Analytical and numerical analyses of the load‐bearing capacity of retaining walls laterally supported at both ends

This paper investigates the load‐bearing capacity of a perfectly smooth retaining wall laterally supported at both ends assuming that the wall fails by the development of three plastic hinges. The study considers the case of a cohesionless elastic–perfectly plastic backfill with a Mohr–Coulomb yield criterion and an associative flow rule in drained conditions. A kinematically admissible soil–structure failure mechanism is proposed and compared with the conventional solutions and with results from a numerical finite element modelling. The study shows that the proposed solution and the numerical solution are in good agreement. These solutions are found to be much more favourable for the wall than the conventional solutions. Copyright © 2010 John Wiley & Sons, Ltd.     

过去20年矿床事业发展的概略回顾

文章概略回顾了过去20年在找矿和成矿理论研究方面获得的若干重要成就。指出这一阶段虽在一些国家存在矿业不景气，但找矿进展，特别是金、铜矿床、仍很出色。矿业中国都强调了超大型矿床的重要性。在成矿理论方面，主要就多样复杂的海底成矿，三大巨型成矿域，成矿模式，中酸性岩浆岩及有关成矿作用，层控矿床，同位素、微量元素及气液包裹体运用于成矿等问题的研究历史作了回顾。     

白城市水稻种植区土壤的地球化学特征与水稻产量的相关性研究

吉林省白城市水稻种植区土壤的地球化学特征研究表明，土壤中的SiO2,TiO2,Al2O3,FeO,MnO和P2O5等主要元素的含量与水稻产量具有正相关性，而CaO和MgO等主要元素的含量与水稻产量呈负相关性。土壤中的稀土元素含量和水稻产量呈正相关性。     

山东淄博地区上寒武统沉积地球化学特征及其层序地层学意义

根据微量元素和稳定同位素的特征可以推断古盐度、古水温和古水深 ,恢复古沉积环境 ,并判断海平面的相对变化。对淄博地区上寒武统微量元素Sr、Ba、V、Ni和氧 碳同位素的研究结果表明其属于稳定的浅海环境 ,微量元素和氧 碳同位素的变化趋势与海平面的波动有一定的对应关系 ,而且从地球化学方面为层序地层的划分提供了依据。研究结果也表明 ,由于沉积地球化学特征的复杂性 ,不能简单地用一种因素来分析。     

Stevns Klint Fish Clay (FC-1): Preparation of, and Preliminary Results for, a Candidate Reference Material

The collapse of a section of the cliff at Stevns Klint, Denmark in 1986 provided a unique opportunity to collect about 50 kg of Fish Clay representing the Cretaceous-Tertiary (K-T) boundary layer. In this paper, details of the preparation of this sample are presented, together with preliminary analytical results to support the development of this sample as a reference material, particularly for the determination of iridium and the other platinum-group elements in clays and sediments associated with K-T boundary studies and in other environmental samples collected to study the effects of automobile exhaust catalysts.     

Determination of Platinum-Group Elements and Forty Two Other Elements in Two Candidate Danish Cretaceous-Tertiary Boundary Clay Reference Materials by INAA, ENAA and RNAA

Ruthenium, rhodium, palladium, osmium, iridium and platinum (PGEs) and forty two other elements in two candidate geological Cretaceous-Tertiary boundary clay reference materials taken from the Fish Clay, Stevns Klint, Denmark, were determined by a combination of neutron activation analysis (NAA) consisting of instrumental, epithermal and radiochemical NAA with or without nickel sulfide fire assay preconcentration. The accuracy of the experimental values was assessed by the comparative analysis of the certified reference materials.     

Coupling Size-Exclusion Chromatography and ICP-MS to Investigate the Speciation of Platinum-Group Elements in Environmental Samples

The applicability of size-exclusion chromatography (SEC) coupled online with a high resolution ICP-MS (HR-ICP-MS) to investigate the speciation of the platinum-group elements (PGE), Rh, Pd and Pt, was evaluated. Experiments were carried out to determine the efficiency of different hydrophilic and hydrophobic size-exclusion gel materials to select the optimal eluent in respect of resolution, recovery, reproducibility and limit of detection. The suitability of HR-ICP-MS as a reliable detection instrument at low pg ml⁻¹ levels was investigated by examining possible mass interferences with Rh, Pd and Pt. Laboratory experiments demonstrated the interaction and capability of forming complexes of humic substances with PGE, demonstrating the potential role of these ubiquitous natural substances in the mobilisation of PGE in the environment.     

Neutron Activation Analysis Applied to the Determination of Heavy Metals and Other Trace Elements in Sediments from Sepetiba Bay (RJ), Brazil

In this work, instrumental neutron activation analysis (INAA) was applied to the determination of the elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Nd, Rb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn in twenty eight bottom sediment samples from Sepetiba Bay, Rio de Janeiro, Brazil. With the concentration data obtained, contour maps were prepared, by using Kriging method, to show the spatial distribution of the studied elements in the Bay. The elements Co, Cr, Cs, Fe, Sc, Ta and Zn showed similar behaviour in the sediments, with higher concentrations along the northern coast of the bay, where the fluvial water inputs are concentrated. The distribution of U, rare earth elements and Ba in the Bay indicates that these elements are not deposited as contaminants.     

Soil geochemical prospecting for gold at Marrancos (Northern Portugual)

This paper discusses some geochemical mapping techniques and their effectiveness in detecting of gold and its pathfinder's geochemical anomalies. The study area (Marrancos area) is situated in Northern Portugal. Gold occurs in a quartz breccia with pyrite and arsenopyrite hosted by metamorphic rocks (hornfels) and it is present in these two sulphide minerals as inclusions or disseminated in the crystal lattice. In this area, the geochemical anomalies obtained by isoconcentration mapping of single elements were difficult to interpret. The use of alternative geochemical mapping such as multielement halos (additive halos) proved to be effective in the definition of Au, As, Bi, Sb, Te and Se secondary geochemical signature.     

Effect of widespread severely acidic soils on spatial features and abundance of trace elements in streams

In the coastal area of western Finland, a large number of streams are strongly acidic and contaminated with metals. The reason for this is not historical and present industrial, mining and urban activities, but a current high rate of weathering and leaching of widespread acid sulphate soils (pH 2.5–4.0) developed in artificially drained Holocene marine and lacustrine sulphide-bearing sediments. Evaluation of existing hydro- and geochemical field and experimental data revealed that: (1) cobalt, Ni and Zn are extensively leached from the acid sulphate soils and thus exist abundantly in streams affected by such soils, (2) copper and Tl are also leached abundantly from the acid sulphate soils, although not to the same extent as are Co, Ni and Zn, (3) vanadium is in general depleted and Cr only weakly enriched in streams draining ‘the average acid sulphate soil’, but they increase substantially in severely acidic streams in catchments underlain with particularly acidic soil, (4) arsenic and Pb are not leached more abundantly from the acid sulphate soils than from the common types of soils and sediments (till, glaciofluvial deposits, peat) resulting in aquatic abundance and distribution patterns unrelated to the acid sulphate soil occurrences.