If rock occasionally falls from the walls during excavation, how should it be classified?

The classification of the rock in this scenario as unstable rock is appropriate due to the observed behavior of the material. Unstable rock is characterized by its propensity to fall or slide, particularly when disturbed or under certain conditions, such as during excavation activities. The fact that rock occasionally falls from the walls indicates that it cannot be considered safely supported or reliable in terms of its stability.

In excavation work, understanding the stability of different types of rock is critical for ensuring safety. Unstable rock poses significant risks, since it can lead to hazardous conditions such as rock falls, which may injure workers or cause damage to equipment. Recognizing the signs of instability is essential for implementing appropriate safety measures, such as shoring or sloping, to mitigate risks and protect workers.

The other classifications, such as stable rock or loose rock, describe different conditions. Stable rock would be secure and reliable, with no risk of falling, while loose rock refers to material that may not be firmly attached and could be at risk of falling or sliding, but not necessarily from inherent instability. Raw rock typically refers to rock that has not been processed or altered but does not inherently indicate stability or instability. Thus, labeling the rock as unstable accurately reflects the safety concern and necessary precautions that should be