共查询到18条相似文献，搜索用时 192 毫秒
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水系结构的分形和分维——Horton水系定律的模型重建及其参数分析 总被引：26，自引：3，他引：26
基于标准分形水系等级序列的镜象对称性，重建水系构成定律：从Horton第一，第二定律出发，导出关于河流长度与位序关系的三参数Zipf模型，从Horton第二，第三定律出发，导出广义的Hack定律；从Horton第一，第三定律出发，导出关于河流长度一流域面积关系的异速生长方程，根据上述数学变换结果建立了水系分维方程式，澄清了不同空间，不同类型的各种维数之间的数理关系。 相似文献
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中国旱涝灾害的分形结构 总被引：15，自引：1，他引：15
基于分形理论在中国旱涝灾害研究方面所存在的问题,首先系统地分析了中国华北区、西北区等不同区域和松花江、长江等不同流域旱涝灾害的分形结构,其次以唐山市为例系统分析了同一地点不同等级旱涝灾害分维的时序变化及其关系,进而探讨了以分维为中介参数在旱涝灾害与其影响因素之间建立定量化经验关系的可能。研究结果表明,中国旱涝灾害具有客观的分形结构,分维是表征中国旱涝灾害发生特征的良好参数;在此基础上,系统地计算出了中国旱涝灾害的分维值、分析了唐山市不同等级旱涝灾害分维的时序变化关系,并建立了辽河、长江等流域水系空间维数与流域洪涝分维之间的定量关系式DF=3．6179DR-4．0242(式中DR为流域水系空间维数,DF为流域洪涝分维)。 相似文献
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对伦坡拉盆地丁青湖组油页岩进行了系统采样和地球化学分析,结果显示该地区油页岩SiO2含量整体较低,K2O/Na2O值较高,Al2O3+Fe2O3为6.43%～10.28%,Al2O3/（Na2O+K2O）为1.7～4.91,含有一定的铁镁质组分和较多的稳定组分;化学蚀变指数CIA为65～85,Th/U值多集中在0.97～3.38,表明油页岩源区经历了相对中等的风化作用,反映温暖、湿润的气候条件;Sr/Ba值为0.45～0.82,V/（V+Ni）值为0.46～0.68,Th/U平均值为0.59,表明丁青湖组油页岩形成于淡水缺氧的湖泊之中。温暖湿润的气候、丰富的生物来源及淡水缺氧的沉积环境是伦坡拉盆地丁青湖组油页岩形成的重要条件。 相似文献
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长江下荆江段分形学特征与河道演化 总被引：1，自引：0，他引：1
采用盒数维法对长江下荆江各不同时期河道岸线的分形学特征进行探讨。研究表明,下荆江河道岸线的盒数维介于1078~123之间,较黄河、海河、滦河等河流的维数要小,相当于黄河下游和长江下游平原区的维数,反映出下荆江河段是高成熟度的河段。这与长江中游地区的其他河段不相称,可能是由江汉-洞庭湖平原长期沉降所造成。河道裁弯之后,河道岸线由复杂变简单,分维数显著减少。裁弯取直事件发生在分维数值为119~123之间,即分维数可作为河道突变事件发生的一个预警参数。 相似文献
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丹江口水库库区及周边地区河网形态、地貌特征及构造活动性意义 总被引：2，自引：2，他引：0
河流作为构造-气候相互作用最为敏感的地貌单元,记录了丰富的水系演化、构造变形以及气候变化等信息。通过研究河流的形成与演化过程来阐述区域地貌和构造活动特征是构造地貌研究的一个突破点,河流形态的空间变化是阐述河流形成与演化特征最为直观有效的方法。丹江口水库库区地貌特征复杂、地质灾害频发、差异性构造活动较为强烈,是开展构造地貌研究的理想场所。通过对丹江口水库库区及周边地区河流形态特征、地貌特征及构造活动特征等进行综合分析发现,河网分维值空间特征与区域内构造活动性较强的断裂的空间分布高度吻合,构造活动性较强的断裂带及周边地区,河网受到构造活动的影响,发育不成熟,河网分维值出现低值,分维值均小于1.115;构造活动性较弱的断裂带及周边地区,河网发育过程中未受到构造活动的影响,发育较成熟,河网分维值高,分维值均大于1.25;而河网分维值空间变化与地形坡度、平均高程等地貌参数相关性不显著。因此,区域构造活动性特征是河网形态空间变化控制的关键因素。利用河网形态的分维特征量化区域构造活动的强弱及各区域构造活动的差异,对于河流的形成与演化、构造活动性及预测地质灾害的发生等方面的研究都有一定的参考价值。 相似文献
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为了探索复杂滑坡轨迹结构演化及其稳定性定量分析计算的新途径, 利用分形分维理论, 分析三峡库首区黄腊石滑坡和黄土坡滑坡边界轨迹的几何分形结构, 并采用盒维数法分别求得黄腊石滑坡西部活动性滑坡群、东部小滑坡群和整个滑坡系统及黄土坡滑坡分形结构的特征性斜率曲线和分维值.计算结果表明: 每个滑坡群的轨迹结构具有其特征性的分维值, 轨迹结构越复杂, 结构层次越清楚, 分维值越高.其中, 黄腊石滑坡西部活动性滑坡群的分维值最高, D =1.483, 黄土坡滑坡的分维值最低, D =1.111.主要结论包括: (1) 滑坡边界轨迹存在统计上的自相似性, 具有分形结构特征; (2) 滑坡轨迹结构的宏观扩展变形过程是一个增维过程, 而不是降维过程; (3) 滑坡轨迹结构越复杂, 有序性越好, 分维值越高, 其稳定性越差; 因此, 分数维可作为衡量滑坡轨迹结构复杂性和稳定性的重要标志. 相似文献
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基于岩体不连续面三维分形维岩体质量评价研究 总被引：1，自引：0，他引：1
岩体内部不连续面分布具有随机性、不规则性,但又具有统计自相似性。基于三维随机不连续面网络模拟技术,对岩体结构统计均质区内的不连续面进行计算机模拟,并应用分形理论计算岩体不连续面分布的分形维数。岩体不连续面分布分维数具有尺寸效应,随着岩体尺寸增大分维数减小,到一定程度趋于稳定。这一稳定的分维值称之为表征分维数,用此值描述不连续面分布特征。将岩体不连续面分布的表征分维数与按传统岩体分类标准所得岩体质量等级进行对比,提出以岩体不连续面分布表征分维数为指标的岩体质量分类方法。在岩体分类基础上,提出基于表征分维数的岩体等效抗剪强度指标的折减计算。 相似文献
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中国干旱内陆流域水体 N、P负荷特征与动态变化——以黑河流域为例 总被引：6，自引：0，他引：6
以黑河流域中游地区为研究区域，通过11年在不同河流断面的长期监测和区域内各类水体如地下水、泉水、水库和河流的空间选点取样分析，研究了干旱内陆流域水体 N、P等植物营养元素的负荷与时空分布及动态变化特征。浅层地下水与河水中NO3-N含量普遍较高，含量超过 1．1 m g／L，大部分平原水库水中NH4-N含量超过 0．3 m g／L；河水与浅层地下水TP、NH4-N与NO3-N含量均呈现沿流域从出山口至下游的显著递增变化，同时还具有明显的随时间递增趋势，其中NH4-N含量在河流出山口及下游断面平均年增加幅度分别为 0．11 m g／L和 0．114 m g／L；流域水体 N、P含量的季节变化明显，黑河流域春季及春夏之交的枯水期大部分河段NH4-N、NO3-N和TP等要素含量为全年最高并出现水质超标污染。控制干旱内陆流域水域尤其是枯水期的 N、P污染，应成为干旱内陆流域水资源保护问题中值得关注的关键内容。 相似文献
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In this study, an assessment of seismicity parameters in the northwest Himalaya and adjoining regions using an earthquake catalog from India Meteorological Department covering a period from June 1, 1998 to June 30, 2011 has been carried out. The spatial distributions of seismicity parameters, namely magnitude of completeness, M C, a value, b value, and correlation fractal dimension, D C, are estimated for the studied region. The M C, a, and b values are found to be 2.5, 4.601, and 0.83, respectively. Despite significant gaps, the spatial distributions of a and b values are seen to follow similar trend and are found scattering in between Main Boundary Thrust (MBT) and South Tibet Detachment, adjoining areas of Mahendragarh-Dehradun Fault (MDF), Delhi-Haridwar Ridge (DHR) and Moradabad Fault (MF), and the southern flank of Karakoram Fault and Indus-Tsangpo Suture Zone. The estimated spatial distribution of b and a values is within 90 % of confidence level, thereby indicating non-uniform stress accumulation or higher rock fracturing density in the studied region caused by strong tectonization following several earthquakes. Negative correlation between low b value and high D C is observed predominantly in the region between the MBT and Munsiari Thrust or Main Central Thrust-I of Garhwal and Kumaon Himalaya, adjoining zones of MDF, DHR, and MF of Indo-Gangetic plain, and the eastern flank of the studied region, suggesting the presence of asperities in the zone. At the same time, active creeping process can be inferred in between the MBT and Main Central Thrust of Garhwal Himalaya and the surrounding areas of Shimla region of the Himalayan arc to the northwestern part of the studied region from the positive correlation between b value and D C. The results indicate that the structural heterogeneity caused by different stress accumulation and rock fracturing densities exists due to continuous tectonic adjustments between different geomorphic features of the studied region. An attempt has also been made to classify the studied region into smaller seismic zones by observing the spatial patterns of b value and D C that are fractal properties of the observed seismicity, along with the prevalent fault networks. 相似文献
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地质统计学是数学地质领域最为活跃而实用的分支,它是以区域化变量理论为基础,以变异函数为基本工具,研究那些在空间分布上既具有随机性又具有结构性的自然现象的科学。在第四纪研究中的很多特征(变量)均可看成区域化变量进行地质统计学分析。作者在讨论了经典概率论及数理统计方法简单地应用于第四纪研究可能出现的问题后,着重介绍了用于第四纪研究中的若干地质统计学方法及基本理论,同时,对地质统计学方法应用于第四纪研究中的前景进行了分析。 相似文献
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The use of the fractal dimension to quantify the morphology of irregular-shaped particles 总被引：3，自引：0，他引：3
For several decades, sedimentologists have had difficulty in obtaining an efficient index of particle form that can be used to specify adequately irregular morphology of sedimentary particles. Mandelbrot has suggested the use of the fractal dimension as a single value estimate of form, in order to characterize morphologically closed loops of an irregular nature. The concept of fractal dimension derives from Richardson's unpublished suggestion that a stable linear relationship appears when the logarithm of the perimeter estimate of an irregular outline is plotted against the logarithm of the unit of measurement (step length). Decreases in step length result in an increase in perimeter by a constant weight (b) for particles whose morphological variations are the same at all measurement scales (self-similarity). The fractal dimension (D) equals 1.0-(b), where b is the slope coefficient of the best-fitting linear regression of the plot. The value of D lies between 1.0 and 2.0, with increasing values of D correlating with increasing irregularity of the outline. In practice, particle outline morphology is not always self-similar, such that two or possibly more fractal elements can occur for many outlines. Two fractal elements reflect the morphological difference between micro-scale edge textural effects (D1) and macro-scale particle structural effects (D2) generated by the presence of crenellate-edge morphology (re-entrants). Fractal calibration on a range of regular/irregular particle outline morphologies, plus examination of carbonate beach, pyroclastic and weathered quartz particles indicates that this type of analysis is best suited for morphological characterization of irregular and crenellate particles. In this respect, fractal analysis appears as the complementary analytical technique to harmonic form analysis in order to achieve an adequate specification of all types of particles on a continuum of irregular to regular morphology. 相似文献
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辽河科尔康油田断裂分形特征与油气关系 总被引：14，自引：1，他引：13
本文运用分形理论对张强凹陷科尔康油田沙海组下段顶(T1)、九佛堂组顶(T2)和义县组顶(T3)3个反射层断裂系统的分布特征进行了研究,发现在标尺范围(8-0.5cm)内断裂系统具有良好的统计自相似性,不同的研究对象具有不同的分维值(D),而分维值的大小体现了断裂系展布的复杂性。断裂的规模、数目及在相同标尺下的面密度直接影响数盒子数法计算的分维值,不同子区域断裂系统的分维值D与其断裂所占断裂总数的百分比呈良好的正相关关系。不同储集类型的子区域对比表明,东区沙海组下段顶(T1)分维值高于西区,而西区义县组顶(T3)分维值高于东区。与油田已知油气分布特征对比后,发现并证实油田内子区域分维值大,油田丰度(含油面积或流体产能)就大。含油气盆地这种内在对应关系,为研究油气聚集和分布规律、评价和预测油气田提供了一种新思路. 相似文献
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Quantification of Aperture and Relations Between Aperture,Normal Stress and Fluid Flow for Natural Single Rock Fractures 总被引：1，自引：0，他引：1
Pinnaduwa H. S. W. Kulatilake Jinyong Park Pirahas Balasingam Robert Morgan 《Geotechnical and Geological Engineering》2008,26(3):269-281
Accurate quantification of rock fracture aperture is important in investigating hydro-mechanical properties of rock fractures.
Liquefied wood’s metal was used successfully to determine the spatial distribution of aperture with normal stress for natural
single rock fractures. A modified 3D box counting method is developed and applied to quantify the spatial variation of rock
fracture aperture with normal stress. New functional relations are developed for the following list: (a) Aperture fractal
dimension versus effective normal stress; (b) Aperture fractal dimension versus mean aperture; (c) Fluid flow rate per unit
hydraulic gradient per unit width versus mean aperture; (d) Fluid flow rate per unit hydraulic gradient per unit width versus
aperture fractal dimension. The aperture fractal dimension was found to be a better parameter than mean aperture to correlate
to fluid flow rate of natural single rock fractures. A highly refined variogram technique is used to investigate possible
existence of aperture anisotropy. It was observed that the scale dependent fractal parameter, K
v, plays a more prominent role than the fractal dimension, D
a1d, on determining the anisotropy pattern of aperture data. A combined factor that represents both D
a1d and K
v, D
a1d × K
v, is suggested to capture the aperture anisotropy. 相似文献
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P. Sengupta S. K. Nath K. K. S. Thingbaijam S. Mistri 《Journal of the Geological Society of India》2011,78(3):226-232
The seismicity of a region is implicit of the causal faulting mechanisms and geodynamic diversity of the subsurface regime
nucleating earthquakes of different magnitudes, several of which may be as devastating as ones historically reported in global
perspective of tectonic complexity as in the case of India. Fractal analysis using box-counting method for the major fault
networks across the country estimates fractal dimension, Df, values to be varying between 0.88 and 1.36. The fault segments in parts of northwest Himalayas, northeast India and Indo-Gangetic
plains, are observed to be associated with higher Df values implicating high seismicity rates. On the other hand, low Df values in the peninsular India indicate isolated pattern of the underlying faults. The fractal dimension is observed to be
indicative of predominant faulting types — higher values conforming to thrust faulting mechanism while lower to strike slip
tectonism. 相似文献