小浪底工程岩体力学参数研究

本文系统研究了小浪底工程的岩体的强度特征,采用了室内试验,野外结构面统计,工程地质类比法、模型试验法和Hoek Brown的经验法,估算了工程岩体的力学指标,指出了上述各种方法中所存在的不足,认为在工程实践中,应尽可能使用多种估计方法,交叉校核所得参数,以提高参数的可靠性,保证工程的安全,节约投资。     

The use of inclined hemisphere projections for analyzing failure mechanisms in discontinuous rocks

This paper demonstrates the advantages of using inclined stereographic projections in kinematic analysis of rock blocks in discontinuous rock masses. Some examples of limiting cases are presented. The application of inclined projections is illustrated by its use in a mine slope in Brazil. It is clear from the discussion of these examples that inclined hemisphere projections provide better results than horizontal projections. It is also demonstrated that horizontal projections can lead to incorrect results in limiting cases.     

Geotechnical and geoenvironmental characteristics of man-made underground structures in Cappadocia, Turkey

Underground cities and semi-underground settlements, most of which are 1500 years at least, exist in the Cappadocia Region of Turkey. These man-made rock structures are carved in soft tuffs and the best examples of long-term performance of man-made structures in the field of rock engineering. The tuffs also have good thermal isolation properties to be used as housing and storage of foods. In this article, the authors are only concerned with physical and short-term mechanical characteristics due to the wide-spectrum of the theme and the in situ characterization of the Cappadocia tuffs, and the results of investigations are presented. In addition, a critical overview on possible engineering geological problems at Cappadocia with mechanical aspects of historical and modern rock structures and their implications in rock engineering is made. From the experimental results in the field, it is evident that the engineering characteristics of these rocks do not show significant changes in vertical and horizontal directions. However, they are prone to atmospheric conditions. In addition, temperature and humidity measurements at different floors of the underground cities and various parts of semi-underground settlements indicated that variations in climatic conditions of the openings are very small when compared to those outside the ground surface.     

Laser microprobe for the study of noble gases and nitrogen in single grains: A case study of individual chondrules from the Dhajala meteorite

A laser microprobe capable of analysing nitrogen and noble gases in individual grains with masses less than a milligram is described. It can be used in both continuous wave (CW) mode, useful for stepwise heating of an individual grain, as well as in pulsed mode, useful for ablating material from a small selected area of a sample, for gas extraction. We could achieve low blanks (in ccSTP units) for 4He(4.8 x 10{-12}),²²Ne(1.0 x 10{-12}),³⁶Ar(1.0 x10 ^-13),⁸⁴Kr(2.9 x 10{-14}),¹³² Xe(2.6 x 10{-14}), and N (87 pg), using this system. Preliminary data for individual chondrules from the Dhajala meteorite show that noble gases and nitrogen from grains as small as 170 microgram can be analysed using the present laser microprobe setup. The amount of trapped neon in Dhajala chondrules is very small, and nitrogen in the chondrules is isotopically heavier as compared to the bulk meteorite.     

Geomechanical Properties of Shear Zones in the Eastern Aar Massif,Switzerland and their Implication on Tunnelling

Summary ¶Rock zones containing a high fracture density and/or soft, low cohesion materials can be highly problematic when encountered during tunnel excavation. For example in the eastern Aar massif of central Switzerland, experiences during the construction of the Gotthard highway tunnel showed that heavily fractured areas within shear zones were responsible for overbreaks in the form of chimneys several metres in height. To understand and estimate the impact of the shear zones on rock mass behaviour, knowledge concerning the rock mass strength and deformation characteristics is fundamental. A series of laboratory triaxial tests, performed on samples from granite- and gneiss-hosted shear zones revealed that with increasing degree of tectonic overprint, sample strength decreases and rock behaviour shows a transition from brittle to ductile deformation. These trends may be explained by increasing fracture densities, increasing foliation intensity, increasing thickness of fine-grained, low cohesion fracture infill, and increasing mica content associated with the increasing degree of tectonic overprint. As fracture density increases and the influence of discrete, persistent discontinuities on rock mass strength decreases, behaviour of the test samples becomes more and more representative of rock mass behaviour, i.e. that of a densely fractured continuum. For the purpose of numerical modeling calculations, the shear zones may be subdivided with respect to an increasing fracture density, foliation intensity and mica content into a strongly foliated zone, a fractured zone and a cohesionless zone, which in turn exhibit brittle, brittle-ductile and ductile rock mass constitutive behaviour, respectively.Received December 17, 2001; accepted January 9, 2003 Published online April 29, 2003     

Compositional Geometry and Mass Conservation

A geometrical structure is imposed on compositional data by physical and chemical laws, principally mass conservation. Therefore, statistical or mathematical investigation of possible relations between data values and such laws must be consistent with this structure. This demands that geometrical concepts, such as points that specify both mass and composition in linear space, and lines in projective space that specify composition only, be clearly defined and consistent with mass conservation. Mass thus becomes the norm in composition space in place of the Euclidean norm of ordinary space. Coordinate transformations inconsistent with this geometry are accordingly unnatural and misleading. They are also unnecessary because correlation arising from the constant mass presents no unusual difficulty in the analysis of the underlying quadratic form.     

宜兴抽水蓄能电站试验洞的反分析研究

结合江苏宜兴抽水蓄能电站地下厂房试验洞量测资料的分析,研究了成层各向异性岩体中洞室工程问题的反分析方法。采用分层均质模型进行反分析计算。计算区域的各层岩层均被分别视为均质各向同性体,初始地应力假设呈线性分布。有限元分析中,对倾斜成层的岩层、软弱夹层及断层节理等分别划分了单元,据以模拟成层岩体的各向异性特征。为使计算过程简化,对离洞室较远的岩层拟按地质资料对材料特性参数赋值,反分析计算的目标未知数为初始地应力和试验洞相邻围岩的弹性模量。结果表明,与工程实践符合较好。     

MTMD对建筑结构多模态控制的减震分析

本文研究了MTMD对建筑结构多模态减震控制。将主结构简化为多自由度模型，MTMD对结构的反力与地震荷载共同作为结构的荷载输入进行分析；基于主结构多模态耦合进行推导分析，阐述了MTMD与结构之间的相互作用关系，提出MTMD的复惯性质量。提出MTMD的控制类型是加速度相关型的无源被动控制。从频域传递函数，白噪声、宽带和窄带地震激励下的结构相对位移和绝对加速度谱密度，以及El-centro地震波作用下结构的地震响应三个方面，分析了MTMD对顶部带有结构附属物的结构的控制效果。并且给出TMD的控制效果加以比较验证。算例说明MTMD多模态控制对结构的相对位移和绝对加速度均有较好的控制效果，并且优于TMD控制效果。     

N同位素质谱分析及其数据处理

本文论述了N同位素质谱分析原理和钢瓶高纯氮标定方法。同时对影响N同位素分析分馏因素作了相应讨论，指出钢瓶子高纯氮同位素标定，要用纯化后的大气氮定值。     

冀北张麻井铀钼矿床黄铁矿化蚀变岩地球化学迁移特征及与成矿关系亲缘性的讨论

张麻井铀钼矿床是中国北方最大的与火山岩有关的热液铀矿床，围岩蚀变广泛发育，其中黄铁矿化在该矿床分布虽 较为局限，但是与铀钼成矿关系密切。为了研究黄铁矿化蚀变与铀、钼成矿的亲缘关系，文章对张麻井的黄铁矿化蚀变岩 进行主、微量元素分析，并选择Yb作为不活动组分，使用质量平衡迁移计算方法， 利用Grant公式对其组分迁移进行定量 计算。岩石地球化学特征显示，黄铁矿化蚀变岩的TFeO含量极高，介于11.24%~24.57%之间(平均18.45%)，其中Fe2O3含量 10.78%~25.25% （平均18.64%）、FeO含量1.43%~1.90% （平均1.69%），Fe2O3/FeO比值平均为10.99，有可能受到后期氧 化。黄铁矿化蚀变岩在Isocon图解上等浓度线斜率小于1，表明整体发生了组分的带入，带入的主要组分为大量的TFeO （131倍），成矿元素Mo（884倍）、Pb（11倍）、U（4.9倍）、V（2.8倍）、Ta（0.44倍）、Cu（0.64倍），碱金属Na2O（0.45 倍），以及Cd（424倍）、Bi（13倍） 等；带出的主要组分有碱金属Li（-0.73）、K2O（-0.17），成矿元素Zn（-0.38）、Cr （-0.37），以及Eu（-0.58）、Sc（-0.25） 等。其中SiO2略微减少（-0.03），带入的Mo含量远大于U的含量，据此认为黄铁 矿化与钼成矿关系更为密切。