Abstract: To achieve effective control of the deformation of surrounding rock and surface subsidence during the transition
from open-pit to underground mining of the Jiajiaoying Iron Mine,the FLAC3D numerical simulation method was adopted to construct
a mining structure model for the panel area of the open-pit followed by filling mining method. The inhibitory effect of the
filling body and panel barrier pillars on the deformation of the panel area surrounding rock under different filling support rates
during the mining process was studied. The stress distribution characteristics and deformation failure laws of the panel area surrounding
rock and panel barrier pillars under different influencing factors were obtained,as well as the influence of the filling
support rate of the mining area on the stress distribution characteristics and deformation failure laws of the surrounding rock and
inter-zone pillars. The study results show that:① The filling support rate has little effect on the maximum principal stress distribution
of the panel area surrounding rock,with the maximum principal stress being approximately 71. 0 MPa. After stress release,
it reaches about 4. 0 MPa. The maximum principal stress of the mining area surrounding rock is 73. 02 MPa to 73. 15
MPa,and after stress release,it is approximately 0. 6 MPa. The minimum principal stress in the horizontal direction of the min
ing area middle zone surrounding rock is not affected by the support rate,with a value of approximately 0. 78 MPa. The minimum
stress in the vertical direction is 1. 57 MPa to 1. 61 MPa,and it shows a decreasing trend with the increase of the support
rate. ② During the mining excavation process,large displacements occurred at the upper and lower panels and the top and bottom
plates of the mining area. However,as the filling support rate increased,the displacements all showed a decreasing trend.
After the pan area mining was completed successively and the filling and support were carried out,there were many shear and
tension plastic zones distributed on the top and bottom plates of the mining area. With the increase of the filling support rate,
the distribution range gradually decreased. The plastic zone of the top plate decreased significantly. ③ Under different filling
support rates,the maximum principal stress distribution range within the panel barrier pillars remained basically unchanged,
with the maximum principal stress being 126. 8 MPa to 141. 0 MPa. When the filling support rate increased from 80% to 90%,
the minimum principal stress of the panel barrier pillars decreased from 0. 74 MPa to 0. 73 MPa,showing a decreasing trend.
④ With the increase of the filling support rate,the tension and shear plastic failure zones of the panel barrier pillars continuously
decreased. When the filling support rate reached 90%,the stability of the panel barrier pillar was better. The study results
have certain practical significance for improving the stress state of the mining area and pan area surrounding rock and preventing
surface subsidence.