Hybrid Injections – Laboratory Testing and Field Experience During Tunnel Excavation-Video

Video Transcription

Video Summary

Aaron Katterbach explains hybrid grouting, which combines cement grout and polyurethane during a single injection process to address water ingress in challenging ground. Cement treats smaller fissures, while polyurethane helps seal larger, water-bearing fractures; adjusting the polyurethane dosage allows the grout to respond to conditions during injection. The method uses combined equipment and real-time monitoring, with injection records guiding when to add or reduce polyurethane. In a Swiss hydropower tunnel, hybrid grouting reduced water inflow from 135 to 5 liters per second or less. Its benefits include flexible grout design, reduced waste, and simultaneous sealing and consolidation.

Keywords

hybrid grouting

cement grout

polyurethane injection

water ingress control

hydropower tunnel