Effect of rod friction on vane shear tests in very soft organic harbour mud     

Benjamin F. Schlue  Tobias Mörz  Stefan Kreiter 《Acta Geotechnica》2007,2(4):281-289

Very soft organic harbour mud is increasingly used as a filling and construction material in harbour construction and reorganization. The undrained shear strength of such soft sediments is the critical geotechnical soil parameter with regard to any specific construction design. Field and laboratory vane shear testing is a standard method to quickly determine this important parameter. So far, the effect of rod friction on vane shear tests in very soft organic soils is unclear. In this study we present results from laboratory experiments on harbour mud from a construction site in northern Germany. Relations among vane and rod geometry, penetration depth, water content, rod friction and undrained shear strength are derived. Based on these relations the influence of rod friction on vane shear test results is investigated. The results indicate that field and laboratory vane shear test measurements may be significantly influenced by rod friction. Methods are proposed to correct for the rod influence, which is shown to increase with rising water contents.  相似文献   

Performance of surface footing on geocell-reinforced soft clay beds   总被引：2，自引：0，他引：2  

Sitharam G. Thallak  Sireesh Saride  Sujit Kumar Dash 《Geotechnical and Geological Engineering》2007,25(5):509-524

This paper presents the results of laboratory model tests carried out to develop an understanding of the behaviour of geocell-reinforced soft clay foundations under circular loading. Natural silty clay was used in this study. The geocells were prepared using biaxial polymer grid. The performance of the reinforced bed is quantified using non-dimensional factors i.e., Bearing capacity improvement factor (I_f) and Percentage reduction in footing settlement (PRS). The test results demonstrate that the geocell mattress redistributes the footing load over a wider area thereby improving the performance of the footing. The load carrying capacity of the clay bed is increased by a factor of up to about 4.5 times that of unreinforced bed. From the pressure-settlement responses, it is observed that the geocell-reinforced foundation bed behaves as a much stiffer system compared to the unreinforced case indicating that a substantial reduction in footing settlement can be achieved by providing geocell reinforcement in the soft clay bed. The maximum reduction in footing settlement obtained with the provision of geocell mattress of optimum size placed close to the footing is around 90%. Further improvement in performance is obtained with provision of an additional planar geogrid layer at the base of the geocell mattress.  相似文献   

滇中红层工程地质特性研究     

刘成 《云南地质》2007,26(4):428-438

介绍滇中红层形成的地质历史背景,红层分布范围,主要地层岩性及区内地质构造。重点讨论滇中红层特别是红层软岩的岩体原生结构,及后期受构造改造的岩体结构特性,岩体风化特性,岩体水理作用特性,岩体物理力学性质等四方面的工程地质特性。  相似文献   

Dynamic of the freshwater–saltwater interface in a karstic aquifer under extraordinary recharge action: the Merida Yucatan case study     

Oscar Escolero  Luis E. Marin  Eloisa Domínguez-Mariani  Sandra Torres-Onofre 《Environmental Geology》2007,51(5):719-723

A hydraulic analysis of the interface between freshwater–saltwater behavior was done in the Merida Yucatan zone, two machines that constantly register the groundwater levels were installed, and three electric conductivity logs were taken from wells. When comparing the measured results with the ones obtained using theoretical equations developed to calculate the freshwater–saltwater interface position, it was proved that in some cases these equations can be applied, and in others not. Two effects that rule the behavior of karst aquifers in extraordinary conditions were found.  相似文献   

土性指标和地层性质对水泥搅拌桩成桩质量的影响     

符学兵 《江苏地质》2007,31(4):370-372

从水泥土的固化机理出发,结合水泥搅拌桩桩身标准贯入试验和水泥土配合比试验,分析讨论了土性指标、土质条件和地层性质对水泥搅拌桩成桩质量的影响。  相似文献   

Bayesian data fusion in a spatial prediction context: a general formulation   总被引：1，自引：1，他引：1  

P. Bogaert  D. Fasbender 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):695-709

In spite of the exponential growth in the amount of data that one may expect to provide greater modeling and predictions opportunities, the number and diversity of sources over which this information is fragmented is growing at an even faster rate. As a consequence, there is real need for methods that aim at reconciling them inside an epistemically sound theoretical framework. In a statistical spatial prediction framework, classical methods are based on a multivariate approach of the problem, at the price of strong modeling hypotheses. Though new avenues have been recently opened by focusing on the integration of uncertain data sources, to the best of our knowledges there have been no systematic attemps to explicitly account for information redundancy through a data fusion procedure. Starting from the simple concept of measurement errors, this paper proposes an approach for integrating multiple information processing as a part of the prediction process itself through a Bayesian approach. A general formulation is first proposed for deriving the prediction distribution of a continuous variable of interest at unsampled locations using on more or less uncertain (soft) information at neighboring locations. The case of multiple information is then considered, with a Bayesian solution to the problem of fusing multiple information that are provided as separate conditional probability distributions. Well-known methods and results are derived as limit cases. The convenient hypothesis of conditional independence is discussed by the light of information theory and maximum entropy principle, and a methodology is suggested for the optimal selection of the most informative subset of information, if needed. Based on a synthetic case study, an application of the methodology is presented and discussed.  相似文献   

开放式地理信息系统(OpenGIS)与互操作技术分析   总被引：8，自引：0，他引：8  

冯琰  施一民 《测绘工程》2002,11(4):22-24

地理信息系统技术在取得巨大发展的同时，其孤立性、封闭性的缺陷越来越不适合现代信息社会的要求，开放式地理信息系统（OpenGIS）规范和互操作技术的提出，不仅为数据共享提供了崭新的思路，而且将GIS带入了开放的时代，从而使得各个系统间实现不同类型地理数据和地理处理方法的透明访问成为可能。本文主要就OpenGIS规范和互操作技术作了一些探讨，最后结合我国的实际情况，分析了OpenGIS在我国的应用现状与未来展望。  相似文献   

三级层序界面野外露头的识别判断标志——以南盘江坳陷晚古生界地层为例   总被引：1，自引：0，他引：1  

张国常 《贵州地质》2002,19(2):93-98

在岩性及岩相观察基础上以不同类型的米级旋回层序作为分层和描述地层的基本工作单元，把米级旋回层及其有序叠加形式作为识别三级层序的基础，通过野外露头的详细观察、描述认为：在南盘江坳陷晚古生界地层中SB1型层序界面是以区域平行不整合面、古风化壳、古土壤层、下伏地层的强烈白云石化以及沉积物转化面为识别标志；SB2型序界面是以沉积物转化面、地层结构转化面及古土壤层为识别标志：SB3型层序界面是以凝缩段直接覆盖在下伏地层之上为识别标志；SB型层序界面是以上下地层的岩性组合、地层结构转化面及年代地层为识别标志。  相似文献   

(斜长石 + 黑云母 + 石英 ) NaCl(NaHCO3) H2O 矿物蚀变与金矿化反应研究 : 450～ 250 ℃和 50 MPa   总被引：1，自引：0，他引：1  

王玉荣  王志祥  张生  胡受奚 《地球化学》2001,30(5):498-503

采用（斜长石＋黑云母＋石英）这三种单矿物组合与1mol/L NaCl或0．5mol/L NaCl 0.5mol/L NaHCO3溶液在450－250℃和50MPa条件下反应7d。实验表明，反应后流体pH值发生了变化，NaCl介质向酸性变化，N aCl NaHCO3介质向中性转化。溶液中K,Ca,Mg,Fe和Au量也随之发生变化。矿物表面发生溶解和离子置换等反应。斜长石表面形成钠长石反应边，黑云母变色，石英重结晶，反应器皿金管中的金被溶解后在金管壁和黑云母表面重结晶，黑云母周边出现红色Fe2O3，在450℃的NaCl介质中，金含量可达1070μg/g，但随温度下降迅速减低，在NaCl NaHCO3介质中，金含量较低，显著，金的活化迁移和富集与Cl,pH,Fe^3 /Fe^2 密切相关，这中金起到示踪作用，显示出金在水／岩反应中的原电池效应。  相似文献   

硫化物固—液界面电化学效应实验探讨          下载免费PDF全文

贾建业  兰斌明等 《地质论评》2001,47(3):250-254

硫化物作为一类重要的常见矿物，目前国内外对其表面矿物学特征研究有限。具体到硫化物固－液界面处的行为机理，前人的研究程度就更低了。笔者自行设计了一个Fe1-xS-Cr^6 原电池，通过实测电动势（E），t-E关系曲线，溶液可见光吸收谱及其λ－A关系曲线，阐明硫化物与Cr^6＋溶液间的界面行为机理。认为其界面行为过程为；硫化物溶解→离子反应（氧化还原）→吸附Cr^3 。该原电池与一般原电池结构不同，其主要差别在于将反应电极和测量电极分开，从而解决电极反应过程中的浓度极化问题，提高了电化学实验的精度。该研究成果有助于揭示矿物－液体相互作用机理，完善和丰富表面矿物学研究内容，深化化界面成矿理论，并对环境治理，矿物材料应用等开发领域具有重要的参考价值。  相似文献