PAM-S helps water-rich sand crossing: settlement held to 3 mm

A metro cross passage in East China recently completed its crossing section through water-rich fine silty sand. The permeable ground made plain bentonite slurry lose heavily and settlement hard to control.

The project switched to PAM-S polymer mud with a 1:250 concentrated section through the crossing. The film formed quickly on the wall, cutting slurry loss from above 15 L/min to under 2 L/min. With staged top-ups and settlement monitoring, peak settlement was 3 mm and hole acceptance 100%.

As the line’s controlling section, the stable performance helped the project break through 6 days ahead of schedule.