Evaluation of the time-dependency of the mechanical parameters of conditioned cohesionless soils.

• Foams differently generated lead to different stability of conditioned soil. • Higher liquid generator flow rate in the production of foam leads to more stable foam. • Higher flow rates in the production of foam leads to less stable conditioned soil. • Soils conditioned through foams with lower FER have more stability over time. In tunneling technology, Earth Pressure Balance-Tunnel Boring Machine (EPB-TBM) technology operations require altering excavated soil rheology through soil conditioning, a vital aspect for optimal counterpressure control and soil extraction. This transformation is achieved by introducing additives like foam, and inherits its time-dependent behavior. Having observed a discrepancy in the stability of two foams generated with different flow rates, the core objective of research is exploring the influence of this parameter on time-dependency of mechanical properties of conditioned soil. This aspect is then studied also through a semi-quantitative analysis aimed to investigate correlations between the generation flow rates, the Foam Expansion Ratio, and used Foam Injection Ratio with the time-stability of conditioned soil properties. [ABSTRACT FROM AUTHOR]