The Effect of Blasting On The Grout-Video

Video Transcription

Video Summary

The presentation examines whether blasting damages grout during Scandinavian drill-and-blast tunneling, where crews commonly wait five to seven hours for grout to harden. A field test measured grout properties and vibration-related shear strain, then blasted a borehole three hours after grouting and retested nearby holes. Three of four adjacent boreholes remained tight after blasting; one plug eroded during subsequent water-loss testing. The results suggest that brief blast vibrations may temporarily deform young grout without causing lasting loss of sealing, challenging the need for a fixed waiting period. The speaker proposes assessing grout using its shear modulus and comparing predicted blast-induced strain with the grout’s strength. However, the study is ongoing, and more testing is needed to characterize grout behavior and optimize excavation cycles. Improved grout-property testing and monitoring of hydraulic conditions could help reduce unnecessary delays and costs.

Keywords

drill-and-blast tunneling

grout hardening

blast vibration

shear strain

excavation cycle optimization