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991.
A new analytical solution to axisymmetric Biot's consolidation of a finite soil layer 总被引:1,自引:0,他引:1
A new analytical method is presented to study the axisymmetric Biot's consolidation of a finite soil layer. Starting from the governing equations of axisymmetric Blot's consolidation, and based on the property of Laplace transform, the relation of basic variables for a point of a finite soil layer is established between the ground surface (z= 0) and the depth z in the Laplace and Hankel transform domains. Combined with the boundary conditions of the finite soil layer, the analytical solution of any point in the transform domain can be obtained. The actual solution in the physical domain can be obtained by inverse Laplace and Hankel transforms. A numerical analysis for the axisymmetric consolidation of a finite soil layer is carried out. 相似文献
992.
993.
无公害蔬菜、灌溉水、种植土壤中Pb、As、Cd、Cr的测定 总被引:1,自引:0,他引:1
采用原子吸收光谱法测定了广西区内几个无公害生产基地土壤、蔬菜、水样中Pb、As、Cd、Cr的含量,RSD<7%,回收率在94%-110%之间。用本法测定GBW 08302土壤标准物质,测得值与推荐值基本一致。 相似文献
994.
V. Balaram 《Accreditation and quality assurance》2000,5(8):325-330
Under an international collaborative certification programme, two new Polish soil reference materials, PL-1 (loess) and BPGM-1
(sandy loam soil), were analysed for 34 trace elements including all the rare earth elements using the acid decomposition
method and inductively coupled plasma - mass spectrometry (ICP-MS). After the certification by the organisers, the analytical
data obtained at our institute were compared with the certified data. 'Z-score' values calculated for individual trace elements
helped in the assessment of the quality of the data. While the majority of the data obtained on ICP-MS was very precise and
accurate, some of the data especially for elements such as Zr, Hf and Nb suffered from incomplete dissolution of the sample
and spectroscopic interferences. For some trace elements, certified data are not available for comparison. These features
together with the usefulness of interlaboratory collaborative programmes and ICP-MS for the certification of soil reference
materials are discussed.
Received: 6 August 1999 / Accepted: 28 February 2000 相似文献
995.
土壤淋溶柱色谱中有机调节剂对保留的影响 总被引:1,自引:0,他引:1
摘要:系统考察了55种非离子型化合物(包括11个氯代苯类、14个烷基苯类、22个多苯和多环芳烃类化合物、8个农药)在土壤淋溶柱色谱和较宽的淋洗剂(甲醇-水)组成范围内容量因子(k')与甲醇体积分数(ψ)的关系。用自制加压装柱机将标准土壤干法装填成10mmi.d.×100mm的液相色谱柱,ψ=00.80的等度淋洗剂的流速1mL·min-1,柱温(25.0±0.1)℃,用UV检测器在线检测。实验表明,logk'=logkw+aψ+bψ2和logk'=logkw-Sψ两式均可以用来描述保留规律,但后者因其计算简 相似文献
996.
997.
ICP-MS对土壤样品中有效硼的测定 总被引:8,自引:0,他引:8
文章建立了一种用ICP-MS测定土壤中有效硼(B)的方法。与常规检测方法相比, 该方法无须过滤,避免了样品的沾污。并简便快捷, 具备良好的精密度和准确度。方法检出限为0.009 ng·g-1, 相对标准偏差为2.66%, 回收率为93.0%~102.0%。 相似文献
998.
地下衬砌结构经常会受到内部动荷载的作用,内荷载引起的衬砌结构的动应力集中备受关注。采用Laplace变换和波函数展开法,对半空间饱和土中均布突加荷载作用下圆柱形衬砌结构的动力响应进行了研究。对以大半径凸圆弧来近似半空间表面,将半空间饱和土中的波动方程展开成无穷级数的形式,应用Graff加法公式进行坐标变换,根据连续条件和边界条件,确定波函数展开式中的未知系数,求得了半空间饱和土中均布突加荷载作用下圆柱形衬砌的动力响应解答,讨论了衬砌埋深对圆柱形衬砌动力响应的影响。该问题的求解,为地下结构的动力分析提供了一种有效方法。 相似文献
999.
A Fractal Approach to Model Soil Structure and to Calculate Thermal Conductivity of Soils 总被引:3,自引:0,他引:3
Heat transport in soils depends on the spatial arrangement of solids, ice, air and water. In this study, we present a modified fractal approach to model the pore structure of soils and to describe its influence on the thermal conductivity. Three different fractal generators were sequentially applied to characterize a wide range of particle- and pore-size distributions. The given porosity and particle-size distribution of a clay, clay loam, silt loam and loamy sand were successfully modeled. The thermal conductivity of the fractal soil model was calculated using a network of resistors. We applied a renormalization approach to include the effects of smaller scale structures. The predictions were compared with the empirical Johansen' model (Johansen, 1975), that postulates a simple linear relationship between ice content and thermal conductivity. For high ice-saturated conditions, the calculated thermal conductivity agrees well with the empirical model. To describe partial ice saturation, we assumed that some pores were coated by ice films enclosing the air-filled center. In addition, we introduced a reduced heat exchange coefficient of the particles for unsaturated conditions. The ice-saturated and -unsaturated thermal conductivity calculated with this approach was very similar to that estimated by the empirical model. The variation of the thermal conductivities for different spatial arrangements of pores and particles in the prefractals were determined. Extreme values deviate more than 50% from the mean values. 相似文献
1000.