与应力相互连续 ,可以借鉴有限元的思想进行耦合计算。这样就获得了在饱和砂土中施加竖向动荷载问题的Laplace Hankel变换解 ,其最终的解还需要通过Laplace Hankel逆变换得到  相似文献   

Dynamic response of partially sealed circular tunnel in viscoelastic saturated soil   总被引：1，自引：0，他引：1  

Kang-he Xie  Gan-bin Liu  Zu-yuan Shi 《Soil Dynamics and Earthquake Engineering》2004,24(12):1003-1011

Based on Biot's wave equation, dynamic response of a circular tunnel with partially sealed liner in viscoelastic saturated soil is investigated. By introducing two scalar potential functions, the analytical solutions of stresses, displacements and pore pressure induced by axisymmetric gradually applied step load are derived in Laplace transform domain. Numerical results are obtained by inverting Laplace transform presented by Durbin and used to analyze the influences of partial permeable property of boundary and viscoelastic damping coefficient of soil on dynamic response of the tunnel. It is shown that the attenuation of radial displacement appeared with the increase of viscoelastic damping coefficient of soil, and relative rigidity of liner and soil, and the influence of partial sealing property of boundary on stresses, displacements and pore pressure is remarkable. The available solutions of permeable and impermeable boundary conditions are only two extreme cases of this paper.  相似文献   

Analysis of Sediments and Soils by X-Ray Fluorescence Spectrometry Using Matrix Corrections Based on Fundamental Parameters   总被引：2，自引：0，他引：2  

Jacinta Enzweiler  Maria Aparecida Vendemiatto 《Geostandards and Geoanalytical Research》2004,28(1):103-112

Wavelength dispersive X-ray fluorescence spectrometry (WD-XRF) is widely used for the analysis of soils and sediments using well characterised procedures. However, difficulties can occur with samples such as unknowns containing small amounts of ore materials and samples collected from contaminated sites where trace elemental concentrations can exceed the concentration range for routine analysis. We studied the performance of a commercially available method, based on fundamental parameters (FP) to correct matrix effects. The spectrometer was originally calibrated with elemental or simple compound calibrants. Samples were analysed as pressed powder pellets. Eighteen sediment and soil reference materials, three of them with certified values for some of their constituents, were used to evaluate accuracy, by comparing results with recommended values and their standard deviations (RV ± 2s) or certified values and their confidence intervals (CV ± Cl). When results fell systematically outside these intervals, calibrations were refined with geochemical reference materials. The best agreement of results with recommended and certified values was obtained when the contents of H₂O and C in each sample were included as matrix constituents during calculations. The detection limits of trace elements tended to be relatively high, because the measuring conditions employed were not maximised for sensitivity. The main advantage of the method tested was that it enabled the analysis of samples with high concentrations of trace elements and the determination of elements such as F, Bi, Sb and W, which are not commonly included in quantitative XRF analysis of geological samples.  相似文献   

Triaxial stress state deep in orogenic belts: an example from Turkey     

T. Masuda  S. Nakayama  N. Kimura  K. Onodera  A. Okamoto 《Journal of Structural Geology》2004,26(12):2203-2209

A rare metachert pebble containing amphibole grains with microboudin structures in a wide range of orientations provides an opportunity to perform stress analysis in two orthogonal orientations on the foliation surface. The sample was analysed by the microboudin method to infer the triaxial stress state during microboudinage. Stress parameters proportional to the far-field differential stress were determined for sodic amphibole grains in the two orientations. The ratio of the stresses in the two orthogonal orientations (σ₁−σ₂)/(σ₁−σ₃) was calculated to be 0.64, indicating that σ₂ lies closer to the midpoint between σ₁ and σ₃ than to σ₃.  相似文献   

适用于大旋转角的三维基准转换的一种简便模型   总被引：33，自引：0，他引：33  

陈义  沈云中  刘大杰 《武汉大学学报(信息科学版)》2004,29(12):1101-1105

基于大角度的空间直角坐标转换，提出了以方向余弦为参数、适用于任何角度旋转的空间直角坐标转换的简明计算方法。  相似文献   

Scattering of plane SV waves by cylindrical canyons in saturated porous medium   总被引：4，自引：0，他引：4  

Li Weihua  Zhao Chenggang 《Soil Dynamics and Earthquake Engineering》2005,25(12):981-995

On the basis of Biot dynamic theory, an analytic solution of two-dimensional scattering and diffraction of plane SV waves by circular cylindrical canyons in a half space of saturated porous media is presented in this paper for the first time. The solution is obtained by employing the Fourier–Bessel series expansion technique. Parametric studies had been carried out, which includes: the angle of incidence, the frequency of the incident SV wave, the porosity of saturated porous medium and the stiffness and Poisson's ratio of the solid-skeleton. All the outcomes are useful for the seismic analysis of the surface topography conditions.  相似文献   

石墨炉原子吸收光谱法测定土壤样品中镉   总被引：5，自引：0，他引：5  

卞莉  曹萍 《吉林地质》2005,24(2):115-117

采用磷酸氢二铵作基体改进剂塞曼扣背景石墨炉原子吸收光谱法测定土壤样品中镉，方法检出限DL=0．012μg／g，精密度RSD在3．55％～7．33％，满足了土壤样品中镉测定的镉质量要求。  相似文献   

General expressions for internal deformation fields due to a dislocation source in a multilayered elastic half-space     

Yukitoshi Fukahata  Mitsuhiro Matsu'ura 《Geophysical Journal International》2005,161(2):507-521

  相似文献   

Direct Current Plasma Emission Spectrometric Determination of Major, Minor and Trace Elements in Microwave Oven Acid Leachates of Powdered Whole Coal Samples     

Sandro Fadda 《Geostandards and Geoanalytical Research》2005,29(1):143-156

Major concentrations of Al₂O₃, Fe₂O₃, MgO, CaO, Na₂O and K₂O, minor levels of TiO₂, P₂O₅ and thirty petrologically, geochemically and environmentally significant trace elements have been determined in microwave oven acid leachates of whole powdered coal samples by direct current plasma‐atomic emission spectrometry (DCP‐AES). A single sample preparation procedure was suitable for all the determinations with no additional dilution step for major elements solution. Dried samples (0.5 g) were treated in low‐pressure PFA digestion vessels with HF/HCl/HNO₃/HClO₄ acids to quantitatively extract the analytes from the bulk material, while leaving the major part of organic matrix as a residue. The major constituents of geological samples, in particular the easily ionised elements (EIEs) such as alkali and alkaline earths, may complicate the instrumental determinations in DCP‐AES because of differential enhancements of elemental emission intensities and stray light interferences. Taking account of these factors, the coal matrix is considered to have very low major oxide totals as compared to many other common geo‐environmental and related materials (rocks, sediments, soil, ashes etc.). The sample size employed here, while yielding a relatively concentrated solution to cover a wide range of elemental determinations, provided a sample matrix that significantly diminished interferences for DCP measurements. The need for closely matching the unknowns and calibrators was eliminated except for overall acidity and an excess quantity of caesium for EIE buffering. Calibration of the spectrometer was accomplished by simple aqueous single element solutions as high concentration calibrators in addition to a reagent blank as a low concentration calibrator. Two point working curves were established to allow for the maximum concentrations of each element expected in the unknowns. The precision of determinations under routine conditions as well as the reproducibility of the leaching and precision of instrumental measurements have been evaluated. Relative standard deviations (RSD) were of 1–2% for those elements whose concentrations in solid samples were well above the limits of quantification. Method detection limits in the buffered solutions were also evaluated. To evaluate the accuracy of the microwave oven‐DCP method a suite of eight certified coal reference materials of differing rank, were analysed with good agreement with the certified and/or available published data. Results are presented for the uncertified major oxides in the AR series reference materials.  相似文献   

关于薄壁金刚石钻头胎体性能的探讨          下载免费PDF全文

王生福 《探矿工程》2005,32(11):57-58

对薄壁金刚石钻头胎体进行了性能分析和配方设计探讨，尤其根据被钻切介质对钻头胎体性能的要求作了较详细的分析，从理论分析结合实践经验筛选出了钻切建筑石材和各种钢筋砼的钻头胎体配方，在生产中满足了钻头工作条件的要求。  相似文献