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Zekai Şen 《Arabian Journal of Geosciences》2014,7(7):2915-2922
Rock quality designation (RQD) is a simple and effective way of rock mass classification from surface scanlines or preferably borehole measurements. A major drawback in its classical use is that only one representative RQD value is obtained from the field measurements per core run. However, it is shown in this paper that the field measurements along a scanline provide detailed information about the rock quality and the fracture intensity (FI) for a given number of joints. In order to be able to extract the complete information concealed within the field data, the RQD-fracture index diagram concept is proposed and applied to actual field scanline measurements from England. The basis of the suggested procedure is to obtain a series of all possible RQD and FI values from given intact length measurements. This procedure provides additional information as to the local zones of heterogeneities within the rock mass and a new way of rock classification on the basis of the combined effects of RQD and FI. It is also possible to calculate percentages of different rock qualities within the same rock mass. 相似文献
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Hatem Gasmi Essaïeb Hamdi Nejla Bouden Romdhane 《Rock Mechanics and Rock Engineering》2014,47(4):1393-1409
Homogenization in fractured rock analyses is essentially based on the calculation of equivalent elastic parameters. In this paper, a new numerical homogenization method that was programmed by means of a MATLAB code, called HLA-Dissim, is presented. The developed approach simulates a discontinuity network of real rock masses based on the International Society of Rock Mechanics (ISRM) scanline field mapping methodology. Then, it evaluates a series of classic joint parameters to characterize density (RQD, specific length of discontinuities). A pulse wave, characterized by its amplitude, central frequency, and duration, is propagated from a source point to a receiver point of the simulated jointed rock mass using a complex recursive method for evaluating the transmission and reflection coefficient for each simulated discontinuity. The seismic parameters, such as delay, velocity, and attenuation, are then calculated. Finally, the equivalent medium model parameters of the rock mass are computed numerically while taking into account the natural discontinuity distribution. This methodology was applied to 17 bench fronts from six aggregate quarries located in Tunisia, Spain, Austria, and Sweden. It allowed characterizing the rock mass discontinuity network, the resulting seismic performance, and the equivalent medium stiffness. The relationship between the equivalent Young’s modulus and rock discontinuity parameters was also analyzed. For these different bench fronts, the proposed numerical approach was also compared to several empirical formulas, based on RQD and fracture density values, published in previous research studies, showing its usefulness and efficiency in estimating rapidly the Young’s modulus of equivalent medium for wave propagation analysis. 相似文献
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不连续间距对岩体性质具有十分重要的意义。基于无限长测量线得到的岩体不连续间距的负幂指数分布是最重要的一种概率分布密度, 为纠正因用有限长测量线而带来的不连续间距的分布误差, 本文提出了一个封闭形式的修正函数。结果表明, 该法可显著减少不连续间距的相对误差, 从而可以采用较短的测量线来测量岩体的不连续间距。 相似文献
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It is not the purpose of this paper to propose a new rock mass classification system but rather to improve the existing ones by incorporating some simple quantitative interpretations. The geomechanics classification system of naturally fractured rock masses is modified to decrease personal judgement involved in its calculation. Instead of six parameters in the classical rock mass rating (RMR) system, only five basic parameters are considered in the proposed system, which are namely, rock quality designation (RQD) value with the underlying frequency distribution function of intact lengths; uniaxial or point load strength of intact rock material; conditions of the most unfavorable joints; groundwater condition; and joint orientation. Classical lump-rating system is replaced by continuous grading system which leaves no ambiguity for an inexperienced engineer in allocating grades based on quantitative field or laboratory measurements. Finally, necessary charts are presented for obtaining straightforward design values concerning average stand-up time and corresponding unsupported span of excavations in fractured rock mass; cohesion as well as friction angle of the rock mass. The continuous RMR system is very convenient for calculators or in writing computer software. The proposed methodology reduces the scale of subjectivity and leads to a unique rock mass design value. 相似文献
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Zekâi Sen 《Mathematical Geology》1984,16(5):449-463
Fundamentals of autorun analysis have been given to describe porous media geometry, including sedimantary rocks. The mathematical abstraction of porous media has been presented on the basis of random fields. Classical parameters of porous media, such as porosity and specific surface, have been expressed in terms of autorun function. Finally, a stochastic model has been proposed for the underlying generating mechanism of the porous medium. This model is capable of producing synthetic porous medium and, on the average, porosity as well as the specific surface. The first autorun coefficient is asymptotically equal to the porosity of the medium concerned. It also has been observed that the porosity together with the autorun function are sufficient to produce the specific surface value of the medium.On leave from the Technical University of Istanbul, Taksim, Turkey. 相似文献
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Rock Mass Rating (RMR) measurements from 65 sites within Huntly East underground coal mine are presented. All measurements are in coal, for which the dominant discontinuities are vertical cleat. Basic RMR values using two discontinuity spacings are presented: overall RMR based on the average spacing of all individual discontinuities; and cleat zone RMR based on the average spacing between zones of cleat. Cleat orientations are highly variable, but on average approximately parallel horizontal stress axes (face cleat follows maximum horizontal stress axis, butt cleat follows minimum horizontal stress axis).Contours of RMR variations throughout the mine are used to compare rock mass conditions with geological structure. It is apparent that: (1) RMR is least within downthrown fault blocks, and particularly immediately on the downthrown sides of faults, and greatest in upthrown fault blocks; and (2) RMR contours parallel horizontal stress axes within fault-bounded blocks, and bend to parallel faults at block boundaries. From similar contours for parameters contributing to RMR, the Rock Quality Designation (RQD), groundwater rating, and discontinuity condition rating create most of the observed variations in RMR. RQD is determined from the measured discontinuity frequency and hence is a measure of the degree of fracturing of the rock mass. This is interpreted as influencing the groundwater and condition parameters directly by allowing greater water ingress. Discontinuity frequency is greatest (least spacing) in the immediate vicinity of faults, and in downthrown fault blocks, generating low RMR values. Within fault blocks RQD varies little, so RMR contours align with cleat orientations.As RMR contours, faults, stress field and cleat orientation are clearly interrelated, there is unequivocally a connection between RMR and structural geology; this allows some predictive capacity in terms of ground conditions. If geological features can be accurately defined through either drilling programs or seismic surveys, then ground conditions may be predicted before panels are driven. 相似文献
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岩体结构特征的准确表征对边坡稳定性评价具有重要影响。由于高陡边坡岩体结构的人工编录工作开展困难,结构几何信息往往获取不全面,导致边坡数值模型构建往往不理想。以江西德兴银山铜矿露天边坡为工程背景,采用无人机与运动恢复结构法(SfM)获取边坡岩体点云模型。基于点云数据建立结构面识别和解译算法,自动获取结构面产状、迹长、间距等几何信息。对比人工测量结果,无人机测量与结构面识别能够获取更符合实际的坡面与岩体结构模型。采用非均匀有理B样条(NURBS)曲面重构和“Rhino-Griddle-3DEC”联合建模方法,结合岩体结构统计模型构建离散裂隙网络DFN能够快速建立三维离散元数值模型,从而获得更好的数值模拟计算结果,满足岩质高边坡稳定性评价的需要。 相似文献
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R. D. JACOBI 《《地质学报》英文版》2002,76(1):89-99
Semivariogram is applied to fracture data obtained from detailed scanline surveys of nine field sites in western New York, USA in order to investigate the spatial patterns of natural fractures. The length of the scanline is up to 36 m. How both fracture spacing and fracture length vary with distance is determined through semivariogram calculations. In this study, the authors developed a FORTRAN program to resample the fracture data from the scanline survey. By calculating experimental semivariogram, the authors found five different types of spatial patterns that can be described by linear, spherical, reversed spherical, polynomial I (for a<0) and polynomial II (for a>0) models, of which the last three are newly proposed in this study. The well-structured semivariograms of fracture spacing and length indicate that both the location of the fractures and the length distribution within their structure domains are not random. The results of this study also suggest that semivariograms can provide useful infor 相似文献
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结构面对工程岩体的强度及其稳定性起着关键作用。在工程选址时常会首先考虑花岗岩作为其地基或围岩,而钻孔揭露的是目标深度岩体最直接的数据。以广东深圳的大亚湾花岗岩体为例,结合地质背景,研究钻孔方向上结构面的分布规律。钻孔方向上花岗岩结构面主要为构造结构面和表生结构面。首先,对比沿钻孔方向花岗岩体中结构面与地表结构面的倾向与倾角,在同一场址区,受到同一构造作用影响,钻孔中与地表节理的产状分布类似。其次,研究沿钻孔方向结构面的间距（直接影响岩体的RQD值）,通过间距分组和回归分析,发现结构面间距与其频数具有明显的幂函数关系,且该关系式与RQD值相关。 相似文献
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本文针对结构面间距最常见的两种分布形式－－负指数分布和对数正态分布，探讨了岩石质量指标（RQD）的Monte-Carlo模拟方法，首和无根据结构面间距分布密度函数产和一包含50万个随机结构面并按生成顺序排列的模拟真实岩体的总测线，然后为了和实际 钻探时以2米测线计算RQD相一致，在总测线上按均匀分布形式随机抽取大于等于2米的局部测线共5万个计算RQD单值，并进一步统计得出所有RQD的平均值，RQD累积分布曲及岩石质量描述图，对于自然界大部分岩体，可根据结构面间距统计参数，直接在本文得出的一系列岩石质量图上定出RQD平均值，岩石质量百分比（RQP）及岩石质量风险（RQR）。 相似文献
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The following paper presents a new exploration technique called stereotomography. Such a technique appropriately combines stereograms with data from borecores or from drillhole logs. Its purpose will be to show graphically the general trends of data for structural domains, for sectors, or for a whole mine. This method has been originally designed for discrete RQD measurements between boreholes, but it also has many other uses when RQD is substituted by any other physical or geophysical parameter related to the rock mass. In their example case, the authors found that such a so-called stereotomographic technique, supported by a complete structural geology study, will be decisive in the choice of potential mining sites, since it can delimit the discontinuity attitudes present inside the rock mass. 相似文献
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Statistical analysis of some main geomechanical formulations evaluated with the Kaniadakis exponential law 总被引：1，自引：1，他引：0
Pierpaolo Oreste 《Geomechanics and Geoengineering》2018,13(2):139-145
The following paper reviews four well-known geomechanical equations, i.e. the elastic modulus of the rock mass as function of the Rock Mass Rating (RMR) system, the relation between Rock Quality Designation (RQD) and spacing distribution of the natural discontinuities in the rock mass, the distribution of the discontinuity spacing along a straight line for a rock mass and the intact rock strength in function of the specimen diameter by using a power-law flat tails equation based on the theory of Kaniadakis. The results show that by using novel formulations, the experimental data are better approximated by the power-law flat tails statistical approach, which shows a trend similar to ordinary exponential for a certain part of the interval of variability of x; the tails, however, follow the power law for extreme values of x. It was, therefore, possible to obtain new formulations able to better represent some fundamental aspects of geomechanics. 相似文献
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Characterising fractures at outcrop for use as analogues to fractured reservoirs can use several methods. Four important fracture data collection methods are linear scanline sampling, areal sampling, window sampling and circular scanline sampling. In regions of homogeneous fracture networks these methods are adequate to characterise fracture patterns for use as outcrop analogues, however where fractures are heterogeneous, it is more difficult to characterise fracture networks and a different approach is needed.We develop a workflow for fracture data collection in a region of heterogeneous fractures in a fold and thrust belt, which we believe has applicability to a wide variety of fracture networks in different tectonic settings. We use an augmented circular scanline method, along with areal sampling to collect a range of fracture attribute data, including orientation, length, aperture, spatial distribution and intensity. This augmented circular scanline method more than halves the time taken for data collection, provides accurate, unbiased data that is representative of local fracture network attributes and involves data collection of a wider range of fracture attributes than other sampling techniques alone. 相似文献
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选用三参数标准线性固体作为岩石本构,提出了一种考虑岩体黏弹性的位移不连续模型;根据一维黏弹性波的特征线法,推导了节理处质点速度、应力和应变递推公式。首先,基于分离式霍普金森压杆（SHPB）对砂层进行试验,得到其应力-应变关系,并换算出砂层节理的法向刚度;接着,通过一维强间断黏弹性波的波速公式、高频波衰减系数以及任一频率下的衰减系数,确定出数值算法中的三参数。最后,基于自制的摆锤装置,探讨了一维应力波在节理岩体中的传播规律,试验中以两根长1 000 mm、直径为68.50 m的岩杆作为入射和透射杆,以3 mm砂层模拟节理。试验和数值结果吻合度良好,进一步验证了该方法的可靠性。 相似文献
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Close-range terrestrial digital photogrammetry and terrestrial laser scanning for discontinuity characterization on rock cuts 总被引：9，自引：0，他引：9
This paper reviews the application of close-range terrestrial digital photogrammetry and terrestrial laser scanning for discontinuity characterization on rock cuts. Terrestrial remote sensing techniques are being increasingly used as a complement to traditional scanline and window mapping methods. They provide more comprehensive information on rock cuts, allow surveying of inaccessible outcrops, and increase user safety. Selected case studies are used to estimate the accuracy of several 3D model registration approaches and the most time-, effort- and cost-effective methods are highlighted. It is shown that simple registration networks are able to provide adequate measurement of discontinuity orientation for engineering purposes. The case studies presented also illustrate the effects of sampling bias and limitations related to discontinuity characterization using remote sensing techniques. Vertical orientation bias and occlusion can be of particular concern when persistent discontinuities dip at the same angle as the camera/scanner line-of-sight. Major advantages of the techniques are presented illustrating how terrestrial remote sensing techniques provide rapid spatial measurements of discontinuity location, orientation and curvature and are well suited to the quantification of persistence magnitudes greater than 3 m. 相似文献
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岩石质量指标(RQD)是评价岩体破碎程度的一个重要参数,但在RQD的应用过程中往往忽略测线长度和测线方向的影响,给岩体质量的评价造成一定的误差。笔者通过从野外岩石露头这个二维平面上得到的RQD或节理参数,推导得到在三维空间中任意方向测线的RQD,进而研究RQD随测线方向的变化规律。结果表明,RQD不但在平面上具有各向异性,在空间也具有各向异性。笔者提出了假定测线起于节理的N-A RQD计算模型,使理论论证更加严密。此外,利用蒙特卡罗模拟产生随机值代表节理间距,随机值服从负指数分布的参数不同代表节理发育的密集程度不同,通过T-T、N-A、A-A和A-A-S 4种RQD计算模型来研究RQD均值及标准差随测线长度的变化规律,可以得出：测线越长,所得RQD值越精确;测线较短时,A-A-S模型所得的RQD值与其他3种模型相比更精确;布置较长的测线在节理较发育的地方可获得更可信的RQD值。 相似文献
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变形模量作为表征岩体变形特征的重要参数,是岩体工程设计的基础力学参数之一。在综合前人研究的基础上提出了基于三维结构面网络模拟确定岩体变形模量的方法,编制了三维结构面网络模拟及计算RQD值的程序。以西南山区某水电站坝址区岩体为实例,在概率统计各组优势结构面几何要素分布形式的基础上,采用Monte Carlo法生成三维结构面网络模型,据此获得岩体三维RQD值,利用RMR法进行质量评价和变形模量的确定,并与钻孔资料统计法和原位试验结果进行对比分析。结果表明:基于钻孔资料统计的估算结果与原位试验相对误差达31.62%,且其估算值偏低;基于三维结构面网络模拟的估算结果与原位试验相对误差仅为2.56%,估算结果精度较高。该方法考虑了岩体质量的空间各向异性,对岩体的质量评价和参数确定更为合理,研究成果为该工程的优化设计提供了合理的计算参数。 相似文献
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采用渗流力学理论并结合Monte Carlo方法描述岩体裂隙的随机分布,研究渗流模型的尺寸效应并确定表征单元体积（REV）,得到了3种开口度分布形式的等效渗透系数椭圆曲线,建立了等效渗透系数方向性的判别标准。离散裂隙网络（DFN）模型假定流体只在岩体裂隙内部流动,而不通过岩体本身渗流。基于二维离散元程序UDEC并进行二次开发,建立DFN模型,通过改变流体的流动方向,得到不同流动方向下岩体裂隙网络的等效渗透系数,并分析不同的开口度分布形式对岩体裂隙网络等效渗透系数方向性的影响。计算结果表明,表征单元体积存在的条件是等效渗透系数保持稳定且渗透椭圆比较光滑。等效渗透系数的方向性受开口度分布形式的影响很大：当开口度-长度关联分布时,等效渗透系数各向异性;当开口度对数正态分布时,等效渗透系数各向同性;当开口度恒定分布时,等效渗透系数的特性介于二者之间。变化系数（CV）是否大于5%是判定岩体裂隙网络渗透系数是否具有方向性的判别标准。 相似文献