Based on the engineering background of Shirengou iron mine

the evolution law of stress and strain of wall rock during formation process of goaf group in a typical ore blocks using similar material physical models and numerical simulation was researched. Firstly systematic analysis was made on evolution law of roof’s stresses and displacements and pillar’s stresses through the similarity material test. Secondly the disturbance range of wall-rock in the formation process of goaf group was systematically studyed using numerical simulation software. The results indicate that the evolution law of stresses and strains are great difference among goaf group and single exploitation. During the formation process

the stresses and strains of wall-rock are in dynamic development especially in the middle region of goaf group where the state of stresses and strains are worst. The disturbance to the wall-rock caused by mining in group region increases rapidly and the final disturbance range is not simple addition of which caused by mining single goaf. It is indicated that there is some “group effect” in the region that enhances the hazard grade of goaf.