Analysis of surface mining subsidence laws under thick alluvial Quandian Mine

In order to study the laws of surface subsidence due to mining coal under thick alluvium of Quandian mine, two survey lines were designed on the surface above the first face. By analyzing the position of the maximum subsidence point of the tendency survey line, the zenith angle was obtained, and the correctness of taking bedrock thickness instead of average mining depth to design the position of the trend survey line in the mining area was confirmed; and based on the analyses of the measured data, the critical size of the gob full opening in the geological and mining conditions didn't follow the general law that the gob would reach the critical size when the panel has moved for a distance of 1.2H0 - 1.4H0. These results showed that the bedrock played a major role in the spread of whole overburden subsidence in the geological and mining conditions, while the loose layer had less affection. In addition, based on the analyses of the measured data, some rock movement parameters and probability integral prediction parameters of the surface subsidence of Quandian mine in the geological and mining conditions have been obtained. The study would have some important theoretical significance and practical guidance for implementing mining beneath buildings, water bodies and railways and prevent of this coal field as well as surface structure damage control.