Study on Features of Surface Dynamic Movement and Deformation Caused by Coal Mining Under Thick Alluvium

In order to protect of buildings and control the ground subsidence in the area of covering thick alluvium, based on the measured data of surface moveme nt and deformation above No. 11011 working face of Zhaogu No. 1 Coal Mine, dynamic changes of surface subsidence curve, surface subsidence maximum velocity, su rface movement and deformation duration and lagging distance of maximum subsidence velocity were analyzed with mining under thick alluvium. The results indicated t hat rapid changes in value of surface subsidence appeared, maximum of subsidence velocity was 24. 5 mm /d, movement was intense and range of surface subsidence increased obviously. The surface subsidence coefficient expected was more than one in case of full extraction. In the surface movement duration, active phase account ed for53. 4% the total time, while 91. 3% the total subsidence occurred in this period, and decline phase of surface subsidence lasted for a long time, but had a ltter su bsidence. The working surface of maximum subsidence velocity lag distance was 182 m. The above resluts showed that with the coal mining under thick alluvium, the s urface had a several features, for example, subsidence was sensitive to coal caving effect, surface subsidence velocity and coefficient was large, and surface movemen t was serious, and decline phase of surface subsidence lasted for a long time.