Numerical simulations on ice-structure interaction in shallow water
Moving sea ice causes high loads on Arctic offshore structures when it breaks against them. Many of these structures are built in relatively shallow water, which affects the loading process. The ice breaking process in shallow water involves complex interactions between the intact ice sheet, the ice...
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ftaaltouniv:oai:aaltodoc.aalto.fi:123456789/18624 2023-05-15T15:03:43+02:00 Numerical simulations on ice-structure interaction in shallow water Jää-rakenne-vuorovaikutuksen numeerinen mallinnus matalassa vedessä Häsä, Riikka Polojärvi, Arttu Insinööritieteiden korkeakoulu Aalto-yliopisto Aalto University 2015-10-19 application/pdf https://aaltodoc.aalto.fi/handle/123456789/18624 en eng https://aaltodoc.aalto.fi/handle/123456789/18624 URN:NBN:fi:aalto-201511205181 openAccess ice mechanics ice-structure interaction grounding arctic offshore structures numerical modelling combined finite-discrete element method G2 Pro gradu, diplomityö Master's thesis Diplomityö masterThesis 2015 ftaaltouniv 2022-12-15T19:14:48Z Moving sea ice causes high loads on Arctic offshore structures when it breaks against them. Many of these structures are built in relatively shallow water, which affects the loading process. The ice breaking process in shallow water involves complex interactions between the intact ice sheet, the ice blocks formed in the process, the structure and the seabed. In this thesis, ice-structure interaction on a wide sloping structure in shallow water is studied using a 2D combined finite-discrete element method (FEM-DEM). The intact ice is modelled as a nonlinear Timoshenko beam and its fracture into smaller pieces is modelled using the cohesive crack model. The discrete element method is used for contact force calculation between the ice blocks, the structure and the seabed. In the work reported here, the inclination angle of the structure, the ice thickness and the water depth are varied to study how these parameters affect the ice rubble grounding and the ice loading process. The simulation results suggest that grounded rubble leads to higher loads on the structure than non-grounded rubble. The loads on the structure increase with thicker ice and decreasing water depth. In addition, a larger inclination angle induces higher loads on the structure throughout the simulation. The load events on the structure are related to simultaneous ride-up events of the rubble and the loads are transmitted to the structure along so-called force chains. Furthermore, the probability of overtopping increases in shallow water. The load increase and the increased probability of overtopping in shallow water are caused by the supporting effect of the seabed. Sudden load drops on the structure are related to buckling of the force chains. When the rubble is grounded, the force chains are supported from below by the seabed and form above by the rubble above. Thus they sustain more loads than force chains in non-grounded rubble. Liikkuva jää aiheuttaa suuria kuormia arktisille merirakenteille jään murtuessa rakennetta vasten. Monet näistä ... Master Thesis Arctic Arktis* Ice Sheet Sea ice Aalto University Publication Archive (Aaltodoc) Arctic |
institution |
Open Polar |
collection |
Aalto University Publication Archive (Aaltodoc) |
op_collection_id |
ftaaltouniv |
language |
English |
topic |
ice mechanics ice-structure interaction grounding arctic offshore structures numerical modelling combined finite-discrete element method |
spellingShingle |
ice mechanics ice-structure interaction grounding arctic offshore structures numerical modelling combined finite-discrete element method Häsä, Riikka Numerical simulations on ice-structure interaction in shallow water |
topic_facet |
ice mechanics ice-structure interaction grounding arctic offshore structures numerical modelling combined finite-discrete element method |
description |
Moving sea ice causes high loads on Arctic offshore structures when it breaks against them. Many of these structures are built in relatively shallow water, which affects the loading process. The ice breaking process in shallow water involves complex interactions between the intact ice sheet, the ice blocks formed in the process, the structure and the seabed. In this thesis, ice-structure interaction on a wide sloping structure in shallow water is studied using a 2D combined finite-discrete element method (FEM-DEM). The intact ice is modelled as a nonlinear Timoshenko beam and its fracture into smaller pieces is modelled using the cohesive crack model. The discrete element method is used for contact force calculation between the ice blocks, the structure and the seabed. In the work reported here, the inclination angle of the structure, the ice thickness and the water depth are varied to study how these parameters affect the ice rubble grounding and the ice loading process. The simulation results suggest that grounded rubble leads to higher loads on the structure than non-grounded rubble. The loads on the structure increase with thicker ice and decreasing water depth. In addition, a larger inclination angle induces higher loads on the structure throughout the simulation. The load events on the structure are related to simultaneous ride-up events of the rubble and the loads are transmitted to the structure along so-called force chains. Furthermore, the probability of overtopping increases in shallow water. The load increase and the increased probability of overtopping in shallow water are caused by the supporting effect of the seabed. Sudden load drops on the structure are related to buckling of the force chains. When the rubble is grounded, the force chains are supported from below by the seabed and form above by the rubble above. Thus they sustain more loads than force chains in non-grounded rubble. Liikkuva jää aiheuttaa suuria kuormia arktisille merirakenteille jään murtuessa rakennetta vasten. Monet näistä ... |
author2 |
Polojärvi, Arttu Insinööritieteiden korkeakoulu Aalto-yliopisto Aalto University |
format |
Master Thesis |
author |
Häsä, Riikka |
author_facet |
Häsä, Riikka |
author_sort |
Häsä, Riikka |
title |
Numerical simulations on ice-structure interaction in shallow water |
title_short |
Numerical simulations on ice-structure interaction in shallow water |
title_full |
Numerical simulations on ice-structure interaction in shallow water |
title_fullStr |
Numerical simulations on ice-structure interaction in shallow water |
title_full_unstemmed |
Numerical simulations on ice-structure interaction in shallow water |
title_sort |
numerical simulations on ice-structure interaction in shallow water |
publishDate |
2015 |
url |
https://aaltodoc.aalto.fi/handle/123456789/18624 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Arktis* Ice Sheet Sea ice |
genre_facet |
Arctic Arktis* Ice Sheet Sea ice |
op_relation |
https://aaltodoc.aalto.fi/handle/123456789/18624 URN:NBN:fi:aalto-201511205181 |
op_rights |
openAccess |
_version_ |
1766335568899211264 |