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- Arnold, André, et al.
(författare)
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Centrifuge modelling of the behaviour of flexible raft foundations on clay and sand
- 2010
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Ingår i: Physical Modelling in Geotechnics. - 9780415592895 ; , s. 679-684
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Konferensbidrag (refereegranskat)abstract
- In recent decades, foundations used for housing constructions changed from strip foundations to flexible rafts including the whole ground floor. Strip foundations were usually calculated with the assumption of an even stress distribution, and this is often applied to modern flexible raft foundations. The result of these calculations does not represent reality and may often lead to inappropriate design and unexpected structural damage. Physical model tests have been carried out to study the stress distribution on different foundation types on a variety of soils, and under various loading scenarios. A better understanding of the stress distribution between foundation and soil is possible due to normal stress measurements at the interface. For working loads, a clear difference in stress transfer between foundation and clay and sand soils could be observed while a change in depth of soil or shallow inclined bedrock has less effect on the stress distribution at the interface. © 2010 Taylor & Francis Group, London.
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- Bowman, Elisabeth T., et al.
(författare)
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Debris flows in a geotechnical centrifuge
- 2006
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Ingår i: Physical Modelling in Geotechnics, 6th ICPMG'06. - 041541587X - 9780415415873 ; , s. 311-316
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Konferensbidrag (refereegranskat)abstract
- A new apparatus to allow the examination of laboratory debris flows at prototype stress levels within a geotechnical drum centrifuge is described. The apparatus consists of a curved aluminium flume that lies within the circumference of the drum, the inclination of which can be altered from 0 to 40 degrees. PPTs may be placed in the base and along one aluminium side wall, while the other wall is made from Perspex, to enable viewing of the flow during a test. A tube at the head of the flume enables flow materials to be introduced after preparation external to the centrifuge, while tests may be carried out with both fixed and erodible beds. A high speed camera is used to capture images of the flow during centrifuge flight. Initial tests suggest a maximum particle size of 4mmmay be introduced to the flow.The influence ofwater content and fluid viscosity is discussed. © 2006 Taylor & Francis Group, London.
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- Bowman, Elisabeth T., et al.
(författare)
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Experimental modelling of debris flow behaviour using a geotechnical centrifuge
- 2010
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Ingår i: Canadian geotechnical journal (Print). - 0008-3674 .- 1208-6010. ; 47:7, s. 742-762
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Tidskriftsartikel (refereegranskat)abstract
- Physical modelling of debris flows has been carried out in the geotechnical drum centrifuge at ETH Zürich. A new apparatus to model debris flows in the centrifuge is described. The apparatus permits the final reach of a typical debris flow to be modelled within the centrifuge, with unconsolidated material flowing down a slope to deposit as a fan around the drum. Experiments are described for both fixed base conditions and erodible bases. Tests to examine the verification (modelling) of models show that debris flow behaviour is governed mainly by friction and consolidation processes, although some resolution is required between flow behaviour downslope and flow arrest during runout. The results are compared with bulk parameters determined for field-scale debris flows. It is found that some important flow mechanisms, such as contact-dominated behaviour and high pore pressures, are developed that are closer to those developed at fieldscale than tests conducted at 1g. Velocity profiles for erodible beds are compared with a semi-empirical expression derived for experimental debris flows at 1g. Normalized velocity profiles are found to be in agreement; however, absolute velocities differ from those predicted. Scaling, the limitations of the apparatus, and potential for future work are discussed
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- Bowman, Elisabeth T., et al.
(författare)
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Geotechnical centrifuge modelling of debris flows
- 2007
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Ingår i: International Conference on Debris-Flow Hazards Mitigation. - 9789059660595 ; , s. 229-239
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Konferensbidrag (refereegranskat)abstract
- A granular debris flow may grow in size through erosion of its substrate, resulting in an increased hazard through greater mass, speed and runout. Exactly what governs the erosion potential of a particular flow is a matter of some debate, however, with apparently similar conditions producing very different entrainment behaviour. Some theories use an extension of sediment transport models that involve the removal of soil through a shear stress applied by the flow. However, comparison of field and laboratory-scale data suggests that other processes, such as undrained loading of the bed, are also likely to have influence at large scales. Hence properties of the bed need to be considered as well as the characteristics of the flow material. The modelling of erosion processes at laboratory scale is generally limited by the low stresses applied by the soil-water mixture at small scale. Modelling flows in a geotechnical centrifuge overcomes this problem by increasing the g-level, therefore allowing for correct prototype stress levels to be accounted for at small scale. This paper describes the development and use of a model debris flow apparatus on a geotechnical drum centrifuge at ETH in Zurich, Switzerland. Preliminary tests have been undertaken to compare fixed and erodible bed conditions - enabling erosion processes to be examined at prototype stress levels. © 2007 Millpress.
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| 8. |
- Kailey, P., et al.
(författare)
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Modeling Debris flow behavior in a geotechnical centrifuge
- 2011
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Ingår i: Italian Journal of Engineering Geology & Environment. - 1825-6635 .- 2035-5688. ; , s. 339-349
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examine the effect of flow massand moisture content on debris flow velocity, discharge,and runout using a series of smallscale flumetests in a geotechnical centrifuge. We found that anincrease in mass and an increase in moisture contentincreased peak velocity during down-slope movement.However, the effect of increased moisture contentis much more pronounced than that of increasedmass. The maximum cross-sectional area observeddid not depend on mass or moisture content, althoughmay have been affected by the flow rate entering thecentrifuge. Consequently, flow velocity largely determinedthe peak discharge of each flow. An increasein moisture content increased the mobility of the flowin terms of depositional area and runout. Further, therunout of the centre of mass of the flows appears tobe linearly related to the momentum of flow materialentering the flume.
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| 9. |
- Kailey, P., et al.
(författare)
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Modelling debris flow processes with a geotechnical centrifuge
- 2011
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Ingår i: International Conference on Debris-Flow Hazards Mitigation. - 9788895814469 ; , s. 339-349
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Konferensbidrag (refereegranskat)abstract
- In this paper, we examine the effect of flow mass and moisture content on debris flow velocity, discharge, and runout using a series of smallscale flume tests in a geotechnical centrifuge. We found that an increase in mass and an increase in moisture content increased peak velocity during down-slope movement. However, the effect of increased moisture content is much more pronounced than that of increased mass. The maximum cross-sectional area observed did not depend on mass or moisture content, although may have been affected by the flow rate entering the centrifuge. Consequently, flow velocity largely determined the peak discharge of each flow. An increase in moisture content increased the mobility of the flow in terms of depositional area and runout. Further, the runout of the centre of mass of the flows appears to be linearly related to the momentum of flow material entering the flume. © 2011 Casa Editrice Università La Sapienza.
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| 11. |
- Sissakian, Varoujan K., et al.
(författare)
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Tectonics and Neotectonics of the Mesopotamian Plain : A Critical Review
- 2020
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Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - UK : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 10:4, s. 57-86
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Tidskriftsartikel (refereegranskat)abstract
- The Mesopotamian Plain is a part of the Mesopotamia Foredeep of the Zagros Foreland Basin and is a part of the Zagros Fold – Thrust Belt. The plain covers the central part of Iraq and extends south eastwards. It is a large continuously subsiding basin since the Upper Miocene (11.62 Ma). The plain is covered by thick Quaternary sediments of the Tigris and Euphrates rivers with their tributaries and distributaries. Therefore, the plain shows no structural features on the surface, except a main fault escarpment that extends from south of Al-Najaf city to south of Nasiriya city representing part of Abu Jir Active Fault Zone. However, the rolling topography, in the northern parts of the plain indicates subsurface anticlines that are still growing up, such as Balad, Samarra, Tikrit and Baiji anticlines. Moreover, many buried subsurface anticlines are present in different parts of the plain. All are growing anticlines and have caused continuous shift to the Tigris and Euphrates River and their distributaries indicating Neotectonic activities. The minimum and maximum subsidence amounts in the plain are zero and – 2500 m, respectively.
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