Abstract:The goaf may face a series of deformation and settlement problems when the room-pillar mining method is used to excavate ore and pillars in the deep strata. To this end, a deep room-pillar model with two levels was made, and the pillar recovery was carried out. The instantaneous deformation responses during the pillars recovery and the long-term settlements after the pillar recovery were analyzed. During the pillar recovery, different regions of surrounding rocks suffer from different dynamic disturbances which can be divided into three types, including (I) the combined action of blasting disturbance and unloading disturbance, (II) the sequential action of blasting disturbance and unloading disturbance, and (III) the action of unloading disturbance. After the pillar recovery, the settlement above the first recovering pillar is the largest, which has a traction effect on the settlement in other areas. The settlement process can be divided into two stages, stable displacement stage and unstable displacement stage. When the pillar-room system undergoes the unstable displacement stage, rock spalling and further cascading collapse will occur.

Key words: room-pillar system; physical model test; settlement; dynamic response; deformation