高粘度非牛顿模型材料流变性能的实验测定

本文介绍了一种高粘度非牛顿模型材料流变性能的实验测定原理和方法。此法不仅可以得到材料的表观剪应变速率和非牛顿剪应变速率,还可以得到流变指数、应力指数和表观粘度。采用夹心式流变仪对M503模型材料进行了试验测定。M503是一种聚合物模型材料,由橡胶腻子XM-50(一种黑色密封材料)与滑石粉按重量1:1混炼而成。实验结果表明:M503是一种假塑性材料,当非牛顿剪应变速率控制在7.52-105.56×10-5s-1范围时,其应力指数n变化范围为1.15-3.33,表观粘度变化范围为4.69-0.99×107Pa·s。      

氮掺杂碳材料活化过硫酸盐降解4-氯苯酚

为了进一步研究氮掺杂碳材料活化过硫酸盐降解4-氯苯酚的方法,首先以廉价易得的废弃工业糖浆作为碳源,以氨水作为氮源,利用溶胶-凝胶法合成了3种氮掺杂碳材料（NC-700,NC-800和NC-900）,并利用扫描电子显微镜（SEM）、X射线衍射（XRD）、拉曼光谱（Raman）、X射线光电子能谱（XPS）等技术对氮掺杂碳材料进行表征分析;然后考察了NC-800投加量、过硫酸盐（PDS）投加量和初始pH等因素对4-氯苯酚去除率的影响,并进行了电子自旋共振（ESR）和自由基淬灭实验。结果表明：3种材料均可有效活化PDS降解4-氯苯酚,其中NC-800活化PDS去除4-氯苯酚效率最高;当NC-800投加量为100 mg/L、PDS投加量为5 mmol/L时,反应30 min后,50 mg/L的4-氯苯酚的总去除率达99.10%;初始pH对4-氯苯酚去除率无明显影响;NC-800活化过硫酸盐降解4-氯苯酚遵循非自由基途径,单线态氧为降解4-氯苯酚的活性物质。循环使用实验证明NC-800具有一定的稳定性,4次循环使用后,4-氯苯酚去除率仍可达到73.80%。     

火山岩型铀矿床的基本特征、研究进展与展望

火山岩型铀矿床主要分布在环太平洋带、阿尔卑斯-喜马拉雅山带、俄罗斯西伯利亚地台南部,形成于白垩纪、古近纪和新近纪等三个时期。其形成过程主要包括铀从源岩中萃取出、热液流体的运输、以及物理化学环境的变化导致铀的沉淀。铀的源岩一般是中酸性-酸性岩石,通常呈碱性、准铝质至过铝质,富硅质、富钾、贫钙,富集U、F、Nb、Ta、Zr、Th和Rb等元素,而亏损Mg、Fe、Ti、P、Ba、Sr、La和Eu等元素;与之有关的火山岩和次火山岩多数显示出A型花岗岩特征。铀通常赋存于副矿物或火山玻璃中,因此,铀源岩发生蚀变、副矿物发生蜕晶化是成矿物质释放的关键。火山岩型铀矿床中铀主要以碳酸盐和氟络合物离子形式迁移,铀的迁移形式对其沉淀机制有着重要影响。成矿流体通常是大气降水和岩浆水的混合,成矿温度集中在100～350℃、盐度一般小于15%NaCleqv。铀沉淀机制主要包括还原作用、pH值升高和沸腾作用。火山岩型铀矿床常伴生Mo、Be、Ag、Cu、Pb、Zn、Hg和F等元素。未来火山岩型铀矿成因机制的研究应加强成矿物质来源、铀与伴生元素成因关系研究,这不仅有助于提高对火山岩型铀矿床成矿过程的认识,也可为勘查找矿工作提供理论帮助。     

深厚吹填粉细砂地基加固试验研究

结合上海某深水港集装箱堆场地基加固工程,基于深厚吹填粉细砂的工程特性,通过对无填料振冲挤密法加固的有效性和工艺参数进行现场试验研究,对加固前后的土体变形、超静孔压变化、工艺参数和加固效果等进行了分析和讨论。结果表明,采用无填料振冲挤密法可以加固深层土体、增加粉细砂的密实度,有效消除不均匀沉降和液化危害,效果显著,并拓宽了振冲法的应用范围,可为在类似地基处理中的推广提供参考依据和成功经验。     

重庆大巴山超大型陶粒页岩矿产资源的发现与研究

页岩陶粒是一种以具有自膨胀性能的页岩或板岩为唯一原料加工制备的保温隔热矿物功能材料和轻质多孔基础材料.在介绍重庆大巴山超大型陶粒页岩矿产资源地质特征基础上,采用多种现代检测技术和与国内同类原料对比方法,研究了代表性陶粒页岩和生产试验样品的矿物材料学特征,结果表明:重庆大巴山城口—巫溪是优质陶粒页岩矿产资源的集中分布区,...     

Effect of infill materials on the performance of geocell reinforced soft clay beds

The present study deals with model plate load tests conducted on geocell reinforced soft clay beds to evaluate the effect of infill materials on the performance of the geocell. Commercially available Neoweb geocells are used in the study. Three different infill materials namely aggregate, sand and local red soil were used in the study. The load carrying capacity of the geocell reinforced bed (as compared to an unreinforced bed) was found to be increased by 13 times for the aggregate infill, 11 times for the sand infill and 10 times for the red soil infill. Similarly the reduction in the settlement was in the order of 78%, 73% and 70% aggregate, sand and the red soil infill materials respectively. Results suggest that the performance of the geocell was not heavily influenced by the infill materials. Further, numerical simulations were carried out using FLAC^2D to validate the experimental findings. The results from numerical studies are in reasonably good agreement with the experimental findings. The outcome of this work is successfully implemented in the construction of the geocell foundation to support a 3 m high embankment in the settled red mud in Lanjighar (Orissa) in India.     

黄河、长江泥沙特性对比分析*

通过对黄河、长江泥沙的粒度分析、矿物分析及石英包裹体分析,揭示了两大河流泥沙的差异性。黄河悬沙粗于长江而底沙比长江为细。重矿物组合中,黄河泥沙黑云母含量远高于长江,粘土矿物中蒙脱石含量约比长江多一倍。反映了两大河流水动力条件及泥沙源区的环境差异。石英包裹体分析,更反映了两大河流泥沙源区的成因环境,为区分河流泥沙来源提供了一种新的方法。     

Non‐linear analysis of shear band formation in sand

The paper investigates the incipience of shear band with an incrementally non‐linear constitutive equation. Necessary conditions for the emergence of shear band are derived. The lower bound solution is obtained by taking the strain rate inside and outside the shear band into consideration. Numerical results of localized bifurcation for general stress and strain are presented and compared with experiments. In the principal stress space, the stresses at the onset of shear band form a surface, which is partially enclosed by the failure surface for homogeneous straining. The significance of the analysis for identification of the material parameters and verification of the constitutive model against experiments is discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Performance of displacement finite elements for modelling incompressible materials

It is well established that severe numerical difficulties may arise when the displacement finite element method is used to analyse the behaviour of incompressible solids and this is particularly true for axisymmetric problems. These numerical difficulties are caused by excessive kinematic constraints and are reflected by strong oscillations in the calculated stress distribution and overestimations of collapse loads. The purpose of this paper is to present new displacement finite element formulations which are particularly suitable for axisymmetric analysis of incompressible materials. A direct comparison is made of the performance of various displacement finite elements in the analysis of elastic or plastic incompressible materials under axisymmetric loading conditions. Particular attention is focused on the performance of various axisymmetric displacement elements in predicting the stress field of incompressible or nearly incompressible materials. Copyright © 2000 John Wiley & Sons, Ltd.     

厦门西海域拟疏浚沉积物中重金属含量及潜在生态危害评价

报道了厦门西海域拟疏浚沉积物中的重金属含量水平及分布,并对其污染状况进行了潜在生态危害评价,为进一步开展疏浚物去污染技术研究提供了科学依据.研究结果表明：与其他海域的相比,马銮湾及其湾口外、筼筜湖的Cd、Hg、Cr、Zn含量较高.综合来看,厦门西海域拟疏浚沉积物重金属含量不很高（RI＜150）,属于轻微生态危害.但东渡码头外的X4站、马銮湾M2站沉积物中的Cd,及马銮湾M2站和筼筜湖Y2站沉积物中的Hg含量（40≤Er ＜80）都达到中等生态危害程度.