Cemented Paste Backfill Geomechanics at a Narrow-Vein Underhand Cut-and-Fill Mine.

Underhand cut-and-fill mining has allowed for the safe extraction of ore in many mines operating in weak rock or highly stressed, rockburst-prone ground conditions. However, the design of safe backfill undercuts is typically based on historical experience at mine operations and on the strength requirements derived from analytical beam equations. In situ measurements in backfill are not commonplace, largely due to challenges associated with instrumenting harsh mining environments.

Long-Term Stability of a 13.7 × 30.5-m (45 × 100-ft) Undercut Span Beneath Cemented Rockfill at the Turquoise Ridge Mine, Nevada.

In 2001, researchers from the National Institute for Occupational Safety and Health (NIOSH) installed instruments at the Turquoise Ridge Mine in cooperation with Placer Dome, Inc. to monitor the geomechanical behavior and stability of a cemented rockfill (CRF) sill and the surrounding host rock during test mining of a large undercut span beneath backfill. Six parallel, adjacent drifts were mined and backfilled to construct a CRF sill, approximately 22.