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Stephansson, Ove
Publications (4 of 4) Show all publications
Lanaro, F., Tolppanen, P., Illerström, A. & Stephansson, O. (2018). Characterisation of size, shape and texture of aggregates by fourier analysis of 3-D-laser images. In: ISRM International Symposium 2000, IS 2000: . Paper presented at ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000. International Society for Rock Mechanics
Open this publication in new window or tab >>Characterisation of size, shape and texture of aggregates by fourier analysis of 3-D-laser images
2018 (English)In: ISRM International Symposium 2000, IS 2000, International Society for Rock Mechanics , 2018Conference paper, Published paper (Refereed)
Abstract [en]

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. .

Place, publisher, year, edition, pages
International Society for Rock Mechanics, 2018
Keywords
Aggregates, Fourier analysis, Fourier transforms, Image analysis, Aggregate particles, Analytical geometry, Fourier transform analysis, Geometrical analysis, Repeatable results, Shape and textures, Texture analysis, Texture components, Particle size analysis
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-236438 (URN)2-s2.0-85053941193 (Scopus ID)
Conference
ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000
Note

QC 20181025

Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2018-12-04Bibliographically approved
Einstein, H. H. & Stephansson, O. (2018). Fracture systems, fracture propagation and coalescence. In: ISRM International Symposium 2000, IS 2000: . Paper presented at ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000. International Society for Rock Mechanics
Open this publication in new window or tab >>Fracture systems, fracture propagation and coalescence
2018 (English)In: ISRM International Symposium 2000, IS 2000, International Society for Rock Mechanics , 2018Conference paper, Published paper (Refereed)
Abstract [en]

In the context of "strength of rocks for rock slope design" this paper concentrates on the fact that rock masses are discontinua and, in many cases, have to be modelled as such. The paper, therefore, first describes various ways in which fracture systems can be described. Specifically, geometric, mechanical and geometric - mechanical models are discussed with emphasis on the latter. When considering slope stability, as well as rock mass behavior in general, it is very important to capture the mechanisms by which the discontinuities interact with each other. This interaction involves fracture coalescence which is the second major part of the paper. While all the preceding problems involve mainly non-persistent fractures, a few final comments are made on some special issues relating to persistent fractures. Throughout the paper we attempt to present the state-of-the-art of theory and compare it to the state of practice.

Place, publisher, year, edition, pages
International Society for Rock Mechanics, 2018
Keywords
Coalescence, Rock mechanics, Rocks, Slope stability, Fracture propagation, Fracture systems, Mechanical model, Rock mass, Rock mass behavior, Rock slope, State of practice, State of the art, Fracture
National Category
Mineral and Mine Engineering
Identifiers
urn:nbn:se:kth:diva-236450 (URN)2-s2.0-85053897426 (Scopus ID)
Conference
ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000
Note

QC 20181020

Available from: 2018-10-19 Created: 2018-10-19 Last updated: 2018-10-19Bibliographically approved
Su, S., Stephansson, O. & Peng, J. (2018). The effect of fracture pattern on in situ rock stresses studied by the distinct element method. In: ISRM International Symposium 2000, IS 2000: . Paper presented at ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000. International Society for Rock Mechanics
Open this publication in new window or tab >>The effect of fracture pattern on in situ rock stresses studied by the distinct element method
2018 (English)In: ISRM International Symposium 2000, IS 2000, International Society for Rock Mechanics , 2018Conference paper, Published paper (Refereed)
Abstract [en]

By using the two-dimensional distinct element method and the code UDEC, this study numerically models the effect of fracture pattern on rock stresses. Three geological fracture pattern models are considered: (1) two parallel fractures, (2) multiple parallel fractures and (3) intersecting fractures. For each model, the mechanical properties of intact rocks, strength parameters of the fractures, boundary stress ratio K (K=σ1/σ2) and the angle α between fracture and the direction of maximum boundary stress are varied. By placing profiles or points in the models to monitor stress variation across fractures in the models, the quantitative relation between fracture pattern and the magnitude and orientation of stresses has been derived numerically. As a result, stresses in the vicinity of fractures are determined.

Place, publisher, year, edition, pages
International Society for Rock Mechanics, 2018
Keywords
Stresses, Distinct element methods, Fracture pattern, Intersecting fractures, Parallel fractures, Quantitative relations, Strength parameters, Stress variations, Two-dimensional distinct element method, Fracture
National Category
Geophysical Engineering
Identifiers
urn:nbn:se:kth:diva-236364 (URN)2-s2.0-85053864621 (Scopus ID)
Conference
ISRM International Symposium 2000, IS 2000, 19 November 2000 through 24 November 2000
Note

QC 20181106

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
Jing, L. & Stephansson, O. (2005). Special Issue: Research results from the DECOVALEX III & BENCHPAR projects - Preface. International Journal of Rock Mechanics And Mining Sciences, 42(5-6), 591-592
Open this publication in new window or tab >>Special Issue: Research results from the DECOVALEX III & BENCHPAR projects - Preface
2005 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, no 5-6, p. 591-592Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
Royal Inst Technol, Grp Engn Geol & Geophys, S-10044 Stockholm, Sweden.: PERGAMON-ELSEVIER SCIENCE LTD, 2005
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-242478 (URN)10.1016/j.ijrmms.2005.03.020 (DOI)000231580700001 ()
Note

QC 20190205

Available from: 2019-02-05 Created: 2019-02-05 Last updated: 2019-02-05Bibliographically approved

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