AB - ABSTRACT: The consolidation of soft soils is a critical consideration for infrastructure stability, particularly in coastal regions where soft ground typically comprises multiple layers with varying properties. Creep plays a significant role in consolidation and is essential for accurately predicting long-term settlement in viscous soils. Accurate settlement prediction is influenced by loading patterns, soil stratification, and drainage boundary conditions. Despite advancements in theoretical approaches, comprehensive analytical solutions that integrate the effects of multilayered soil profiles and general drainage boundaries remain limited. This study presents a general spectral-based method for analysing the consolidation behaviour of multilayered soils under various loading patterns and drainage boundary conditions, including scenarios with or without prefabricated vertical drains (PVDs), impeded drainage, and time-dependent drainage conditions. The spectral-based solutions employ matrix operations to express the excess pore water pressure (EPWP) as unified solutions across multiple soil layers, effectively capturing the effects of complex boundary conditions. Based on this framework, a simplified Hypothesis B method is proposed to calculate long-term consolidation settlement. The proposed methods are validated against previous analytical solutions for special cases and field data, demonstrating their accuracy and flexibility in predicting EPWP dissipation and settlement. The study provides a more realistic representation of consolidation behaviour by incorporating general drainage conditions expressed as Robin Boundary Conditions (RBCs). The findings offer practical insights for optimizing engineering designs and improving settlement prediction in layered viscous soil foundations, offering a versatile and robust tool for geotechnical engineers to address the complexities of multilayered soil systems under diverse loading and drainage conditions. AU - Xu, B AU - Indraratna, B AU - Rujikiatkamjorn, C AU - walker, R DA - 2026/06/14 DO - 10.53243/ICSMGE2026-675 JO - 21st International Conference on Soil Mechanics and Geotechnical Engineering (Vienna) PY - 2026/06/14 TI - A NOVEL MULTILAYERED SOIL CONSOLIDATION SOLUTION BASED ON THE SPECTRAL METHOD TO PREDICT LONG-TERM SETTLEMENT Y1 - 2026/06/14 Y2 - 2026/07/01 ER -