Abstract: To study the long-term stress and deformation states of strip pillar, the strip pillars in Daizhuang coal mine were monitored with borehole stress-meters and displacement monitors for a long time. The study results show that the strip pillar of 70 m in width can be divided into 58 m elastic zone,4～5 m plastic failure zone and 1 m fully broken zone. The actual support ability of each zone is determined based on the correction of measured data, for example, the actual long-term support ability of the strip pillar in depth of 5 m is around 11.896 MPa, while the average long-term support ability of the intermediate part of 50 m in width is 29.5 MPa, and the bearing capacity of pillar is greater than the weight of overlying strata within the mining and reservation width. Meanwhile, the goaf is filled by the falling gangue, which can certainly play a role in supporting the roof and overlying strata, so the strip pillar can keep stable for a long time.

Key words: strip pillar, stress, lateral deformation, long-term state, subarea, long-term support ability