摘要
岩体是地质体,其在构造过程中形成的裂隙是衡量岩体力学性能和渗透特性的关键因素。裂隙几何参数(包括产状、开度、迹长等)的获取,对岩体的力学性能和渗透特性研究分析来说十分重要。
传统的岩体裂隙信息的提取方法,是人工借助测量工具进行实地测量统计。该方法虽然原理简单,但是耗时低效而且受外界环境条件影响较大。相比之下,将数字近景摄影测量技术运用到岩体裂隙的测量和统计上来,具有快速、高效和信息量大等优点。
本文在前人研究的基础上,以金山店铁矿张福山矿区具代表性外露岩体为研究实例,运用数字近景摄影测量和数字图像处理技术,对岩体裂隙参数的快速提取方法进行了探讨和研究。其主要工作包括图像获取,图像纠偏,图像分析三个方面。
图像获取方面,在总结和对比已有数字图像采集方法的基础上,结合本文研究对象和其现场条件,选取二维正直投影方式,借助数码相机等工具获取了岩体结构面的数字图像。
图像纠偏方面,提出了一种新的纠偏方法来对二维数字图像进行整体几何纠偏。该方法包括确定岩体结构面控制点的三维坐标,将三维坐标转换至与图像空间对应的二维坐标,计算图像空间和实体空间之间的转换矩阵,图像重采样内插等步骤。并以一张岩体结构面的数字图像作为例子按该方法进行纠偏,以证明该方法的有效性。
图像分析方面,针对裂隙数字图像的复杂性,提出了一种基于半自动化检测识别技术的裂隙参数提取统计方法。该方法以已有的数字图像处理技术为理论基础,依次对岩体裂隙图像进行数字化、半自动化裂隙边缘检测识别、边缘坐标提取重生成二值图像、裂隙参数计算统计。上述过程以实际岩体裂隙图像为研究实例,运用MATLAB软件编程实现以图像的相关处理。最终得到了岩体结构面裂隙几何参数数据。
Rock masses naturally have several kinds of discontinuities, including the most common one, rock joint. The joints in rock mass is the crucial factor of rock stability and permeability. Therfore, to obtain geometric properties of joints in rock mass, such as orientation, aperture, and consistence etc, becomes a crucial impotant step in the process of rock mass analysis.
The traditional method for extracting geometric properties of joints on exposure of the rock mass is manual measuring with the help of measuring tools. Obviously, it is time-consuming, low effcient and sensitive to the external environment. By contrast, digital close photogrammetry can be more efficient in extraction of joints information.
After reffering the current literatures, this paper uses digital close range photogrammetry to acquire joints information from exposure of the rock mass, focusing on rapid extracting joints information on exposure of the rock mass. This study is carried out in Jinshandian Iron Mine, The content of research in this paper is mainly divided into three steps: image acquisition, geometric correction and image analysis statistical.
For image acquisition, based on the existing ways about method of digital image acquisition, a digital camera is used to collect digital image for exposure on the rock mass. By consideraing the research objectives in this paper and field conditions, a suitable method, two-dimensional normal projection method is selected as the image acquisition method.
In terms of geometric correction for digital image, a new geometric correction method in processing close range digital photograph is proposed. The correction method covers four main points, determing of control points on the exposure of the rock mass, converting the coordinate value on the exposure of rock mass into the plane coordinate value which correspond with digital image space, mathematically solving the transformation matrix, geometrically correcting and resampling the digital photograph. Detailes for the correction method are presented in the process of geometrically correcting the digital photograph taken from the outcrop of a rock mass in Jinshandian. From the illustrative example, it has been found that the geometric correction method is effective in processing close range digital photograph.
In respect of image analysis, by consideraing the complexity of the digital image from the exposure of rock mass, a semi-automated extraction and statistical method is proposed. The method includes image digitization, semi-automated detection and recognition for edge of joints edge, extracting edge coordinate values and redrawing binary image relation with joints, computing statistical data for joints parameters. MATLAB software is used in this process, and finally obtaining the statistical data for rock joints from the exposure on the rock mass. Detailes for the semi-automated extraction and statistical method are presented in the process of processing the same digital photograph taken from the outcrop of a rock mass in Jinshandian. It has been found that the method is fast and effective.
引文
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