Answer:
Inserting rock bolts.
Explanation:
A rock bolts is a long bolt that is used for bracing while carrying out rock excavation on dangerous rock cliffs, road cuts etc. It is done by spreading out the rock bolts through the drilled bolts in the rock, this will help to keep rock fractures together. In the 1890's was the first time rock bolt was used in mining operation as a from of safety in mining to avert the danger of collapse.
