弹性波的三维有限元模拟

本文讨论了弹性波瞬态传播问题的三维有限元计算方法及当前存在的实际困难.针对要求计算机内存大和计算时间长的问题,采取了改进措施.由于采用了集中质量矩阵和修正的中心差分时间积分显格式相结合的方法,可以使计算机内存和计算时间大为减少;由于采用结点定位法,最适合用于目前发展的并行计算机系统,可使计算速度大大增快;还采用了有效激发震源法,有效激发区是随时间步进的增加而逐步增大,这不仅能节省计算时间,而且使波场的传播过程一目了然,本文计算了由两种介质组成的三维楔形问题,得到若干典型剖面的瞬时波场图及随时间变化的合成地震图.     

Weathering and climate change since l820 AD in Hoh Xil, Qinghai-Xizang Plateau, China——Evidence from element geochemistry of lake sediments of Gulug Co Lake

Element geochemistry of lake sediments has been widely used to detect climate change because element composition and ratios can reflect the weathering degree in the source area. Given the dement composition of lake sediments from Gulug Co Lake, Hoh Xil, Qing- hai-Xizang Plateau, chemical index of alteration （CIA）, index of composition variability （ICV） and other element ratios have been used to establish the weathering sequence of this area since 1820 AD. The weathering is so weak that the element composition change is more sensitive to climate change and autochthonous processes. From 1820 to 1984 AD, there were two drier periods with a wetter interval from 1870 to 1945 AD. After 1984 the weather showed a tendency of becoming wet.     

Determination of potential hazardous elements in Can coals （Canakkale- Turkey）-I

It is known that the increasing use of coal as an energy source led to the growing environmental and health problems. But comprehensive knowledge of coal quality parameters may help to reduce some of these problems. The Canakkale-Can coalfield is located in the western part of Turkey, whose reserves are estimated at 69.3 billion tons, mainly used in the industry in the neighboring areas, specifically for the Can Thermal Power Plant. The aim of this study is to determine the coal quality parameters and examine the origin and distributions of potentially toxic trace elements in lignite which may produce environmental and health hazards in the area. The coal samples were collected from different parts of the coalfield in Can. Proximate and ultimate analyses, sulfur form analyses, X-ray powder diffraction （XRD）, inductively coupled plasma-mass spectrometry （ICP-MS）, and scanning electron microscopy （SEM） were performed on those samples to determine the geochemical profile of hazardous elements.     

Elements pollution in the extremely high tumor risk residents in Chaoshan littoral, southern China

Background ＆ aim： To investigate and analyze the elements pollution in the extremely high tumor risks residents in the Chaoshan littoral, southern China. Methods： 19 elements including Cr, Mn, Ni, Sr, Pb, Zn, Co, Sn, Th, Tl, Se, Hg, Cu, Mo, Cd, Sb, U, Ge, As, and Al were measured from 145 hair samples of residents from the high-risk Nanao Island （mortality of cancer 173-156/106 in recent 30 years）, Shantou high-risk village （mortality of cancer 230.4/106 in recent three years）, and two controls Shanwei （mortality of cancer 32/106 in 1970s） and Meizhou Hakka （incidence of cancer 103/106 ） using AAS, AFS, ICP-MS methods collaborated with Beijing University. And 21 samples of water, 18 samples office from the Nanao Island, Shantou high-risk village, and other low-risk controls were measured using the same methods. Results： The element analysis showed that levels of CD, PB in the Shantou high-risk village were the highest, Hg, MN, SR, SB, TH, U on the Nanao Island were the highest in hairs. Conclusions： It is indicated that there occurred elements pollution among the local high-risk population.     

Effects of low molecular weight organic acids on sorption and desorption behavior of p-chlorophenol by yellow earth

Low molecular weight organic acids （LMWOAs） are important components of root exudates. They play an important role in immobilizing and remobilizing contaminants in rhizospheric soil. Effects of four LMWOAs on the sorption and desorption behavior of p-chlorophenol by yellow earth was studied in batch mode. The results showed that the previous application of LMWOAs to enhanced adsorption capacity of p-chlorophenol of the soil in the order of maleic acid〉malic acid〉oxalic acid〉citric acid. However, when LMWOAs were applied to soil where p-chlorophenol had been previously adsorbed, substantial p-chlorophenol was desorbed from soil by oxalic acid, whereas citric acid, malic acid and maleic acid didn＇t desorb as much p-chlorophenol from soil as deionized water.     

用于砾石夹层钻进的新型PDC钻头的研制与使用

无压浸渍工艺生产的PDC石油钻头钻遇砾石夹层不适应。根据砾石夹层砾石坚硬、软硬互层、非均质、研磨性强的特点，研究了新型PDC钻头，在钻头结构上主要采取外抛内锥带辅助切削齿的结构形式，在复合片上主要采用非平面结合方式，即采用双向多条直槽非平面结合。按此方案设计与生产了3只钻头，分别在3口井试用，直接钻穿砾石夹层馆陶组地层井段，钻井效率提高26%，突破了砾石夹层钻进不能使用PDC钻头的禁区。     

Discrete numerical modelling of rockfill dams

The aim of this study is to obtain quantitative information on the behaviour of rockfill used in embankment dams, and particularly on the influence of block breakage on the displacement field, from a numerical analysis using the Distinct element method. A methodology is set up to define the resistance of the 2D particles so that the same probability of breaking blocks may be reproduced as in a 3D material. The model uses the discrete element code PFC^2D (Itasca Consulting Group Inc., PFC2D (Particle Flow Code in Two Dimensions), Version 3.0, 2002) and considers breakable clusters of 2D balls. The different parameters are determined from experimental data obtained from laboratory tests performed on rock blocks. The model is validated by comparing the results of the simulation of shearing tests with actual triaxial tests on rockfill material published in the literature. The numerical analysis of block crushing in an actual dam is proposed in the last part of this paper. Copyright © 2006 John Wiley & Sons, Ltd.     

Indium Enrichment in the Meng'entaolegai Ag-Pb-Zn Deposit, Inner Mongolia, China

Abstract. The Meng'entaolegai In-rich Ag-Pb-Zn deposit is located in the eastern part of Inner Mongolia. It is one of the In-richest deposits in China. Large amounts of quartz and sulfide minerals constitute a hydrothermal quartz-sulfide vein deposit within a Hercynian acidic granite massif, which occupies an area of about 400 km². Thirty-six orebodies, controlled strictly by the E-W trend faults, are found in the orefield of 6 km in length from east to west and 200 to 1,000 m in width from south to north. The ore minerals are mainly galena, sphalerite and pyrite, and subordinate chalcopyrite, arsenopyrite, cassiterite and stannite with many Ag-minerals. The gangue minerals are mainly quartz, calcite, sericite and chlorite. Economic components of the deposit are dominated by Pb andZn (reserves of Pb and Zn are 0.17 Mt and 0.37 Mt, and their grades are 1 % and 2.3 %, respectively), with Ag, Sn, In and Cd (1,800 t Ag, >2,000 t Sn, >500 t In and 1,800 t Cd) as by-products. Indium is highly enriched in ores and its contents are 9 to 295 ppm in ores and 85 to 2,660 ppm in sphalerite. Analytical results show that the ore-forming fluid of this deposit contains 0.8–3.5 ppm In and 4–36 ppm Sn, and the two elements show a very good positive correlation with a correlation coefficient of 0.8672, while the correlation between In and Zn in the ore-forming fluids, with a correlation coefficient of 0.5723, is not as good as that between In and Sn. This indicates that indium has an affinity with tin in the ore-forming fluids. The authors think that this is probably the main reason why those In-rich deposits spread over the world are simultaneously enriched in tin.     

Naturally acidic and metalliferous waters at unmined volcanogenic massive sulfide deposits in the Bonnifield mining district, Alaska Range, east-central Alaska

The Bonnifield district hosts 26 tmmined volcanogenic massive sulfide （VMS） occurrences. Environmental geochemical samples of water and stream sediment were collected at several occurrences, concentrating on the two best-exposed and largest deposits, Red Mountain （RM） and Sheep Creek （SC）. Limited samples were also collected at the poorly exposed WTF deposit. The deposits are Late Devonian to Early Mississippian, and are hosted by felsic metavolcanic and carbonaceous schist members of the Totatlanika Schist or Keevy Peak Fm. Spring and stream waters at RM and SC have pH values commonly 〈3.5 （as low as 2.4 at RM and 2.5 at SC）, high conductivity （up to 11000 μS/cm）, and very high （Is to 100s mg/L） dissolved contents of Al, Cd, Co, Cu, Fe, Ni, and Pb. Waters at RM are characterized by extremely high REE contents （summed REE median 3200 μg/L, n=33）. At both RM and SC, pyrite oxidation and dissolution produce low pH waters that interact with and dissolve bedrock minerals, resulting in acidic, metal-laden, naturally degraded streams that are mostly devoid of aquatic life. Ferricrete is common. In contrast, WTF barely produces a surficial environmental footprint, mostly due to topography and relief. RM and SC are well exposed in the areas of relatively high relief, and both exhibit extensive areas of quartz-sericite-pyrite-alteration. While WTF shares many of the same deposit-and alteration characteristics, it is concealed by tundra in a large, nearly flat area. Surface water at WTF is absent and outcrops are sparse. Even though WTF is roughly the same size as Red Mountain （both around 3 million tonnes） and has similar base- and precious-metal grades, the surficial geochemical manifestation of WTF is minimal. However, exposure through mining of the altered, mineralized rock at WTF potentially could initiate the same processes of pyrite oxidation, acid generation, and mineral dissolution that are observed naturally at RM and SC.