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Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Modelling of excess pore pressure accumulation in sand around cyclically loaded foundations
In particular during storm events an accumulation of excess pore pressures may occur in the soil around cyclically loaded offshore foundations. The excess pore pressure build-up reduces the effective stresses in the soil and, hence, may negatively affect the structural integrity by influencing the soil-structure interaction. Besides a loss in bearing capacity, large plastic deformations may occur to the structure. Especially for offshore wind turbines an accurate estimation of such deformations is of great importance. Even though the consideration of this degradation effect on the bearing capacity is commonly demanded by the involved certification or approval bodies, no general applicable and accepted method for the calculative verification currently exists. Over the past decades several researchers investigated the excess pore pressure build-up around offshore foundations due to environmental cyclic loads. They tried to capture the loss of bearing capacity, the accumulation of plastic rotation and the essential influence on the serviceability limit state and fatigue design. However, even if there are some sophisticated concepts, none of them is seen as the simple general applicable choice. Within this thesis a new numerical method – termed Excess Pore Pressure Estimation method (EPPE) – is presented in great detail. This method allows for the transfer of the soil behaviour obtained in cyclic simple shear tests to the bearing behaviour of the entire foundation. Herein, the numerical model accounts for the cyclic excess pore pressure accumulation by respecting the element-based mean stress and stress amplitude as well as an equivalent number of load cycles. The simulation of the excess pore pressure build-up due to certain cyclic loading is based on undrained conditions, i.e. the excess pore pressure build-up due to cyclic loading is derived by disregarding the simultaneous consolidation process. The respected transfer method, in the form of contour plots, enables the consideration of site-specific cyclic direct ...
Modelling of excess pore pressure accumulation in sand around cyclically loaded foundations
In particular during storm events an accumulation of excess pore pressures may occur in the soil around cyclically loaded offshore foundations. The excess pore pressure build-up reduces the effective stresses in the soil and, hence, may negatively affect the structural integrity by influencing the soil-structure interaction. Besides a loss in bearing capacity, large plastic deformations may occur to the structure. Especially for offshore wind turbines an accurate estimation of such deformations is of great importance. Even though the consideration of this degradation effect on the bearing capacity is commonly demanded by the involved certification or approval bodies, no general applicable and accepted method for the calculative verification currently exists. Over the past decades several researchers investigated the excess pore pressure build-up around offshore foundations due to environmental cyclic loads. They tried to capture the loss of bearing capacity, the accumulation of plastic rotation and the essential influence on the serviceability limit state and fatigue design. However, even if there are some sophisticated concepts, none of them is seen as the simple general applicable choice. Within this thesis a new numerical method – termed Excess Pore Pressure Estimation method (EPPE) – is presented in great detail. This method allows for the transfer of the soil behaviour obtained in cyclic simple shear tests to the bearing behaviour of the entire foundation. Herein, the numerical model accounts for the cyclic excess pore pressure accumulation by respecting the element-based mean stress and stress amplitude as well as an equivalent number of load cycles. The simulation of the excess pore pressure build-up due to certain cyclic loading is based on undrained conditions, i.e. the excess pore pressure build-up due to cyclic loading is derived by disregarding the simultaneous consolidation process. The respected transfer method, in the form of contour plots, enables the consideration of site-specific cyclic direct ...
Modelling of excess pore pressure accumulation in sand around cyclically loaded foundations
Saathoff, Jann-Eike Sören (Autor:in)
01.01.2023
Hochschulschrift
Elektronische Ressource
Englisch
Porenwasserüberdruckakkumulation , finite element simulation , monopile , Finite-Elemente-Simulation , design , Einfachscherversuche , offshore , contour plot , Zyklische Elementversuche , partially drained conditions , ddc:550 , cyclic element tests , excess pore pressure accumulation , ddc:624 , Konturplot
Modelling of excess pore pressure accumulation in sand around cyclically loaded foundations
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