关键词: 软弱围岩, 地下开采, 地面沉降

Abstract: The surrounding rock of an iron mine is extremely soft and broken，and the filling condi⁃ tion is not good after mining. After years of mining，the ground has different degrees of subsidence. Based on the statistics of land subsidence monitoring data in mining area，the variation law of land subsidence in subsidence area is studied. The results show that the mining area has experienced two stages of slow defor⁃ mation and surface subsidence basin，both vertical subsidence and horizontal expansion are accelerating. The maximum cumulative settlement in vertical direction is 1 078 mm，and the maximum settlement veloci⁃ ty is 1.56 mm/d. Horizontal displacement is mainly in the northeast direction，the maximum cumulative dis⁃ placement of 1 168.5 mm，the maximum expansion rate of 1.73 mm/d. Weak surrounding rock，large min⁃ ing disturbance，poor ore body occurrence conditions and poor filling process are the main factors leading to land subsidence. By establishing a mathematical statistical model to predict the cumulative settlement of the last month，the highest accuracy is 99.5%.

Key words: soft surrounding rock, underground mining, land subsidence