What is the required thickness from the true river bed to the roof of a mine working under fractured igneous rock?

The required thickness from the true river bed to the roof of a mine working under fractured igneous rock is 50 meters. This guideline is established to ensure the structural integrity and safety of the mine workings. Fractured igneous rock can be variable in terms of stability, and having a sufficient thickness of rock between the riverbed and the mine workings is essential to prevent potential water inflow, which can lead to flooding or instability in the mine.

A minimum thickness of 50 meters acts as a buffer that reduces the risk of hydraulic pressure issues and allows for better management of water ingress, which is crucial for maintaining a safe working environment. Inadequate thickness could compromise the mine’s safety by increasing the likelihood of water-related accidents and geological instability, making this standard important for both safety and operational efficiency.