2D and 3D Numerical Modelling of Sheet Pile Walls in Soft Clay - Comparison of NGI-ADP and Creep-SCLAY1S

Abstract

This thesis examines the behavior of sheet pile walls in soft clay in 2D and 3D finite element analyses using PLAXIS, with a focus on comparing the constitutive models NGI-ADPandCreep-SCLAY1S.ThestudyisbasedonthegroundconstructionofHotel Draken at Järntorget in Gothenburg, where sheet pile walls of type PU12 and AZ18 were used to retain the soil during a staged excavation. The northern outer sheet pile wall was selected as the primary element of analysis, since inclinometer measurements were available for this wall. Both 2D and 3D models were created to simulate the construction sequence, including installation of sheet pile walls, staged excavation, casting of concrete, and installation of waling beams and corner struts. To address the impact of surcharge loading from ma chines or other equipment, two load scenarios were investigated. A sensitivity analysis was also performed for the sheet pile walls on the anisotropic plate input parameters in 3D. The results from the analyses show that the 2D plane-strain assumption overestimates the horizontal displacement compared to 3D. However, the choice of constitutive model also proved equally, or even more influential than the choice of dimensionality even for a non-symmetrical complex geometry. The more advanced Creep-SCLAY1S model produced results closer to the measured inclinometer data compared to the NGI-ADP model. The inclusion of surcharge loads from construction machinery was found to significantly affect the predicted displacement profile both in 2D and 3D, particularly in the upper portion of the wall. The sensitivity analysis of the anisotropic plate param eters regarding the area moment of inertia I2 and I12 in the 3D model showed to have negligible influence on computed wall displacements.