Abstract:Illegal mining has a great influence on stability of mines. In the paper,two-dimensional numerical simulation on Jinshandian underground iron mine is carried out by using finite element method and discrete element method. The regulations of surface deformation and surrounding rock movement with/without illegal mining are obtained,respectively. The obtained results indicate that an elliptic disturbed zone is formed around underground gob and the major axis of ellipse is parallel with the tendency of the orebody. Gobs formed by illegal mining and underground mining will not connect. In addition,illegal mining has little influence on the size of underground disturbed zone. Because of stress redistribution caused by illegal mining,the size of surface subsidence increases near surface gob;and horizontal displacement of surface increases greatly,but the range of surface subsidence is almost found without change.