Numerical assessment on pile stability in liquefiable soil
Author
Mikkelsen, Aske Theis
Term
4. term
Education
Publication year
2018
Submitted on
2018-07-08
Pages
64
Abstract
Den voksende udbygning af offshore vind i seismisk aktive regioner skærper behovet for at forstå, hvordan jordskælv og likvefaktion påvirker monopæle. Dette speciale undersøger pælers laterale respons og stabilitet i likvefierbar, mættet jord under dynamisk jordskælvslast. Arbejdet bygger på 3D-finite element analyser i PLAXIS 3D med den avancerede konstitutive jordmodel UBC3D-PLM, hvor modelparametre kalibreres mod multistadie triaxialforsøg. Den numeriske opsætning omfatter geometri, randbetingelser, mesh og en pålagt seismisk belastning. Der udføres både en dynamisk vurdering af pælflytninger og udviklingen af det overskydende poretryksforhold omkring pælen samt en post-likvefaktionsanalyse, der knytter p-y-kurver til den residuale forskydningsstyrke og stivhed i den likvefierede jord. Resultatafsnittene i afhandlingen fokuserer på disse reaktioner, men specifikke kvantitative fund fremgår ikke af det udleverede uddrag. Samlet set præsenterer arbejdet en kalibreret, numerisk ramme til at vurdere pælerespons før, under og efter likvefaktion, med relevans for forprojektering af offshore fundamenter.
As offshore wind expands into seismically active regions, understanding how earthquakes and liquefaction affect monopile foundations becomes critical. This thesis examines the lateral response and stability of piles in liquefiable, saturated soils under dynamic earthquake loading. The study employs 3D finite element analyses in PLAXIS 3D using the advanced UBC3D-PLM constitutive soil model, with parameters calibrated against multistage triaxial tests. The numerical setup covers geometry, boundary conditions, meshing, and imposed seismic excitation. Both the evolution of the excess pore pressure ratio around the pile and pile displacements during shaking are evaluated, and a post-liquefaction analysis relates p-y curves to the residual shear strength and stiffness of the liquefied soil. The results sections of the thesis address these responses, but specific quantitative outcomes are not included in the provided excerpt. Overall, the work presents a calibrated numerical framework for assessing pile behavior before, during, and after liquefaction, supporting early-stage design of offshore foundations.
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