Effect of gradation characteristics on seepage failure in foam-conditioned gap-graded soils for EPB shield tunneling

Key Points

• Seepage failure often occurs in gap-graded soils during EPB shield tunneling, impacting tunnel stability.
• High seepage rates were observed under specific gradation characteristics and foam conditioning conditions.
• Analysis of foam-conditioned gap-graded soils highlights critical parameters affecting their performance.
• Understanding these gradation characteristics may lead to enhanced safer tunneling operations.