| 1. |
- Najser, Jan, et al.
(författare)
-
Mechanisms controlling the behaviour of double-porosity clay fills : in situ and centrifuge study
- 2010
-
Ingår i: Quarterly journal of engineering geology and hydrogeology. - : Geological Society of London. - 1470-9236 .- 2041-4803. ; 43:2, s. 207-220
-
Tidskriftsartikel (refereegranskat)abstract
- Two instrumented embankments built on a double-porosity landfill of clayey lumps were monitored in situ and modelled in a geotechnical drum centrifuge. Field measurements of hydrostatic levelling, depth reference points and pore pressure gauges showed high and variable compressibility of the landfills. Introductory modelling in a mini-centrifuge, combined with oedometer testing, demonstrated the key mechanisms in the double-porosity fills: irreversible deformation at low stress ranges as a result of rearrangement of the lumps, and reversible deformation (swelling) at higher stresses, similar to the behaviour of reconstituted material. Placing fill under water resulted in high initial void ratios followed by large deformations while loading. Dry filling followed by saturation may be recommended for further development of the landfills in future. Data from the geotechnical centrifuge models confirmed that permeability was controlled by the complex structure of the clay fills. Similarly to the field measurements, there were significant initial settlements on loading as a result of compression of open macro-voids. The double-porosity structure in the fresh fill allowed excess pore pressures to dissipate quickly, which accelerated the consolidation process initially. Thereafter, dissipation was controlled by the permeability of the intragranular pores in the clay, once the intergranular pores had closed
|
|
| 2. |
- Fäh, Donat, et al.
(författare)
-
Coupled seismogenic geohazards in Alpine regions
- 2012
-
Ingår i: Bollettino di Geofisica Teorica ed Applicata. - 0006-6729. ; 53:4, s. 485-508
-
Tidskriftsartikel (refereegranskat)abstract
- COupled seismogenic GEohazards in Alpine Regions (COGEAR) is an interdisciplinary natural hazard project investigating the hazard chain induced by earthquakes. It addresses tectonic processes and the related variability of seismicity in space and time, earthquake forecasting and short-term precursors, and strong ground motion as a result of source and complex path effects. We study non-linear wave propagation phenomena, liquefaction and triggering of landslides in soil and rock, as well as earthquake-induced snow avalanches. The Valais, and in particular parts of the Rhone, Visper, and Matter valleys have been selected as study areas. Tasks include detailed field investigations, development and application of numerical modeling techniques, assessment of the susceptibility to seismically induced effects, and installation of different monitoring systems to test and validate our models. These systems are for long-term operation and include a continuous GPS and seismic networks, a test installation for observing earthquake precursors, and a system to study site-effects and non-linear phenomena in two test areas (Visp, St. Niklaus / Randa). Risk-related aspects relevant for buildings and lifelines are also considered
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Pooley, Emma J., et al.
(författare)
-
Centrifuge modelling to compare ground improvement techniques on double porosity clay landfills
- 2009
-
Ingår i: Geotechnics of Soft Soils - Focus on Ground Improvement. - 9780415475914 ; , s. 281-285
-
Konferensbidrag (refereegranskat)abstract
- The ETH geotechnical drum centrifuge was used to model ground improvement on soft double porosity clay. Ground improvement was carried out in-flight and the techniques tested were dynamic compaction and an array of stone columns. Foundation tests on improved soil models showed that stone columns were more effective at increasing subsoil resistance at higher load. This may be because stone columns improve drainage of the clay layer and thus allow the clay itself to become stiffer. © 2009 Taylor & Francis Group.
|
|
| 7. |
|
|
| 8. |
- Abbasiverki, Roghayeh
(författare)
-
Analysis of underground concrete pipelines subjected to seismic high-frequency loads
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Buried pipelines are tubular structures that are used for transportation of important liquid materials and gas in order to provide safety for human life. During an earthquake, imposed loads from soil deformations on concrete pipelines may cause severe damages, possibly causing disturbance in vital systems, such as cooling of nuclear power facilities. The high level of safety has caused a demand for reliable seismic analyses, also for structures built in the regions that have not traditionally been considered as highly seismically active. The focus in this study is on areas with seismic and geological conditions corresponding to those in Sweden and Northern Europe. Earthquakes in Sweden for regions with hard rock dominated by high-frequency ground vibrations, Propagation of such high-frequency waves through the rock mass and soil medium affect underground structures such as pipelines.The aim of this project is investigating parameters that affect response of buried pipelines due to high-frequency seismic excitations. The main focus of the study is on reinforced concrete pipelines. Steel pipelines are also studied for comparison purposes. The effects of water mass, burial depth, soil layer thickness and non-uniform ground thickness caused by inclined bedrock are studied. The results are compared to those obtained for low-frequency earthquakes and the relationship between strong ground motion parameters and pipelines response is investigated. It is shown that, especially for high frequency earthquake excitations, non-uniform ground thickness due to inclined bedrock significantly increase stresses in the pipelines. For the conditions studied, it is clear that high-frequency seismic excitation is less likely to cause damage to buried concrete pipelines. However, the main conclusion is that seismic analysis is motivated also for pipelines in high-frequency earthquake areas since local variation in the ground conditions can have a significant effect on the safety.
|
|
| 9. |
- Abdullah, Mukhalad, et al.
(författare)
-
Floods and Flood Protection in Mesopotamia
- 2020
-
Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - UK : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 10:4, s. 155-173
-
Tidskriftsartikel (refereegranskat)abstract
- Mesopotamia is a land where floods have occurred very frequently. Many destructive floods had been registered by historians, who noted also the food control schemes used in those times. Over history, many structures were built and managed, but this work was taken up again by the General Directorate of Irrigation which was formed in 1917 to manage floods and reduce as much as possible losses, in addition to the development of irrigation works. Plans were made to build a sophisticated flood control and protection system. Several projects were proposed, and since the 1950s they were successfully implemented. Many multipurpose dams were built to mitigate flood conditions in addition to their other functions, such as Mosul Dam, Dokan Dam, Derbendikhan Dam and Haditha Dam. Other projects which were solely planned for flood protection include developing and using natural depressions such as Habbaniyah Lake on the Euphrates River and Tharthar Lake on the Tigris River, to protect Mesopotamia from floods. Moreover, the southern marshes in lower Mesopotamia may be utilized for flood protection. This paper deals only with these natural depressions leaving the dams at the time being.
|
|
| 10. |
- Abdullah, Mukhalad, et al.
(författare)
-
Irrigation Major Systems on Euphrates River within Mesopotamia
- 2020
-
Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - UK : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 10:4, s. 199-219
-
Tidskriftsartikel (refereegranskat)abstract
- Euphrates River is one of the two rivers where the civilization and irrigation had started, many major irrigation systems are still operating for centuries. The most important advancement of irrigation within this area happened after 1920s, where new structures were constructed, new canals excavated, new pumps installed, and salt affected lands were reclaimed. The major irrigation projects in along the reach of Euphrates within Mesopotamia are, Great Abu Ghraib, Great Musayab, Hilla Branch projects, Kifl-Shiniafiyah, in addition to many other medium and small size projects. Besides, some important Barrages have been built for controlling water levels of the Euphrates for proper operation, such as Fallujah and Hindiya Barrages. There is a great need for more reclamation in the lower parts of this territory, as well alternatives are needed to avoid discharging saline drainage water to the Euphrates in some projects.
|
|
