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...

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Bibliographic Details
Published in:Tunnelling and underground space technology 2024-08, Vol.150, p.105828, Article 105828
Main Authors: Bahrami, Nima, Carigi, Andrea, Todaro, Carmine
Format: Article
Language:English
Subjects:
EPB-TBM
Flow rate
Foam
Soil conditioning
Time-dependency
Tunneling
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Summary:•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.
ISSN:0886-7798
1878-4364
DOI:10.1016/j.tust.2024.105828