Abstract:

With the increasing of mining depth, thick overburden becomes the main feature of deep underground mines. By geophysical surveys, deformation monitoring, as well as the theoretical analysis, mechanism of surface subsidence caused by underground mining in a typical thick overburden metal mine was analyzed. The results obtained show that goaf in thick overburden provides space for ground subsidence; and smaller thickness of the gob creates condition for the development of ground subsidence, which is the main reason for surface subsidence. After surface subsidence occurred, centering on collapse pit, the range of subsidence continues to expand outward. Because of the strike of goaf and geological defects, such as faults and rock interfaces, collapse pit expands faster in the north, west and south than in the east. Rainfall will increase the expansion speed of the collapse pits, because the infiltration of surface water accelerated the movement and subsidence of the surrounding rock and soil toward the pit.

Key words: thick overburden, goaf in overburden, geophysical survey；surface deformation monitoring；underground mining；surface subsidence