| 1. |
- Aad, G, et al.
(author)
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- 2015
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swepub:Mat__t
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| 2. |
- Bäckström, Ann, 1976-
(author)
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Rock damage caused by underground excavation and meteorite impacts
- 2008
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Doctoral thesis (other academic/artistic)abstract
- The intent of this thesis is to contribute to the understanding of the origin of fractures in rock. The man-made fracturing from engineering activities in crystalline rock as well as the fracturing induced by the natural process of meteorite impacts is studied by means of various characterization methods. In contrast to engineering induced rock fracturing, where the goal usually is to minimize rock damage, meteorite impacts cause abundant fracturing in the surrounding bedrock. In a rock mass the interactions of fractures on the microscopic scale (mm-cm scale) influence fractures on the mesoscopic scale (dm-m scale) as well as the interaction of the mesocopic fractures influencing fractures on the macroscopic scale (m-km scale). Thus, among several methods used on different scales, two characterization tools have been developed further. This investigation ranges from the investigation of micro-fracturing in ultra-brittle rock on laboratory scale to the remote sensing of fractures in large scale structures, such as meteorite impacts. On the microscopic scale, the role of fractures pre-existing to the laboratory testing is observed to affect the development of new fractures. On the mesoscopic scale, the evaluation of the geometric information from 3D-laser scanning has been further developed for the characterisation of fractures from tunnelling and to evaluate the efficiency of the tunnel blasting technique in crystalline rock. By combining information on: i) the overbreak and underbreak; ii) the orientation and visibility of blasting drillholes and; iii) the natural and blasting fractures in three dimensions; a analysis of the rock mass can be made. This analysis of the rock mass is much deeper than usually obtained in rock engineering for site characterization in relation to the blasting technique can be obtained based on the new data acquisition. Finally, the estimation of fracturing in and around two meteorite impact structures has been used to reach a deeper understanding of the relation between fracture, their water content and the electric properties of the rock mass. A correlation between electric resistivity and fracture frequency in highly fractured crystalline rock has been developed and applied to potential impact crater structures. The results presented in this thesis enables more accurate modelling of rock fractures, both supporting rock engineering design and interpretation of meteorite impact phenomena.
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| 3. |
- Lanaro, Flavio, et al.
(author)
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Characterisation of size, shape and texture of aggregates by fourier analysis of 3-D-laser images
- 2018
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In: ISRM International Symposium 2000, IS 2000. - : International Society for Rock Mechanics.
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Conference paper (peer-reviewed)abstract
- A new method for analysis of size, shape and roughness of aggregates based on a 3-D-laser-digitising technique is presented. Measurements of aggregate particles are carried out by a system consisting of a laser sensor and a co-ordinate-measuring machine; the accuracy of the system is ±50 µm. Scanned data are processed to create a digital image of aggregates to be employed in further analyses. Size, shape and volume analysis of particles has been conducted in two ways. A so-called geometrical analysis is based on simple applications of analytical geometry. Another method consists of the Fourier transform analysis of the topography of the two halves of the sample defined by a plane intersecting its mass center. Three-dimensional spectra are obtained as a function of two frequencies along the co-ordinate axes. The cross-sections of the spectrum are then investigated and the pattern of the power spectra gives the dimensions and shape of the particles. When comparing the results from these two methods, a very good agreement is obtained. From the spectrum, the texture component can be identified, which gives the roughness of the particles' surfaces. The new technique by Fourier transform analysis is promising giving repeatable results and performing a combined shape-size-texture analysis of the aggregate particles. .
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