小秦岭金矿含金石英脉中黄铁矿晶体的表面微形貌研究   总被引：1，自引：0，他引：1  

张良钜 《岩石矿物学杂志》2004,23(2):167-172

利用微分干涉显微镜、扫描电镜、透射电镜等对小秦岭金矿含金石英脉中黄铁矿晶体的表面微形貌进行了研究。黄铁矿晶体的{210}面上发育自由生长层，表明{210}面是F面，其生长机理受二维成核层生长所制约。除简单的五角十二面体外，其他形态黄铁矿晶体的{210}面上也发育有自由生长层。{210}面上的正条纹有些是由{100}面上生长层的边缘台阶在{210}面上叠堆形成，另一些正条纹则是{210}面上生长层边缘台阶堆叠的产物。透射电镜和电子衍射花样研究表明，负条纹黄铁矿晶体是由30～50nm大小的核团经自动定向附生作用形成，每个核团不是单晶体，而是由许多早先在溶液中形成的小微晶聚合而成。这些特征表明负条纹黄铁矿晶体是在溶液过饱和度极高和温度梯度小的理想环境中形成，它的形成与杂质无关。PBC理论和唐纳-哈克定律能较好地解释自然界中黄铁矿晶体{100}面上普遍发育自由生长层、而{210}面上自由生长层极为罕见的原因。除日本释迦内矿区黑矿之上的浮岩凝灰岩中产生出负条纹黄铁矿晶体外，在石英脉型金矿床中也有负条纹黄铁矿晶体产出。  相似文献   

A Physical and Numerical Investigation on the Stability of Shallow Tunnels in Strain Softening Media   总被引：11，自引：0，他引：11  

D. Sterpi  A. Cividini 《Rock Mechanics and Rock Engineering》2004,37(4):277-298

Summary The behaviour up to failure of shallow underground openings is discussed on the basis of some laboratory, small-scale model tests and of finite element simulation. The experimental results are first illustrated. They were obtained from two-dimensional (plane strain) and three-dimensional tunnel models tested under standard gravity conditions. Then, the phenomenon of strain localisation that characterizes the medium surrounding the model tunnels is discussed, recalling two alternative approaches for its numerical interpretation. On this basis, a finite element procedure for strain softening analyses is outlined and applied to the simulation of the tests in both two- and three-dimensional conditions. The comparison between experimental and numerical results leads to some conclusions on the influence of strain localisation on the overall behaviour of shallow tunnels and on the stability of their headings.  相似文献   

合理设计岩屑规程保证正常钻进条件——金刚石钻进技术专题之一          下载免费PDF全文

汤凤林  段隆臣  В.Ф.Чихоткин  刘晓阳 《探矿工程》2004,31(6):45-48

论述了正常钻进的条件，提出了合理岩屑规程是保证正常钻进的关键和设计钻头的主要依据之一，讨论了岩屑规程与金刚石钻头唇面工作状态、孔底表面粗糙度和岩屑粒度的关系，提出了相应的建议。  相似文献   

Analysis of shaft resistance of jacked piles in sands     

Rodrigo Salgado 《国际地质力学数值与分析法杂志》2011,35(15):1605-1635

In recent years, pile jacking has become a viable alternative installation method for displacement piles. Pile jacking produces minimal noise, vibration and air pollution during installation. In addition, it is possible, at the end of jacking, to have a good estimate of the ultimate static capacity of the pile. In this paper, the shaft resistance of piles jacked into sand is studied using one‐dimensional finite element analysis. The finite element simulations, using a two‐surface plasticity model, demonstrate the effects of relative density and confinement on the unit shaft resistance of piles jacked in sand. The impact of the number of jacking strokes on the unit shaft capacity is also assessed. Based on the numerical results, we developed equations for shaft resistance quantifying the effects of relative density, initial confinement and number of jacking strokes. Predictions using these equations are compared with data obtained from centrifuge tests and field tests. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Halin图的色数问题     

朱建  陈丽娟 《南京气象学院学报》2016,8(3):286-288

Halin图G=T∪C,其中T为每一非悬挂点(内点)度数至少为3的平面树,C为连接T的所有悬挂点的圈.文章分别讨论了Halin图的星色数、面色数及分数色数.  相似文献   

辐射井技术在尾矿库降排水工程中的应用          下载免费PDF全文

阮茂盛  奚兴富  周晨晨 《探矿工程》2016,43(4):72-75

尾矿库是我国重大危险源之一,而尾矿库内的浸润线又是坝体安全的重要指标之一,为有效排出尾矿中的水,降低尾矿库内浸润线,本文通过辐射井技术在尾矿库降排水工程中应用的多个成功工程实例,归纳、总结并提出该技术在尾矿库应用过程中的设计思路、施工要点及工艺方法等。  相似文献   

国际油气井钻头进展概述 (四)——PDC钻头发展进程及当今态势（下）          下载免费PDF全文

左汝强 《探矿工程》2016,43(4):40-48

近年来,非平面PDC切削齿,如浅凹面PDC齿、Stinger毒牙中心锥形齿、Stinger毒牙刀翼锥形齿、AxeBlade斧式脊形PDC齿和StayCool保持冷却PDC齿等制造的钻头,逐步在油气钻井中得到有效的应用。这些钻头能够以较高的钻进效率和工作寿命钻进某些硬岩和研磨性地层。为了满足水平钻井,特别在页岩气水平井中能够强力排除岩屑,并具有优良的钻井导向性能,国际著名公司推出了许多新型钻头,如ONXY Ⅱ矛式PDC钻头、Seeker导向PDC钻头、CounterForce反力PDC钻头、Speed快速PDC钻头等用于当代油气钻井,取得了良好的效果。文章还介绍了Defyer DPA套管钻头与CuttPro PDC防剪切保护帽。提出了以下建议：继续深入研究PDC钻头,以提高其性能,更好地满足油气钻井的要求;组合化钻头是油气钻头发展的重要趋势;比金刚石性能更好的钻头切削材料有可能今后发现或合成,可用于制作更佳钻井钻头;我国钻头企业需重组和发展状大;各种钻头技术创新应该加强。  相似文献   

基于镜像图的LRC和CRC偏差结合的人脸识别     

陈铭  周先春  周杰 《南京气象学院学报》2019,11(3):340-345

为了提高人脸识别率及更好地显示人脸特征,本文提出了一种基于镜像图的LRC和CRC偏差结合的人脸识别方法.该方法首先生成一种镜像人脸,再通过融合原始人脸和镜像人脸形成新的混合训练样本,最后利用LRC和CRC偏差结合进行人脸识别.新方法增加了训练样本的数目,克服了由于光照和姿态等外部因素带来的影响.实验结果表明,镜像图与LRC和CRC偏差结合的人脸识别方法提高了人脸识别的准确性.  相似文献   

The effect of pore water pressure on tunnel face stability          下载免费PDF全文

Qiujing Pan  Daniel Dias 《国际地质力学数值与分析法杂志》2016,40(15):2123-2136

The kinematic approach in combination with numerical simulation is used to examine the effect of pore water pressure on tunnel face stability. Pore water pressure distribution obtained by numerical calculations using FLAC^3D is used to interpolate the pore water pressure on a 3D rotational collapse mechanism. Comparisons are made to check the present approach against other solutions, showing that the present approach improves the existing upper bound solutions. Results obtained indicate that critical effective face pressure increases with water table elevation. Several normalized charts are also presented for quick evaluation of tunnel face stability. At the end of the paper, the influence of anisotropic permeability on tunnel face stability is also discussed, showing that the isotropic model leads to an overestimation of the necessary tunnel face pressure for anisotropic soils. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Support and strata interaction at coal faces     

Ke-Bin Zhang 《Geotechnical and Geological Engineering》1988,6(1):85-88

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