Design Of Coal Mine Entry Intersections

This paper describes a method to improve coal mine entry intersection design. The method considers the effect of in situ stresses, local geologic conditions, rock physical properties, and mining sequence. Development of the method is discussed, including the results of field instrumentation studies and numerical modeling investigations. Data required to evaluate the effects of roof span, mining sequence, entry orientation, and bolting patterns on intersection stability are also presented. Ground control studies conducted by the U.S. Bureau of Mines in two underground mines in the Illinois Coal Basin have shown that in situ horizontal stresses and roof geology have a critical effect on intersection stability. Methods to reduce the adverse effects of these parameters are emphasized. Typical failure behavior associated with specific geologic and horizontal stress conditions is' presented to illustrate proposed control methods to alleviate adverse ground conditions.