Reuse of EPB-tunnelling excavated soil: An approach of logistic constraints estimation through modified Proctor test

• Published in: Tunnelling and underground space technology 2025-03, Vol.157, Article 106263
• Main Authors: Carigi, Andrea, Todaro, Carmine
• Format: Article
• Language: English
• Subjects: EPB; Laboratory test; Proctor; Reuse; Soil conditioning; Tunnelling
• ISSN: 0886-7798
• DOI: 10.1016/j.tust.2024.106263

The exponential growth of tunnelling projects worldwide necessitates efficient management of excavated soil, particularly from Earth Pressure Balance Tunnel Boring Machines (EPB-TBMs). This study investigates the temporal evolution of mechanical properties in EPB-excavated soil, focusing on the conditioning process’s impact. Through a comprehensive literature review, gaps in understanding the soil’s transition from a liquid-like state back to its solid form are identified. Existing studies touch on mechanical property changes over time but lack detailed temporal analyses. Our research addresses this gap by examining the recovery of soil compactability over time, crucial for its reuse. By conducting modified Proctor tests at different time intervals post-conditioning, we elucidate the relationship between soil properties and conditioning parameters. Our findings reveal a direct correlation between recovery time and total water content, influenced by added water and foam injection ratio. We demonstrate that different conditioning parameter combinations yield similar immediate properties but divergent recovery times, which are crucial for logistical planning and environmental suitability. This study offers valuable insights into optimizing EPB-TBM excavation logistics, enhancing soil reuse efficiency, and advancing sustainability in civil engineering projects.