Research On The Safety Of Mining Under River At Selian Colliery

Many coal mining in China are threatened by water, prevention of water is a major problem in coal production and research. Shanxi, Shaanxi and western Inner Mongolia is an important large coal base in China. Coal resources in this area have thick coal bed, shallow buried depth and superior geological and mining conditions, but also present a new challenge to the mining of thick coal bed and shallow buried depth and the prevention of surface water.Selian coal mine is located in north-central part of Dongsheng coalfield, the western Ordos’ s region of Inner Mongolia. The mine pit has mined a number of shallow coal seams, of which the thickness of coal seam is changeable, and the surfaces are full of rivers and ravines. In this paper, the mining of shallow buried multiple coal seams beneath the riverbed in Selian coal mine is the main study object, which mainly achieved the following results:(1) Combined with mine geology and mining conditions, with the help of double side sealing sliding sideways device and rock hole detecting instrument, observing the height of water flowing fractured zone of 2-2 upper coal overlying strata in the full mining condition, finally conclusion that the maximum height of the water flowing fractured zone of the 2-2 upper coal in Selian coal mine is 82 m, split-production ratio was 20.5 and the development degree of mining-induced fractures was high.(2) Modeled after main coal seams the 2-2 upper coal and 2-2 middle coal, mining similar simulation experiment and numerical modeling calculation have been conducted to study overlying strata’s characteristics of deformation and failure under repeated mining. Among them, the similar simulation results showed that: after 2-2 upper coal’s excavation, the maximum height of fissure zone was 78 m, split-production ratio was 19.5; after 2-2 middle coal’s excavation, the height of water flowing fractured zone grown for the second time, of which the final height was 95m; the numerical modeling calculation results show that: after 2-2 upper coal’s excavation, fissure zone on the both sides of goaf had the highest growth, about 88 m, and mining split ratio was 22; after 2-2 upper coal’s excavation, mining-induced fissure of overlying strata was obviously in the shape of “saddle”, and after the secondary mining, the height of water flowing fractured zone highly developed to about 108 m.(3) According to mine geology and mining conditions, the continuity of the water flowing fractured zone and the surface river bed has been quantifiably analyzed by the use of matlab software and the safety of the various coal mining has been evaluated.For potential danger regions of surface rivers in Selian coal mine, two coal mining safety technical measures have been presented, limiting the mining thickness and non consolidated paste fill, and taking 2-2 upper coal as an example, the results of the height of non-cemented paste filling and limiting the mining thickness have been got.Results of this study, not only have practical significance to safely mining of multiple coal beds and shallow buried depth in Selian coal mine, but also can be used for the reference to further exploit the pressed coal under water.