改性蒙脱石吸附Pb^2＋、Hg^2＋的实验研究   总被引：8，自引：0，他引：8  

王毅  王艺  王恩德 《岩石矿物学杂志》2001,20(4):565-567

对蒙脱石进行化学改性后生成的硫代蒙脱石热稳定性好，并且对金属离子Pb^2 、Hg^2 有很好的吸附性能，是一种处理污水中有害金属离子有效的矿物材料。  相似文献   

Ground Stabilization for foundation and excavation construction in Florida karst topography     

L. J. Almaleh  J. D. Grob  R. H. Gorny 《Environmental Geology》1993,22(4):308-313

The construction of additional facilities at the Florida Power Corporation's Crystal River Energy Complex required an extensive stabilization program to construct foundations for approximately one half mile of cooling towers. This paper presents an overview of the techniques and methods used in the construction of additional facilities at the Crystal River Generating Station. Excavations for intake and discharge structures were to be more than 20 ft below the water table. Cooling tower foundations were constructed on extensively solutioned Florida limerock located on the central Gulf Coast of Florida. Hybrid ground modification techniques were used to stabilize soft or loose soils and solution features in the underlying limerock, allowing mat and spread footing foundations to be used for most of the facility. The ground modification techniques were used to detect, collapse, densify, and fill solution features below the structure foundations. The bearing capacity after ground modification was verified by field load tests. Subsurface investigations indicated that sheet pile excavations with grouted seals were the optimal technique for cofferdam excavations in the limerock formation. Existing collapsed caverns were encountered during construction of the cofferdam for the intake structure and the adjacent discharge structure, requiring a fast-track design change, considerable field coordination, and daily modifications to accommodate the varied conditions encountered. Tied-back soldier pile cofferdam construction was combined with grouting, underwater excavation, and a massive, unreinforced, concrete tremie slab with grouted anchors, and installed off a barge to provide a dewatered excavation. This project involved the use of hybrid soil-rock anchors to anchor one of the largest continuous placement tremie seals installed in Florida. Other excavations used sheeting and grouting of the underlying limerock formation to provide a dewatered excavation. Ground modification techniques were used to treat a filled cavern discovered in the corner of one discharge structure. The entire construction of this facility was confined to a narrow work area by existing wetlands and the generating station discharge canal. Strict environmental restrictions required by the regulatory agencies to prevent impacts to the surrounding area were imposed on this project.  相似文献   

四阶矩准正态分布和三阶矩剪切近似的验证   总被引：1，自引：0，他引：1  

张强  胡隐樵 《大气科学》1994,18(4):396-404

本文利用近地面层大气湍流量的观测资料对四阶矩的准正态分布假定和三阶矩的剪切近似进行了实验验证。结果表明，四阶矩能够较好地符合准正态分布假定；三阶矩不仅完全满足剪切近似，甚至还可以对剪切程度进一步加强，并且得到了一系列剪切近似的加强修正系数。  相似文献   

Damping modification factors for SDOF systems subjected to near‐fault,far‐fault and artificial earthquakes     

George D. Hatzigeorgiou 《地震工程与结构动力学》2010,39(11):1239-1258

Damping modification factors (DMF) are used in modern seismic codes to adjust elastic response spectral values corresponding to 5% of viscous damping to other higher or lower damping levels. This paper presents a simple and effective procedure to estimate DMF for single‐degree‐of‐freedom systems. Empirical expressions are proposed for displacement, velocity and acceleration response spectra, where four types of soil conditions, from hard rock to soft soil are considered. This study also examines, for the first time, the influence of artificial earthquakes on DMF. Furthermore, natural near‐fault and far‐fault seismic ground motions are considered where it is testified that the fault distance has no impact on DMF. Finally, it confirms that, in contrast to the considerations of many seismic codes, DMF are strongly dependent on the period of structural vibration while there are significant problems of using the same modification factor to estimate maximum displacement, velocity and seismic forces. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

北京2008年奥运会开幕日云、降水特征及人工影响天气作业分析   总被引：4，自引：3，他引：1  

李宏宇  马建立  马永林  陶玥 《气候与环境研究》2011,16(2):175-187

2008年奥运会开幕日当天北京及周边地区出现了较强对流云团,尤其是西南和东北两个方向云体发展旺盛,并且向北京城区形成“合围”之势,给国家体育场内开幕式活动的顺利进行带来了极大威胁。根据天气实况,北京市有针对性地组织实施了大规模地面火箭人工消减雨作业。利用自动气象站雨量监测、雷达云和降水探测以及卫星资料反演的云特征参量,通过对奥运会开幕式活动期间云、降水主要特征及人工消减雨作业的物理响应分析,结果显示：2008年8月8日傍晚至夜间北京西南和东北部郊区(县)对流发展较强,19时（北京时间,下同）至23时降水集中分布于北京房山区与怀柔区、密云县一带。北部—东北部对流云团和雨带在向东北方向缓慢移出过程中曾出现西伸、南压现象,西南部对流云团在进入房山区后其主体移动缓慢,雨区向东偏北移动并威胁到城区和国家体育场,最后云团沿东南方向逐渐移出北京市。结合地面火箭作业的时间、空间分布,通过对目标区内自动气象站雨量、雷达回波探测和卫星资料反演的云、降水宏微观特征参量变化分析均表明,大规模和高强度的火箭引晶作业对抑制云、降水的形成和发展起到了一定作用。  相似文献   

用东海和南海潮汐资料修正全球海潮模型对中国及邻区重力场负荷计算的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

周江存  孙和平 《地震学报》2005,27(3):332-338

利用11个全球海潮模型和中国东海及南海近海潮汐资料,计算了海潮负荷对中国及邻区重力场的影响,进而讨论了用近海潮汐资料修正全球海潮模型对负荷结果的影响. 结果表明, 用近海潮汐资料修正全球海潮模型对沿海地区的负荷计算影响较大, 因此在计算海潮负荷对沿海台站的影响时, 必须顾及近海潮汐效应. 计算M2波海潮负荷时, 选择CSR4.0, FES02, GOT00, NAO99和ORI96海潮模型, 则对于内陆大部分台站负荷的近海效应在0.1times;10-8m/s2量级; 而计算O1波时, 如选择AG95或CSR3.0模型, 则在0.05times;10-8m/s2量级. 这说明模型中的各个潮波在我国沿海的准确性并不是一致的, 因此模型的选择是比较复杂的.   相似文献   

考虑场地类别的阻尼比修正系数研究   总被引：1，自引：0，他引：1  

蒋建  吕西林  周颖  蒋欢军 《地震工程与工程振动》2009,29(1)

阻尼比修正系数B用于调整临界阻尼比不同于0．05时的反应谱值,它对减震结构、隔振结构以及弹塑性体系的简化设计与分析具有重要意义。本文按照我国现行抗震规范规定的场地分类方法,分别应用四类场地共计136条地震记录,对阻尼比为0．05、0．1、0．2、0．3、0．4、0．5的弹性单自由度结构体系的相对位移反应谱、相对速度反应谱、绝对加速度反应谱进行计算分析,从定性到定量系统研究了地震作用下场地分类、阻尼比以及结构周期对相对位移反应谱阻尼比修正系数眈、相对速度反应谱阻尼比修正系数Bv和绝对加速度反应谱阻尼比修正系数口。的影响规律,结果表明：随着阻尼比的增大,场地分类对阻尼比修正系数的影响程度逐渐增大,其中场地条件对Ba的影响更加显著,然而数据分析表明,场地条件对阻尼比修正系数最小值的影响很小。在IV场地上,阻尼对长周期结构的减震效果明显优于其它三类场地。最后通过非线性回归分析,建立了与场地类别、结构周期以及阻尼比相关的阻尼比修正系数Ba、Bd、Bv的计算公式。这部分的结果可以应用于减震结构基于．胜能的抗震设计方法中。  相似文献   

拼合的准噶尔盆地基底: 基底火山岩Sr-Nd同位素证据   总被引：9，自引：2，他引：7       下载免费PDF全文

郑建平  吴晓智 《地球科学》2000,25(2):179-185

在详细岩相学、主元素和微量元素研究基础上, 报道了准噶尔盆地基底不同区块火山岩的Sr-Nd同位素和锆石颗粒年龄研究成果, 结合盆地周缘造山带古生代构造史、古生物、沉积建造、火山岩、侵入岩的综合研究成果, 表明准噶尔盆地基底可能由分属哈萨克斯坦板块、塔里木板块(?) 和西伯利亚板块刚性体外围的岛弧体系经构造软碰撞拼合而成, 它们又经历了块体拼合后的构造-岩浆热事件(如基性岩浆底侵作用) 的进一步改造和影响.   相似文献   

半导体多相光催化氧化技术在环境保护中的应用研究进展   总被引：2，自引：0，他引：2       下载免费PDF全文

罗菊仙  赵中一 《地球科学》2000,25(5):536-541

简单介绍了半导体多相光催化氧化的原理及其在降解污染物和环境保护中的应用和一些新型反应装置, 提出了提高光催化剂催化活性的方法, 讨论了影响光催化氧化反应速率的因素和提高光催化氧化反应速率的方法, 同时对光催化氧化技术今后的研究方向和工作重点提出了一些设想   相似文献   

Modeling of the Removal of Arsenic Species from Simulated Groundwater Containing As,Fe, and Mn: A Neural Network Based Approach     

Prasenjit Mondal  Bikash Mohanty  Chandrajit Balomajumder  Samir Saraswati 《洁净——土壤、空气、水》2012,40(3):285-289

The present paper deals with the modeling of the removal of total arsenic As(T), trivalent arsenic As(III), and pentavalent arsenic As(V) from synthetic solutions containing total arsenic (0.167–2.0 mg/L), Fe (0.9–2.7 mg/L), and Mn (0.2–0.6 mg/L) in a batch reactor using Fe impregnated granular activated charcoal (GAC‐Fe). Mass ratio of As(III) and As(V) in the solution was 1:1. Multi‐layer neural network (MLNN) has been used and full factorial design technique has been applied for the selection of input data set. The developed models are able to predict the adsorption of arsenic species with an error limit of ?0.3 to +1.7%. Combination of MLNN with design of experiment has been able to generalize the MLNN with less number of experimental points.  相似文献