共查询到20条相似文献，搜索用时 15 毫秒
1.
湖南省隆回县金山矿区地层板理发育,造斜强度大,钻孔偏斜一直是制约该矿区钻探施工的瓶颈问题。通过采用钻孔初级定向与使用LZ型连续造斜器实施受控定向相结合的施工工艺,钻孔轨迹得到有效控制,成功解决了金山矿区钻孔偏斜问题,达到了地质预期目的。 相似文献
2.
基于微结构张量理论的柱状节理岩体各向异性强度分析 总被引：2，自引：0，他引：2
复杂的结构面是控制岩体力学性质的主要因素,由结构面引起的岩体各向异性一直是岩体力学研究的热点问题。柱状节理是一类特殊的岩体地质结构面,具有强烈的各向异性特性,微结构张量理论是目前国际岩石力学领域一种较有效地探讨结构面各向异性问题的新方法。材料的微结构张量和加载向量是微结构张量法描述的两个重要参量。采用多组节理面局部坐标系与整体坐标系的投影关系,定义了材料的微结构张量计算方法,引入各向异性参数ψ表述微结构张量在加载方向的投影,将其引入Jaeger针对岩体沿节理面滑动破裂提出的基于Mohr-Coulomb强度准则,得到了多组节理岩体的各向异性强度准则。同时,结合白鹤滩坝址区的柱状节理特性,分析柱状节理引起的各向异性对坝址区稳定性的影响 相似文献
3.
采用法向矢量单位圆描述结构面剖面线粗糙度,从各微分段的角度关系阐述粗糙度,进而将二维问题转化为一维问题处理并提出"角度粗糙度"的概念.考虑到各微分段的实际长度对粗糙度的贡献,采用加权均值与加权方差定量描述角度粗糙度;角度粗糙度越大表明该剖面越粗糙.对规则剖面线与不规则剖面线采用"角度粗糙度"进行描述,所得结果跟已有的剖... 相似文献
4.
节理岩体几何结构非常复杂,研究其渗流特性对于指导含水岩层稳定性分析具有重要价值。应用离散裂隙网络模型DFN方法,基于VC++6.0软件平台,建立了平面渗流分析方法,分析了节理岩体不同几何分布情况下的渗透率张量特征,通过定义渗流定向性系数对岩体渗流的定向性特征进行了定量分析。结果表明：单组节理岩体渗流具有明显的各向异性特征,渗流定向性随着节理角度变化显著;节理随着节理贯通性增加,节理渗透率呈现对数增加趋势;两组节理情况下,各向异性特征随着节理组间夹角变化;两组节理岩体渗流特征研究中,正交分布下,岩体仍存在各向异性,但渗流定向性系数较低;当节理倾角服从正态分布时,随着节理倾角标准差增大,渗透率增加;两组节理夹角不同时,节理渗透主方向倾角随着夹角增大而相应增大,基本沿两组节理夹角方向的角平分线方向。 相似文献
5.
A numerical procedure to determine the equivalent permeability tensor of a fractured rock is presented, using a stochastic REV (Representative Elementary Volume) concept that uses multiple realizations of stochastic DFN (Discrete Fracture Network) models. Ten square DFN models are generated using the Monte Carlo simulations of the fracture system based on the data obtained from a site characterization program at Sellafield, Cumbria, UK. Smaller models with varying sizes of from 0.25 m×0.25 m to 10 m×10 m are extracted from the generated DFN models and are used as two-dimensional geometrical models for calculation of equivalent permeability tensor. The DFN models are also rotated in 30º intervals to evaluate the tensor characteristics of calculated directional permeability. Results show that the variance of the calculated permeability values decreases significantly as the side lengths of the DFN models increase, which justifies the existence of a REV. The REV side length found in this analysis is about 5 m and 8 m with 20% and 10% acceptable variations, respectively. The calculated directional permeability values at the REV size have tensor characteristic that is confirmed by a close approximation of an ellipse in a polar plot of the reciprocal of square roots of the directional permeability.
相似文献
| Ki-Bok MinEmail: Phone: +46-8-7907919Fax: +46-8-7906810 |
6.
岩土材料的强度往往表现出很强的各向异性,而已有的各向同性强度准则不能够描述这一特性。提出一个岩土材料的各向异性强度准则。为了描述材料的各向异性,引入了一个由应力张量和组构张量的联合不变量表达的各向异性参数。该参数可以描述加载方向和材料组构方向的夹角。强度准则是基于材料在子午面和偏平面上的破坏特性而建立的,这为描述广义的材料强度各向异性提供了方便。与原各向同性强度准则相比,各向异性强度准则只引入了两个新的模型参数,而且所有的模型参数都可以通过常规的室内试验结果确定。该准则的预测结果与砂土、黏土、天然黏土和岩石的试验结果比较表明,它能够很好地描述岩土材料强度的各向异性 相似文献
7.
Kingshuk Roy Choudhury 《Mathematical Geosciences》2009,41(5):535-553
Finite strain estimation is a widely used technique for the study of rock deformation in structural geology. One particular
algorithm proposed by Shimamoto and Ikeda uses the ‘average shape matrix’ of deformed markers. This paper provides a detailed
error analysis for resulting strain estimates in two dimensions. When the number of markers exceeds 100, estimators of components
of the strain tensor are shown to have an approximately Gaussian distribution with variances that increase with their mean.
Equal variance estimators are obtained by applying a log transform for the elongation and an arcsin transformation for the
orientation estimates. Confidence interval formulae for strain tensor components are proposed. Lithology specific constants
arising in these formulae are estimated from undeformed samples. The results are validated by application to simulated data
as well as observational data from thin sections of sandstone sampled from SE Ireland. 相似文献
8.
The spatial distribution of joint orientations features self-similarity. Based on the fractal theory, a new method for meshing of Schmidt pole diagram has been established to study the fractal dimension of the orientation pole distribution of joint. Meshing of Schmidt pole diagram by equal area is performed in both circumferential and radial directions. When the cycle number n is set, the circle is evenly divided with n diameter lines to obtain 2n sectors of equal area; meanwhile the radius R is divided n times to obtain n rings, and specific ring radii are set to perform meshing of Schmidt pole diagram by equal area, thus obtaining different side lengths of cells and corresponding number of cells occupied by poles; on this basis the fractal dimension of joints was calculated. This method is applied to the research on the fractal dimension of joints in rock mass of mine. The results of the research showed that the method with fewer parameters made the process in which the fractal dimension of the orientation pole distribution of joint was solved simply and easy to operate, and calculating the fractal dimension of the orientation pole distribution for joint by this method could better describe the dispersity and complexity of the orientation distribution of joint. 相似文献
9.
G. S. Srivastava 《Mathematical Geology》1977,9(1):3-38
Optical processing is a fast, easy, economical, and reliable method of quantifying map patterns. A reduced transparency of a zebra-like pattern, obtained by blackening in alternate contour bands of a map, is used as input to an optical system of a laser source and objective lens to produce Fourier transforms. By sampling the intensity distribution across the transform, information about the spatial frequency (periodicity) and orientation in the original map can be inferred. Parameters used for comparing the map images are the values of intensity distribution in the transform. These intensities are normalized and subjected to comparison using various similarity methods. Cross-multiplication of the intensities is suggested as a measure of vectorial comparison of the orientations. By plotting the directional intensities into a polar coordinate system, rose diagrams are prepared for visual comparison. Optically derived parameters are independent of scale and other restrictive and limiting requirements as demanded in techniques of map analyses based on numerically derived parameters. The technique can be used in analyzing other pictorial data including aerial photographs, rock-fabric diagrams, and thin sections. 相似文献
10.
11.
The mechanical behaviour of a rock mass is strongly affected by discontinuities such as faults and joints. In this paper, a damage mechanics theory is proposed which deals with some sets of discontinuities distributed in a rock mass, for example, joint systems. In this theory, the distributed discontinuities are characterized by a second-order symmetric tensor, called the damage tensor. By introducing the damage concept, the deformation and fracturing behaviour of the rock mass can be reated in a framework of continuum mechanics. A numerical procedure is developed in order to implement the damage mechanics model by using the finite element method. The theory and numerical analysis are applied to several laboratory tests and a practical underground opening problem. Numerical results are compared with measured data. 相似文献
12.
Richard J Lisle 《Journal of Structural Geology》1985,7(1):115-117
A measure of the degree of preferred orientation of directional data defined by Woodcock as the ratio of the maximum and minimum eigenvalues of the orientation tensor (S1/S3) has a disadvantage when used as the statistic for a test of uniformity. This drawback arises because the distribution of S1/S3 under random sampling is not independent of the shape or K value of the sample. An alternative strength parameter also based on the eigenvalues, is proposed. 相似文献
13.
Katsushi Sato 《Mathematical Geosciences》2012,44(5):635-644
Recent stress tensor inversion methods for fault-slip analysis are used to distinguish between multiple stress states to elucidate spatiotemporal change of the earth’s crustal tectonics. An estimator named the stress difference has been a practicable tool to measure the difference between stress solutions of inversion analysis. This measure corresponds to the expected difference in shear stress direction on a randomly oriented fault plane, which is, however, an approximation including several degrees of deviation. This study investigated the formula of stress difference and found the exact physical meaning, specifically the expected difference in shear stress vector which carries information on magnitude as well as direction. The present discovery is based on the analytical proportionality between the second invariant of stress tensor and the root mean square magnitude of shear stress for all orientation of fault planes. The meaningless difference in non-dimensional shear stress magnitude was found to be incorporated into the value of stress difference. This fact is not convenient for fault-slip analysis dealing only with orientations. 相似文献
14.
15.
16.
Palaeocurrent and palaeohydrologic analysis of some vertical profiles through a Cretaceous braided stream deposit, Banks Island, Arctic Canada 总被引：1，自引：0，他引：1
ANDREW D. MIALL 《Sedimentology》1976,23(4):459-483
A study of directional variability has been carried out on five vertical profiles containing a total of approximately 195 superimposed planar crossbed sets. The latter are interpreted as the deposits of braid bars. Detailed measurements on one set revealed within-set variance of 93. Within river tract, between-bar variance was obtained by calculating a ten-point moving average for each profile, and subtracting the actual azimuth at each point from the moving average value. Variance at this level is 980, which compares closely with data obtained from modern braided streams. Variability in the moving average azimuth is interpreted as the result of meander migration in the entire channel system. Sinuosity can be estimated from this variability, using a geometrical approximation. It ranges from 1.03 to 1.13. Changes in stream competency with time are indicated by vertical changes in directional variance and set thickness. When accompanied by changes in mean azimuth, as in one of the present five profiles, the data suggest successive deposition by two distinct stream systems. A Markov chain analysis of the data sequence indicates a weak memory effect. Short sequences of bar deposits were formed by streams which varied little in orientation, and these are separated from one another by sequences showing random directional fluctuation. The hydrology of the Isachsen rivers was investigated using Schumm's (1968a, b, 1969, 1972) empirical relationships for modern rivers. Owing to inherent uncertainties in these relationships and a wide margin of error in the input data (principally associated with estimates of depth and width of the Isachsen streams), the results have a validity only at the order-of-magnitude level. Individual Isachsen rivers are estimated to have had drainage areas of between 5000 and 30,000 km2; this information is of use in reconstructions of palaeogeography and tectonic history. 相似文献
17.
Du Shigui 《中国地质大学学报(英文版)》1998,9(1):5-2
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍｅｃｈａｎｉｃａｌｂｅｈａｖｉｏｒｏｆｒｏｃｋｊｏｉｎｔｓｉｓａｃｏｍｐｌｅｘｓｙｓ－ｔｅｍｗｈｉｃｈｉｓｃｏｎｔｒｏｌｅｄｂｙａｌｏｔｏｆｆａｃｔｏｒｓ．ＦｒｏｍｔｈｅＪＲＣ－ＪＣＳｍｏｄｅｌ（ＢａｒｔｏｎａｎｄＣｈ... 相似文献
18.
裂隙岩体内的节理往往是变化的,有时甚至变化很大。测得大量节理产状以后,对其分组是一项基础性的工作,但是如何分组目前还没有很好的理论和方法。采用快速聚类分析的方法,将节理产状的样本数据划分为不同的簇,利用极大似然估计的原理,通过数值方法求解费歇尔概率分布模型的参数,并用皮尔逊检验说明了费歇尔逊概率模型的有效性。通过不同簇的概率模型计算及其簇心的分布特性比较说明了簇数分类的适度性。利用所提出的快速聚类分析方法及其推导的计算公式,可以方便地求解费歇尔分布的参数。结合皮尔逊检验,形成了解决这类问题的系统实用的方法。 相似文献
19.
侵入岩油气藏广泛分布于世界各盆地中,具有良好的油气勘探潜力.但对原生孔隙发育的岩脉储层模式的研究尚未引起足够的关注.本文以新西兰基督城Lyttelton火山西北部的中新世浅成岩脉为研究对象,根据野外露头调查、孔渗测试、图像分析和经验公式的渗透率计算,对其孔隙构成、储层分布模式和储层控制因素进行分析.结果 表明:该区浅成侵入岩为孔隙-裂缝型储层,储集空间以气孔为主,冷凝收缩缝次之;气孔可见定向拉长的大直径椭圆形和离散的小直径圆形两类,对孔隙度的贡献以前者为主;柱状节理可见规则和不规则两类,后者的裂缝面密度较高;具有中孔-中渗的特征,局部高孔-高渗;柱体横截面形态和规则性是影响地层渗透性的关键因素.整体上,浅成岩脉从下到上孔隙度由小变大,柱状节理由规则变为不规则;气孔可由柱状节理沟通,其连通性受柱状节理缝间距、缝宽,以及定向拉长气孔与柱状节理之间的夹角控制;Lyttelton火山的浅成岩脉显示,冷凝固结阶段气孔的初始连通率可高达35％.综上,浅成岩脉可具有良好的储集性能,气孔初始连通性较高,可作为有利的勘探目标. 相似文献
