Analysis of suction installation of monobucket in cohesionless soil.
Author
Geraldo De-Lima, Eric
Term
4. term
Education
Publication year
2021
Submitted on
2021-10-20
Pages
89
Abstract
As offshore wind turbines grow larger and move into harsher sites, foundation concepts must meet tighter technical and economic constraints. This thesis examines the suction installation of a suction bucket foundation (monobucket) with thickened skirt tips in dense cohesionless soil (sand) to assess how deviations from standard designs affect installation and where design parameters can be optimized. The study combines laboratory cone penetration tests (CPTs) and monobucket installation tests in Aalborg University’s geotechnical laboratory with a numerical model to analyze pore‑water seepage during suction. Results are compared with prior tests using uniform skirt thickness and with existing prediction methods. The experiments indicate that buckets with thickened skirt tips do not require higher suction to reach target depth, and that suction installation yields a substantial reduction (91.3%) in the maximum force needed to achieve the target depth. Overall, the findings are used to evaluate the suitability of common bearing‑capacity and CPT‑based prediction approaches for the investigated foundation configuration.
Udviklingen af større havvindmøller i mere krævende miljøer stiller nye krav til fundamentsløsninger. Denne afhandling undersøger sugeinstallation af et suge‑spandfundament (monobucket) med fortykket skørtkant i tæt kohæsionsfri jord (sand) for at vurdere, hvordan afvigelser fra standarddesign påvirker installationsprocessen, og hvor designparametre kan optimeres. Undersøgelsen kombinerer laboratorieforsøg med konuspenetrationsforsøg (CPT) og installationstests i Aalborg Universitets geotekniske laboratorium med en numerisk model til at analysere porevandsstrømning (seepage) under sugeinstallation. Resultaterne sammenlignes med tidligere tests, hvor skørtet havde ensartet tykkelse, samt med eksisterende forudsigelsesmetoder. Forsøgene viser, at monobuckets med fortykket skørtkant ikke kræver større sug for at nå måldybden, og at sugeinstallation medfører en markant reduktion (91,3 %) i den maksimale kraft, der kræves for at nå måldybden. Samlet set anvendes resultaterne til at vurdere, i hvilket omfang gængse beregnings- og CPT‑baserede metoder er egnede til at beskrive installationen af den undersøgte fundamentskonfiguration.
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