ABSTRACT
The iterative technique necessitates the modification of material properties for elements where allowable stress levels have been exceeded. The iteration process is repeated until every element reaches a stability. In order to account for rock mass behavior, the strength of rock and coal was estimated using the Hoek-Brown failure criterion. In the determination of rock mass constants to be used for coal, a distinction was made between the structural quality of coal encountered at pillar ribsides, corners, and interior pillar regions. Underground mine models mostly show compressive and shear stresses. Safety factors of about 0.85 were calculated for these elements in the initial solution. During the first five iterations, moduli of elasticity were reduced using safety factors without an exponent. An effective iterative technique for the simulation of progressive failure in a longwall mine was developed. The combination of three-dimensional finite-element modeling and the presented technique of progressive failure simulation is an effective tool for the simulation of mining operations.
