Characteristics of height of water flowing fractured zone caused during ful-ly-mechanized caving mining in Huanglong coalfield

In order to study the law of height of water flowing fractured zone caused by fully-mechanized caving mining in Huanglong coalfield, this paper has systematically collected the measured data in the region, and methods of mathematical statistics and regression analysis were used to study the relationship among the height of water flowing fractured zone, width of working face, depth of coal seam and height of coal mining. The results show that:When the width of working face was less than 240 m and the height of coal mining was 8.5 to 9.5 m, the height of water flowing fractured zone under the soft stratum was always greater than that under the medium-hard stratum. When the width of working face was greater than 90 m and the height of coal mining was more than 14.5 m, the height of water flowing fractured zone under the soft stratum was always smaller than that under the medium-hard stratum. The height of water flowing fractured zone under the soft stratum and its ratio were both a single-peak curve with a maximum value as the height of coal mining increases. The height of water flowing fractured zone was a cubic function of the height of coal mining, and the ratio was a quadratic function of the height of coal mining. The maximum height was 239.97 m while the height of coal mining was 10.41 m, and the maximum ratio was 30.63 while the height of coal mining was 3.56 m. The height of water flowing fractured zone under the medium-hard stratum was affected by both the width of working face and the height of coal mining. When the width of working face was constant, the ratio of fractured zone height and mining height decreased gradually with the increase of mining height, and the change became more and more smaller, tended approximately to range from 11.00 to 14.30. When the height of coal mining was constant, the ratio increased with the width of working face. The height of the water flowing fracture zone increased with the width of the working face and the height of the coal mining.