Electrokinetic potentials of mineral oxides and calcium carbonate in artificial seawater

Electroacoustic method was used to measure the zeta potentials of mineral oxides and calcium carbonate in artificial sea water (pH 8), and the following values were obtained: synthetic hematite: 0.87 mV; goethite: 1.01 mV; fumed silica: -3.56 mV; quartz: -1.38 mV; calcium carbonate: 1.91 mV. The absolute values of the zeta potentials obtained in the present study are substantially lower than the zeta potentials in seawater reported by other authors. Our results indicate that the effect of electrostatic repulsion in the interactions between the particles of these materials in seawater is negligible.     

Assessment and impact of microbial fecal pollution and human enteric pathogens in a coastal community

The goals of this study were to assess watersheds impacted by high densities of OSDS (onsite sewage disposal systems) for evidence of fecal contamination and evaluate the occurrence of human pathogens in coastal waters off west Florida. Eleven stations (representing six watersheds) were intensively sampled for microbial indicators of fecal pollution (fecal coliform bacteria, enterococci, Clostridium perfringens and coliphage) and the human enteric pathogens, Cryptosporidium, Giardia, and enteroviruses during the summer rainy season (May-September 1996). Levels of all indicators ranged between < 5 and > 4000 CFU/100 ml. Cryptosporidium and Giardia were detected infrequently (6.8% and 2.3% of samples tested positive, respectively). Conversely, infectious enteroviruses were detected at low levels in 5 of the 6 watersheds sampled. Using cluster analysis, sites were grouped into two categories, high and low risks, based on combined levels of indicators. These results suggest that stations of highest pollution risk were located within areas of high OSDS densities. Furthermore, data indicate a subsurface transport of contaminated water to surface waters. The high prevalence of enteroviruses throughout the study area suggests a chronic pollution problem and potential risk to recreational swimmers in and around Sarasota Bay.     

长江三峡工程库区宝塔坪滑坡前缘塌岸预测及防护

以长江三峡工程库区奉节宝塔坪滑坡为例，介绍滑坡前缘塌岩预测及防护工程设计方法，重点是石笼垫护坡设计。宝塔坪库岸段潜在的塌岸部位是滑坡前缘地带，该处阶地发育，仅第四系松散堆积物厚度即达50m以上。水库塌岸预测首先在滑坡前缘工程地质分带的基础上进行，对不同的分带用卡丘金法分别预测塌岸宽度，并对预测要点给予详细的说明。其次，分析了塌岩对滑坡稳定性的影响。这些工作揭示了滑坡体前缘防护的必要性。最后针对三峡水库运行特点及宝塔坪滑坡工程地质条件，确定滑坡前缘护坡工程方案，即自145－177m高程范围采用石笼垫和石笼挡土墙2类结构型式，并给出具体的设计方法。     

滑坡发生时间预报分析

系统论述了滑坡监测资料的整理方法：滤波和等时化。讨论了滑坡运动响应的主要组成成分。重点阐述了滑坡发生时间预报的理论基础，此基础不同于一般物理方程建立的思路，而是直接来源于观察和经验总结，并抽象为一定的数学模型。单次滑坡发生的整个过程包括孕育、如速、减速、停止等4个阶段，滑坡发生时间则指加速向减速转换的特征时间点，此点是滑坡爆发的峰值点，也是需要预报的特征时间。能够反映滑坡如此运动过程的典型数学函数是Pearl曲线，本质上此S型曲线与系统有阻尼的自由振动微分方程是一致的，也与生物群体演化的虫口方程一致，它们都共同反映了物质运动的一般规律，因此可以用来预测滑坡运动过程。直接运用一般力学报分方程描述滑坡运动过程的困难在于缺乏对滑体系统力学参数的精确把握，直接运用Logistic虫口微分方程则存在模型参数识别的困难，作者还发现某些误用灰色系统理论对Verbulst非线性方程，参数进行辩识。文末，为展示方法而不强调结果，以拥有10a监测资料的某滑坡为例，分析预报了滑坡活动过程，并进行了预测结果的数学检验。     

易滑动微型构造的工程地质及岩土工程意义

在易滑动理论提出的早期阶段，本文提出了具有岩土工程层次的微型易滑动构造概念。由于易滑动理论研究对象“易滑动环境系统”具有层次性，因而还存在超大型，大型，区域易滑动构造。其中微型易滑构造是基础，包含于更高层次的易滑动构造之中，微型易滑构造直接与场地工程建设发生联系，因而其研究对工程地质对岩土工程学进展有重要的意义。文中论述微型构造在边坡工程，隧道工程，地基工程中的作用，并强调这是岩石力学模型建立的