排序方式： 共有13条查询结果，搜索用时 15 毫秒
11.
对采自北极新奥尔松(Ny-lesund)一级海岸阶地上的海蚀凹槽沉积剖面进行沉积岩相学、同位素地球化学和元素地球化学研究,结果显示该剖面的70-118 cm段显著受到了海鸟粪沉积的影响,为含贝壳的海鸟粪土沉积层。该段粪土沉积层中大多数元素的浓度随深度表现出明显的波动特征,其中TOC、TN、Se、Sr、CaO、Pb、As、Zn等元素含量在深度剖面上表现出较为一致的垂向变化趋势。对粪土层的元素地球化学数据进行了聚类分析,结果表明在浓度剖面上具有较好协同关系的上述元素组合与海鸟粪有机质的输入密切相关,这些具有显著地球化学性质差异的元素共生组合是北极新奥尔松粪土沉积层的生物地球化学组合的标型特征,它们的含量变化主要受控于海鸟粪对沉积物的影响程度。海鸟粪土生物地球化学标型组合特征的识别为进一步研究该地区12-4 ka B.P.的海鸟生态系统和气候演化记录提供了科学基础。 相似文献
12.
将桩土系统划分为数量足够多的微元段,相邻微元桩段接触面处的环形凸面与土的相互作用采用单个Voigt体模拟,求得Voigt体的弹簧和黏壶系数。结合相邻微元桩段接触面上的应力平衡条件和位移连续条件,得到修正的阻抗函数递推法,桩身采用Rayleigh杆考虑桩身的横向惯性效应。结合桩底的边界条件,运用拉普拉斯变换和修正的阻抗函数递推法求得了平面应变条件下成层土中考虑桩周土竖向作用时大直径楔形桩桩顶复阻抗的解析解。通过与已有解对比,研究了桩周土竖向作用对桩顶复刚度和桩顶在瞬态激振下的速度响应的影响,并在低频域内详细分析了桩周土的竖向作用与桩土系统参数对桩顶复刚度的影响的耦合作用。 相似文献
13.
Successful design of soil liner and covers for landfills and waste impoundments involves selection of liner material and assessment
of chemical compatibility of the liner material. In this work locally available materials with different mineralogy have been
evaluated from the viewpoint of liner application. Many local soils may not meet the requirements of liner material; often
it is necessary to amend these soils with commercially available processed bentonite. Clay liners may be attacked by chemical
waste or leachate, concentrated organic chemicals can attack compacted clay effectively destroying the characteristics of
liner material. Thus the main aim of this work has been to assess the suitability of different types of locally available
materials for their potential use as liners for waste containment facilities. The materials studied are kaolinitic red earth,
illite and fly ash. Based on literature survey and experimental work in this laboratory, 20% by weight of bentonite has been
chosen for amending selected materials. Addition of 20% bentonite to selected liner material improved the hydraulic conductivity
and adsorption capacity of the amended mixture but, reduced the volume stability. To improve the volume stability of the amended
material and to have better resistance towards chemicals attack, stabilizing the amended mixture with 1% by weight of lime
has been considered. The relative advantages and disadvantages of four materials namely; red earth with 20% bentonite, illite
with 20% bentonite, fly ash with 20% bentonite and illite alone, stabilized with 1% by weight of lime were brought out. The
chemical compatibility of the materials to electrolyte solution (0.5 N NaCl), alkaline solution (0.5 N NaOH), acid (0.5 N
HCl) and organic fluid (CCl4) has been studied. The relative efficiency of the selected materials with selected pore fluids was compared. 相似文献