How thick must a mine working be when driven under unfractured igneous rock?

In the context of mine ventilation and safety, the thickness of a mine working under unfractured igneous rock is determined by stability considerations and the inherent properties of the rock. Igneous rocks are generally characterized by their strength and structural integrity when they are unfractured.

A thickness of 25 meters serves as a standard minimum for ensuring adequate stability in this scenario. This thickness allows for sufficient rock cover to support the weight of the overlying material, reducing the likelihood of collapse due to the immense pressure exerted above. It also contributes to the safe operation of the mine, providing a buffer against potential geological hazards.

Thicker values not only may be unnecessary but could also add to construction and operational costs without significant benefits to safety in stable conditions. Thus, adhering to the guideline of 25 meters strikes a balance between safety, economic efficiency, and engineering best practices in mining operations beneath unfractured igneous formations.