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| 2. |
- Eitzenberger, Andreas
(författare)
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Inventory of geomechanical phenomena related to train-induced vibrations from tunnels
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Banverket is expecting that the number of railway tunnels in densely populated areas will increase over the next 20 years due to the lack of available space on the ground surface, but also since the railway is considered an environmentally friendly solution of transportation for the future. The need for good predictions of vibration and noise levels in dwellings along the planned tunnels is therefore evident. Due to lack of understanding of the propagation of train-induced vibrations from tunnels in rock a research project has been initiated by Banverket. This thesis constitutes the first stage of that project. In this thesis, the propagation of vibrations through a rock mass has been reviewed. The emphasis has been on wave propagation in hard rock masses. Areas, such as the generation of vibrations at the train-rail interface, the response of buildings and humans, national and international recommended noise and vibrations levels, and possible countermeasures are briefly reviewed as well. Finally, suggestions for the continued research are presented. The propagation of waves is influenced by attenuation along the propagation path. The attenuation can either be through geometric spreading, energy loss within the material, or reflection and refraction at boundaries. In a rock mass, where heterogeneities of various scales are present, the attenuation of (train-induced) waves through the ground therefore mainly depends on the properties of the discontinuities. Theoretical models of wave propagation across individual fractures have been presented in the literature. These models can be used to study the attenuation at the fracture for different combinations of joint stiffness, impedance, and angle of incidence. Also multiple parallel joints can be theoretically analysed. The attenuation of low-frequency waves is more prominent in weak rock masses and virtually negligible for hard rock masses. An increased amount of random oriented joints, faults and boundaries increases the attenuation of the waves, but is not possible to study with the aid of theoretical models. The rock mass is in most cases inhomogeneous due to all heterogeneities present. Despite this fact, the rock mass and soil is always treated as an isotropic, homogeneous material in the analyses of ground-borne noise and ground-borne vibrations. This concerns both numerical and empirical methods. Thus, there is a lack of a method that considers the influence of various heterogeneities present in a rock mass on the propagation of waves. Future research regarding train-induced vibrations should focus on combining the models of attenuation in the material with the models of attenuation across joints. Thereafter, conceptual models should be used to determine the propagation of low-frequency waves in a rock mass containing various amounts of heterogeneities (from isotropic to highly inhomogeneous) which should be compared to the theoretical methods available. Once the behaviour of waves in an inhomogeneous rock mass has been established, conceptual models should be used together with measurements from a few well documented cases. From the results of the analysis, guidelines for analysis of railway tunnels with regard to ground-borne noise and ground-borne vibrations should be established.
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| 3. |
- Eitzenberger, Andreas
(författare)
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Train-induced vibrations in tunnels : a review
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Banverket is expecting that the number of railway tunnels in densely populated areas will increase over the next 20 years due to the lack of available space on the ground surface. Together with the increased awareness of the residents the need for good prediction of vibration and noise levels in dwellings along the planned tunnels is evident. Consequently, a study of the propagation of vibrations through rock and soil generated by trains operating in tunnels is required in order to make more reliable prognoses. This report constitutes the first stage within a research project aimed at increasing the understanding about ground-borne noise and ground-borne vibrations generated by trains moving in tunnels constructed in rock. In this report, the propagation of vibration through a rock mass is reviewed. The emphasis has been on wave propagation in hard rock, but soil has also been included. Areas, such as the generation of vibration at the train-rail interaction, the response of buildings and humans, national and international recommended noise and vibrations levels, measurement of noise and vibrations, and possible countermeasures are briefly reviewed as well. Finally, suggestions for the continued research within this field are presented. The propagation of waves is influenced by attenuation along the propagation path. The attenuation can either be through geometric spreading, energy loss within the material, or reflection and refraction at boundaries. In a rock mass, where heterogeneities of various scales are present, the attenuation of (train-induced) waves through the ground therefore mainly depends on discontinuities, e.g. joints, faults, cracks, crushed zones, dykes, and boundaries between different rock types or soil. Also the topography - along as well as intersecting tunnels - influences the wave propagation in form of local amplification. An increased amount of joints, faults and boundaries increases the attenuation of the waves. The rock mass is in most cases inhomogeneous due to all heterogeneities present. Despite this fact, the rock mass and soil is always treated as an isotropic, homogeneous material when analyzed with regard to ground-borne noise and ground-borne vibrations. This concerns both numerical and empirical methods. Thus, there is a lack of knowledge regarding the influence of various heterogeneities on the propagation of waves, and thereby vibrations, in non-isotropic ground conditions (e.g. a rock mass) at low frequencies. Future research regarding train-induced vibration should focus on conceptual models used to determine the propagation of low-frequency waves in a rock mass containing various amount of heterogeneities (from isotropic to highly inhomogeneous). Once the behaviour of waves in an inhomogeneous rock mass has been established, conceptual models should be used together with measurements from a few well documented cases. From the results of the analysis, guidelines for analysis of railway tunnels with regard to ground-borne noise and ground-borne vibrations should be established.
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| 4. |
- Miskovsky, Karel, et al.
(författare)
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Influence of the mineralogical composition and textural properties on the quality of coarse aggregates
- 2004
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Ingår i: Journal of materials engineering and performance (Print). - : Springer Science and Business Media LLC. - 1059-9495 .- 1544-1024 .- 0000-0000. ; 13:2, s. 144-150
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the influence of the petrographic variables on the quality of coarse aggregates consisting of granitoid (granite to tonalite) rocks, 17 samples selected from the Swedish part of the Baltic shield have been studied concerning their petrographic properties, for example, mineral composition, grain size, grain boundaries, and the frequency of micro-cracks. All of the samples selected also have been studied in mechanical tests used to evaluate the quality of aggregates in Sweden. The quality has been determined by means of flakiness, impact value, abrasion value I, and abrasion value II. An analysis of the influence of the mineral composition and textural properties on the aggregate quality has been performed using statistical correlation and linear models. The results indicate that an increasing content of feldspar negatively influences the strength against impact, while an increasing content of mica (tested to 35 vol.%) combined with a diminishing grain size and more irregular grain boundaries has a positive influence on the resistance of granitoids to mechanical impact. Abrasion value II seems to be mainly influenced negatively by an increasing frequency of micro-cracks. The practical implementation of the results is suggested.
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| 5. |
- Hintze, Staffan, et al.
(författare)
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Effektivare hantering av geotekniska risker i infrastrukturprojekt
- 2006
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Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; :2, s. 22-28
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Under de senaste årtionden har många infrastrukturprojekt blivit väsentligt dyrare och tagit längre tid att genomföra än beräknat. En stor del av projekten har dessutom orsakat kostsamma tvister för flera parter i projektet och för samhället. Kostnaderna för skador på grund av bristande hänsyn till de geotekniska faktorerna står för en betydande del av totalkostnaden.
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| 7. |
- Bernander, Stig
(författare)
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Progressive landslides in long natural slopes : potential extension and configuration of finished slides in strain-softening soils
- 2000
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A finite difference method is presented for progressive slides in long natural slopes. The method is based on a strain softening material model. A detailed worked out example is given as well as examples using a spread sheet PC program and a PC program for Windows. Several Scandinavian slides are analysed and discussed as case studies e g Tuve (1977), Surte (1951), Bekkelaget (1953), Rollsbo (1967), Rävekärr (1971), Tre-styckevattnet (1990) and Svärtaån (1938). The nature of down-slope progressive failures in natural slopes is described and the applicability of ideal-plastic failure analysis is questioned. Principles and procedures for investigation potential landslides are presented. A short historical background to the landslide problem is given in an introductory chapter.
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| 9. |
- Vikström, Lars, et al.
(författare)
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Strength and deformation behaviour of snow and snow structures : field and laboratory measurements at Icehotel Jukkasjärvi, Winter 2000 - 2001
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Density measurements, unconfined compression tests, creep tests, beam tests, and measurements of deformations were performed on snow and snow structures that formed the Icehotel during the winter 2000/2001. Results from the unconfined compression tests and creep tests showed that: At -5ºC unconfined compression strength was 0,598 MPa with a snow density of 532 kg/m3. Axial viscosity was 3,23·106 MPa-s and compactive viscosity was 5,24·106 MPa-s with a snow density of 524 kg/m3. At -10ºC unconfined compression strength was 0,681 MPa with a snow density of 558 kg/m3. Axial viscosity was 1,92·106 MPa-s and compactive viscosity was 1,38·106 MPa-s with a snow density of 518 kg/m3. At -11ºC unconfined compression strength was 0,879 MPa with a snow density of 550 kg/m3. Axial viscosity was 2,16·106 MPa-s and compactive viscosity was 2,79·106 MPa-s with a snow density of 470 kg/m3. Beam tests were performed on snow from a pile of artificially made snow. This type of snow was used to construct the arcs of the Icehotel. Results from the beam tests showed that the snow had a mean density of 510 kg/m3 and that Young's modulus E had a mean value of 335 MPa. At failure mean value of maximum tensile- and compression stress was 0,375 MPa and mean value of maximum shear stress was 0,039 MPa. During the winter 2000/2001 deformations of the church building were measured. Results show that the apex of the arcs actually rose 4 to 8 cm, though the shape of the arcs changed very little. Comparing results from this investigation with results from earlier investigations made on snow with similar densities showed that: Unconfined compression strength was 20 to 40 percent lower. Axial viscosity was similar in all but one test at -10/-11 ºC. Axial viscosity was in all tests higher at -5 ºC. Compactive viscosity was higher in all tests. Results from the beam tests regarding Young's modulus values and tensile strength showed similar results.
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| 10. |
- Semadeni-Davies, Annette, et al.
(författare)
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Northern Research Basins Preface
- 2005
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Ingår i: Proceedings of the 15th northern research basins international symposium and workshop. - Lund : Department of Water Resources Engineering, Lund University.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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