Study For Analysis Method Of Rockmass Discontinuities Based On High-Resolution Digital Borehole Images

Discontinuities within rockmass are very important to geotechnical stability, whenas it's difficult to find out the true distribution of these discontinuities in regular exploration geophysics. The digital panoramic borehole camera system (DPBCS), which was designed to describe borehole wall structure specially is able to acquire the data of discontinuities from borehole images in detail, such as attitude (orientation, strike and aperture), depth and so on. Thus studying on rockmass discontinuities based on high resolution digital panoramic borehole images is a new domain and of a certain theoretical and practical significance. This paper is to establish useful and convenient discontinuities analysis methods by summarizing characteristic borehole images characteristics. As mentioned in much literature, borehole images analysis methods only stayed in simple mathematical statistical analysis or tied in the use of other exploration geophysics methods. So that this paper points from the structure information of single-hole drilling by analyzing sinusoidal curve morphological characteristics to muti-hole discontinuities connectivity information using similarity analysis method. The main research work is as follows:(1) All research begains with digital borehole images. This paper summarizes a number of borehole images acquisition methods and principles, describes how to acquire the main parameters of discontinuities from unfold panoramic images. Besides, this paper introduces digital image processing techniques to enhance the solution of fuzzy images produced during original testing process in order to highlight some of the fracture images. The methods are listed as follows: (a) adjusting intensity (brightness and contrast); (b) equalizing image histogram; (c) filters processing, such as lowpass, highpass, sharpen and median; (d) edge detection, such as Roberts, Sober, Laplace and Variance. Some tests with borehole-wall images are carried on to determine the effective image enhancement method for better quality.(2) In this paper, a new sinusoid morphological description method is discussed in detail. As can be proved, the intersection curve unfolded along any point is a standard sine curve when a oblique planar discontinuity is intersected the borehole. As a starting point, the author summarizes the sinusoidal curve description method of the structure plane after analyzing nearly 1,000 discontinuities images and their sine curve morphological characteristics of geological phenomena appeared in images.Taking this approach, geological phenomena can be attributed to four features : interfaces, texture, fractures, and non-planar features, and the author give an example to illustrate its simple and practical.(3) Study of muti-hole discontinuities connectivity analysis methods. Statistics of structure planes within single-hole are non regularity, while studying comprehensive analysis of muti-hole discontinuities connectivity in borehole region could be within the law. In this paper , the author has computed the structure planes extension based on the analysis of muti-hole discontinuities connectivity and come to conditions which the structure planes within two neighboring boreholes intercut by each other should meet to. Furthermore, the author first introduces the concept of discontinuities similarity and proposes that two discontinuities which are similar can be connected with a straight line. The similarity of discontinuities images includes position analysis and rockmass environment analysis. The author has accomplished the parameters selection of the similarity analysis, introduced a similarity description function, proposed the methods to achieve the analysis, and given an example to prove it.