风沙区超大工作面开采土地损伤的演变与自修复特征

Evolution and self-healing characteristic of land ecological environment due to super-large coalface mining in windy and sandy region

为揭示超大工作面开采过程中土地损伤的演变规律,以神东矿区的部分典型工作面为研究对象,建立了土地生态环境观测方法,发现地表移动变形、地裂缝以及土壤物理性质等关键要素具有一定的修复能力:1与传统开采方式对比,超大工作面快速开采条件下,地表的移动变形和下沉总量没有变化,地表的下沉速度明显增大,地表受采动影响的时间缩短50%左右,相对均匀沉陷区的面积一次性达到78%,有效地促进了采后地形向采前状态的自修复;2地裂缝存在明显的"分区"特性,动态地裂缝扩展程度较弱并快速闭合,发育周期与采矿地质条件有函数关系;边缘地裂缝以"O"型圈分布于开采边界,裂缝角呈近似垂直角,分布范围明显减小,也表现出较强的自修复能力;3土壤物理性质的变化与地表移动变形以及地裂缝的分区特征基本吻合,均匀沉陷区的土壤物理性质在采动1 a后趋于采前水平,而非均匀沉陷区由于边缘地裂缝的存在,暂无自然修复现象,需要辅助人工治理。

In order to find out the evolution laws of land ecological environment due to Super-large Coalface Mining( SCM),a monitoring system of land ecological environment had been established at some typical workface in Shendong Coal Mine,the self-healing or natural healing abilities of land surface deformation,cracks and soil quality in the area had been investigated. The result shows that: 1 for an equivalent mining unit,the total amount of the surface movement and transformation of SCM was similar to traditional mining methods. However,the influenced time by mining was reduced around 50%,and the relative uniform subsidence region achieved 78% of the total subsidence area at once,its topography recovery as pre-mining showed a distinct ability of self-healing; 2 the ground cracks had obvious subarea feature with strong self-healing capacities. The dynamic cracks developed at uniform subsidence area without obvious heads in mining direction,which would close soon during the mining process. Its development cycle function was established with mining and geology. Marginal fissures occurred at mining boundary with ‘O'shape,the angle ofcrack was nearly vertical. The width of crack trip was smaller than that in traditional mining,with the value range from40- 50 m; 3 the changes of soil physical properties were consistent with the characteristic of surface deformation and ground cracks development. Within one year subsidence,the soil physical properties of uniform subsidence area tended to reach pre-mining levels,and most coal mining influence disappeared. By contrast,the heterogeneous subsidence needed manual control due to marginal cracks. The research results could provide a new principle for the ecology restoration at the coal mining subsidence area in the region.