Research on Actual Measurement of Surface Subsidence Law for Fully-Mechanized Top Coal Caving in Extra Thick Seam

In order to study law of surface subsidence under situation of shallow buried depth,medium thick bedrock and extra thick seam using fully- mechanized top coal caving method,an observation station was established on surface above No. 914 Working Face of Dongpo Coal Mine. By analyzing the measured data,a set of complete prediction parameters for surface subsidenceand angular parameters were obtained. Under this geology and mining condition,the authors studied its mobile angle parameters and the dynamic deformation characteristics. The results showed that the subsidence factor was 0. 74,the displacement factor was 0. 25,the major influence tangent angle was2. 95,and the main influence spread angle was 86. 5°. It is concluded that under this situation,the initial period is short; the active period of surface subsidence velocity is large and moves violently,and subsidence in the active period occupies a high ratio of the total movement period. Under situation of shallow buried depth and medium thick bedrock,law of surface subsidence for extra thick seam using fully mechanized top coal caving method has its particularity.