沙漠浅滩地表径流保水煤柱留设生态意义及方法

Ecological significance and method to design protective coal pillar on surface runoff in desert shoal area

生态脆弱矿区地表径流保护煤柱的留设直接影响流域生态环境演变。以陕北神南矿区为研究背景,通过野外地质调查、取样测试,查明了沙漠浅滩矿区流域生态承载特征,在导水裂隙带发育规律研究的基础上,剖析了传统保安煤柱留设的局限性,从地下水动力学角度,提出了基于采动分水岭的保水煤柱留设方法。结果表明：沙漠浅滩地表径流承载了干旱缺水矿区绝大多数生态、生活、生产用水,而沙漠浅滩地表径流91.33%的流量源自砂层潜水补给,研究区地表流域附近首采煤层导高预计发育为40.4-69.2 m,采动造成采空区上方砂层潜水位消失,而基于分水岭的煤柱留设方法避免了地表径流向采空区反向渗流。实践计算证明研究区内常家沟保水煤柱62 m,大于传统保安煤柱34.8 m。

It is significant for the mining watershed ecology to design protective coal pillar on surface runoff in ecologically fragile mining area. Taking Shennan mining area in Northern Shaanxi Province as research area, ecological carrying characteristics of watershed in desert shoal mining area have been investigated with methods of field geological investigations and sampling tests. Based on the research of development rules of water flowing fractured zone, limitations of traditional design for protective coal pillar have been analyzed. And a new method to design protective coal pillar, on the basis of watershed mining, has been proposed from the point of hydrodynamics of groundwater. The results have shown that on one hand surface runoff satisfies the most gross of ecological water requirement, as well as domestic and production water demand, but on the other hand 91.33% of surface runoff comes from ground water recharge in the sand layer. The water flowing fractured zone heights will reach 40.4 m to 69.2 m as first coal seam＇s mining around drainage basins, and at the same time, sandy aquifer above goaf will drain off after mining. The new designing method based on watershed can avoid reverseseepage of surface runoff into goaf. The practical calculation has shown that the designed protective coal pillar is 62 m around Changjiagou River based on watershed, which is greater than 34.8 m of the traditional design for protective coal pillar.