Influence of Mining Exploitation on Propagtion of Fault Crevices in the Earth's Crust.

Large scale mining exploitation, such as coal mining in the Polish Upper Silesian basin where it is estimated that over a period of centuries about 5 billion tons of coal and 6 million cu yd of rock have been removed from under ground changes the original distribution of stresses in the earth's crust, and can contribute to a propagation of cervices in the surrounding rock strata. Paper presents a simple model illustrating the propagation of a crevice in a homogeneous, isotropic, linearly-elastic medium under conditions corresponding to mining exploitation. That model determines the critical size of an excavation beyond which a propagation of a cervice, located underneath or above the level of an excavation would occur. A hypothesis correcting rock bursts with propagation of crevices is also presented.