Observation and Study on Surface Ground Subsidence Speed of Fully Mechanized Top Coal Caving Mining in Thick Seam

In order to have the surface ground subsidence speed and other parameters of the fully mechanized top coal caving mining in the thick seam,with the establishment of the surface ground movement observation station,the surface ground subsidence occurred by the fully mechanized top coal mining in the thick seam was observed and the surface ground subsidence features under the conditions of the fully mechanized top coal caving mining in thick seam were analyzed.From the observation and analysis,the surface ground subsidence coefficient obtained was 0.91.The starting distance was 50~60 m and would be 1/5~1/6 of the mining depth.The advance influence distance was 183 m.Based on the circumstance,the max subsidence speed and the max subsidence speed delay angle of the surface ground would be 51 mm/d and 76.3~78.3° individually.The above showed that under the fully mechanized top coal caving mining in thick seam,the surface ground in that area would have a serious movement,a quick subsidence speed,a small starting distance and other features.