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岩体不连续面迹长、产状、空间组合形态等的不确定性和复杂性,使结构面整体几何形态研究存在困难。利用岩体内大量随机展布的不连续面所具有的统计相似性,结合具有统计意义的数学方法进行结构面参数描述,是岩体随机不连续面三维网络模拟的基础,也为岩体稳定性评价提供可靠依据。本文基于数字近景摄影测量技术对长春市净月开发区东升采石场坡面进行调查研究,获取高精度的大量岩体结构面迹长、产状、间距、张开度等几何参数。利用Matlab编制Kolmogorov-Smirnov（K-S）检验程序,实现结构面参数的K-S法概率分布检验,分析了结构面参数所服从的概率分布类型;同时用SPSS软件检验程序正确性,并引入最优拟合度,选取符合多种概率分布参数的最优拟合概率模型。结果表明：研究区内结构面迹长、间距服从对数正态分布规律,产状服从伽马分布规律。 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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裂隙率作为表征岩体裂隙特征的一项重要参数,有线裂隙率、面裂隙率、体裂隙率3种表征方法。目前常用测线法、统计窗法获取线、面裂隙率仅能从一维或二维反映裂隙发育情况,其方法还存在测量结果随机性、应用受出露条件所限等不足;现有体裂隙率测量方法也存在着实际应用性较差、成本高等问题,尚缺乏简便易操作的野外测量方法。为此本文提出了一种新的野外测量岩体体裂隙率的工作方法--球体法。由于构造、成岩裂隙发育的组系性、方向性,球体法根据各组裂隙产状从不同方向进行观测,通过多次测量统计岩体出露面上裂隙的发育特征,推断岩体内部裂隙的发育状况,其值能更好地反映局部区域岩体内部裂隙发育程度。此外,在测量时利用专利仪器可以得到沿裂隙面法线方向上隙宽以及隙间距数据真实值,测量条件对出露面平整情况要求不高,测量结果受露头平整性影响不大,具有更好的实用性。本文以安庆大龙山采石场研究区为例应用球体法,野外现场测量表明该方法可以在较为方便操作的基础上实现快速测量;研究区体裂隙率均值为2. 286%,集中分布在1%~4%,结合研究区实际情况以及误差分析结果,球体法可以很好地反映研究区各个测量点的裂隙发育程度。 相似文献
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岩体结构研究中统计区间长度的确定 总被引：5，自引：0，他引：5
岩体结构研究日益得到工程地质界的重视,而岩体结构面现场测量数据是获得岩体结构特征的必需资料。在目前常用的2种结构面测量方法中对如何选择合理的统计区间长度缺乏充分的论证。利用我国西南某大型水电工程丰富的结构面测量资料,研究统计区间长度对岩体结构类型的影响,取得了一定的成果。即最小有效测线长度与结构面间距大小及概率密度分布形式有关,研究岩体结构特征时,必须根据工程实际情况选择满足要求的统计区间长度。 相似文献
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岩体结构研究日益得到工程地质界的重视，而岩体结构面现场测量数据是获得岩体结构特征的必需资料。在目前常用的 2种结构面测量方法中对如何选择合理的统计区间长度缺乏充分的论证。利用我国西南某大型水电工程丰富的结构面测量资料，研究统计区间长度对岩体结构类型的影响，取得了一定的成果。即最小有效测线长度与结构面间距大小及概率密度分布形式有关，研究岩体结构特征时，必须根据工程实际情况选择满足要求的统计区间长度. 相似文献
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准确获取隧洞岩体结构面的几何信息对于隧洞的稳定性评价至关重要。研究区位于长春市净月潭吉林大学岩体力学隧洞实习基地。应用免棱镜全站仪进行岩体隧洞的控制测量,按照测量工作中"先控制后碎部"的基本原则,进行全站仪棱镜模式下的导线测量及在各导线点上极坐标法免棱镜模式的岩体结构面控制点测量;通过对同测站及异测站相同结构面控制点坐标数据的对比分析,探讨免棱镜全站仪测量方向与岩体结构面夹角的限差。研究表明:在隧洞控制测量中,免棱镜全站仪测量方向与结构面间夹角大于30°是准确获取岩体目标控制点坐标的必要条件之一。 相似文献
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Zekai en 《Mathematical Geology》2000,32(8):985-999
An important factor in the rock quality assessment analysis from discontinuity measurements along a scanline is the correlation of intact lengths. The autorun model and first order autorun coefficient are proposed as a method for objectively quantifying intact length correlation structure and discontinuity occurrences along any scanline. Necessary definitions for the methodology are presented on a quantitative basis such as the alternative intact length percentages and experimental autorun coefficient. An expression is proposed for the number of discontinuity occurrences along a scanline depending on the scanline length, alternate intact length percentages, and the autorun coefficient. Monte Carlo simulation technique is used with a suitable autorun model to verify this expression. A mathematical expression is derived for the expected Rock Quality Designation (RQD) value by taking into account the correlation of the intact lengths. Additional simulations show the validity of the new RQD expression. With the methodology proposed much less engineering experience and judgment are required in estimating the RQD value from scanline measurements. The application of the methodology has been presented for some field data. 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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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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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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Bias Correction for View-limited Lidar Scanning of Rock Outcrops for Structural Characterization 总被引：2，自引：0，他引：2
Matthew J. Lato Mark S. Diederichs D. Jean Hutchinson 《Rock Mechanics and Rock Engineering》2010,43(5):615-628
Lidar is a remote sensing technology that uses time-of-flight and line-of-sight to calculate the accurate locations of physical
objects in a known space (the known space is in relation to the scanner). The resultant point-cloud data can be used to virtually
identify and measure geomechanical data such as joint set orientations, spacing and roughness. The line-of-sight property
of static Lidar scanners results in occluded (hidden) zones in the point-cloud and significant quantifiable bias when analyzing
the data generated from a single scanning location. While the use of multiple scanning locations and orientations, with merging
of aligned (registered) scans, is recommended, practical limitations often limit setup to a single location or a consistent
orientation with respect to the slope and rock structure. Such setups require correction for measurement bias. Recent advancements
in Lidar scanning and processing technology have facilitated the routine use of Lidar data for geotechnical investigation.
Current developments in static scanning have lead to large datasets and generated the need for automated bias correction methods.
In addition to the traditional bias correction due to outcrop or scanline orientation, this paper presents a methodology for
correction of measurement bias due to the orientation of a discrete discontinuity surface with respect to the line-of-sight
of the Lidar scanner and for occlusion. Bias can be mathematically minimized from the analyzed discontinuity orientation data. 相似文献
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Summary The block sizes in a rock mass play an important role in many rock engineering projects and therefore the assessment of in-situ
block size distribution (IBSD) has been an increasing pursuit of researchers in mining, quarrying and highway cutting operations.
This paper discusses further developments in the assessment of IBSD which build upon a broadly accessible approach for engineers
published previously by the Geomaterials Unit. The original research provided look-up tables appropriate for field data, with
theoretical joint set spacing distributions and an assumption that discontinuities extend indefinitely. The developments reported
in the paper include: the prediction of IBSD with special reference to discontinuity sets with fractal spacing distributions;
the influence of impersistence of discontinuities on the prediction of IBSD; and the use of grey correlation analysis when
selecting a closely fitting theoretical distribution for discontinuity spacing data. Various approaches to IBSD assessment
are discussed. 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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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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Qingfa Chen Tingchang Yin Wenjing Niu Wenshi Zheng Junguang Liu 《Arabian Journal of Geosciences》2018,11(11):286
The determination of representative elementary volume (REV) is critical for mechanical model establishment and the determination of rock mass mechanical properties. Therefore, in this study, the REV range, existence, determinate parameter, and category were discussed. The blockiness level of the rock mass (Bz) was defined as the new index to determine the geometrical rock mass REV. Then, a great variety of multiscale three-dimensional fractured network models with different discontinuity persistences and spacings were developed. Finally, the Bz values of all models were measured, and the geometrical REVs were determined, the correlation between the geometrical REVs and rock mass discontinuity properties were assessed, and size validations of geometrical REVs were performed. In this study, it is shown that the REV is approximately 20–50 times that of the discontinuity spacing when the discontinuity spacing is classified as having extremely close to close spacing and is between approximately 0.3 and 4.0 times the discontinuity diameter when discontinuity spacing is in the range from moderate to extremely wide spacing. Further, there is a fourth-order nonlinear correlation between the geometrical REV and the ratio of the discontinuity diameter to discontinuity spacing. Meanwhile, the validation results confirm that the geometrical REV is slightly less than the sizes at which the elastic moduli tend to plateau, and the rationality of the geometrical REV of a rock mass based on Bz is thus supported from another perspective. 相似文献