30 CFR § 57.3360
Ground support use.
SCALING AND SUPPORT--UNDERGROUND ONLY
Ground support shall be used where ground conditions, or mining experience in
similar ground conditions in the mine, indicate that it is necessary. When
ground support is necessary, the support system shall be designed, installed,
and maintained to control the ground in places where persons work or travel
in performing their assigned tasks. Damaged, loosened, or dislodged timber
use for ground support which creates a hazard to persons shall be repaired or
replaced prior to any work or travel in the affected area.