TA531 : The effect of liquefaction in depth on seismic ground motion
Thesis > Central Library of Shahrood University > Civil & Architectural Engineering > MSc > 2019
Authors:
Davoud Sheikh [Author], Amir Bazrafshan Moghaddam[Supervisor]
Abstarct: One of the most damaging phenomena caused by earthquakes is the phenomenon of soil lubrication. Soil lubrication during an earthquake results in loss of soil strength and hardness, which is more common in saturated sands. A saturated sand laxyer tends to condense and decrease in volume when exposed to dynamic load. If the pore water is not drained rapidly under dynamic loading, the pore water pressure will increase gradually if the pore water pressure increases to such a degree that the pore water pressure is increased. To be equal to the total stress, the phenomenon of liquefaction occurs. In fact, in this case the effective stress becomes zero and our sandy soil has no shear strength and acts as a fluid. Occurrence of liquefaction phenomena in soils and deposits, especially sandy soils, causes a wide range of damages, including subsidence and tilting of structures and foundations on the soil laxyer prone to liquefaction. In this study, Opensees software was used for modeling to evaluate soil interaction more accurately so that the user can come up with the principle of a software system by which the user can define model geometry, loading, quantitative structure, materials used, and analysis method by writing text. The dimensions of the soil profile are 50 m by 150 m and the analysis is 2-dimensional without overhead. The thickness of the wetland laxyer is assumed to be 3 meters and has been moved from the depth to the ground surface to investigate the effect of the wetland depth. For a constant depth, the thickness of the fluid laxyer was changed to 1, 3, and 5 m to show the effect of laxyer thickness on the outputs. The results showed that the farther from the surface, the higher the pore water pressure and the amount of sedimentation increased, but after a certain depth the amount of sedimentation no longer changed and the amount of ru increased and the maximum horizontal acceleration . baxsed on the results obtained in the study of thickness of the fluidized bed, it was found that by increasing the thickness of the wetland laxyer at a certain depth, by increasing the effective stress, the amount of pore water pressure increased. If the thickness of the wetland laxyer is 1 m, the saturation value will be highest, and as the thickness of the wetland laxyer increases, the maximum horizontal acceleration (indicated in the mapping acceleration) will be reduced to the surface. The thickness of one meter of the wetland laxyer at 3 meters depth causes a higher pore water pressure ratio than the 3 and 5 meter thickness of the wetland laxyer.
Keywords:
#Fluidization #Accelerogram #Opensees #Cavity Water Pressure Link
Keeping place: Central Library of Shahrood University
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