Assessment of shallow foundation performance on refilled urban soils: A review-based engineering perspective

Urban infrastructure development increasingly relies on reclaimed and refilled soils to meet growing spatial demands, yet the geotechnical performance of shallow foundations on such soils remains a persistent engineering concern. Refilled urban soils are often heterogeneous, poorly compacted, and variable in composition, leading to uncertainties in bearing capacity, settlement behavior, and long-term serviceability. This review-based research critically examines the performance of shallow foundations constructed on refilled urban soils from an engineering perspective, synthesizing findings from experimental studies, field investigations, and analytical models. Emphasis is placed on understanding soil-foundation interaction mechanisms, compaction quality, stress distribution, and time-dependent settlement characteristics. The influence of fill material properties, placement methods, moisture conditions, and post-construction loading on foundation response is discussed in detail. Additionally, the review highlights the role of ground improvement techniques, including mechanical compaction, soil stabilization, and reinforcement, in enhancing foundation performance. Comparative evaluation of conventional design assumptions against observed field behaviour reveals notable discrepancies, particularly in urban redevelopment projects. The research further explores the implications of inadequate site investigation and simplified design approaches on structural safety and maintenance costs. By integrating insights from existing literature, this paper aims to identify critical knowledge gaps and recurring failure patterns associated with shallow foundations on refilled soils. The review underscores the necessity for context-specific design methodologies, improved characterization of fill materials, and performance-based evaluation frameworks. Ultimately, this work provides a consolidated reference for researchers and practicing engineers, supporting more reliable foundation design and risk-informed decision-making in complex urban ground conditions. The findings contribute to advancing sustainable and resilient urban infrastructure development practices.