Rigid inclusions state-of-practice

Deep foundations, traditionally implemented through piles, have long been the conventional solution for supporting loads in low-strength or highly compressible soils. However, in recent decades, ground improvement has emerged as a sustainable technical alternative, offering significant reductions in both construction time and costs. These methods enhance the physical and mechanical properties of soils or improve overall ground performance through the introduction of inclusions with superior characteristics. Rigid inclusions are a prominent technique within this domain, reinforcing compressible soils using columnar elements composed of concrete or grout. Rigid inclusions have become widely adopted due to their capacity to provide reasonable control over both bearing capacity and settlement behaviour. This paper examines the evolution and application of rigid inclusions, detailing their behaviour, failure mechanisms, design methodologies, and modern analytical approaches. The discussion extends to construction techniques, referencing relevant case studies, and highlighting recent innovations in the construction and application of rigid inclusions. By synthesising these insights, the paper highlights the advancements and practical advantages of rigid inclusions in modern geotechnical engineering practices.