The mechanism of rock movement caused by underground mining in Chengchao iron

摘要

Based on the geological conditions,underground mining situations,as well as the status of cracks and surface deformation of Chengchao Iron,a cantilever mechanical model is proposed.The bottom-up tubular collapse in the deep rock mass causes the horizontal tectonic stress release which favors the bending fracture deformation and destruction of the NWW-trending joints.This model can explain the formation of four zones in the deep rock mass:rupture zone,the transition zone of rupture to deformation,the deformation zone,and the undisturbed zone.In such a mode,it inevitably leads to different deformation areas on the surface related to the different zones in the deep rock mass.So the mine surface is divided into four related areas:cumulative deformation area,crack-producing area,crack-extending area,and crack-closing area.As mining progresses,four zones of the deep rock mass will gradually extend downward,while four areas of the surface deformation will gradually expand outward.