浅埋煤层沟谷径流下开采顶板突水预测分析

Prediction analysis of roof water-inrush in shallow coal seam with surface valley runoff

为了准确预测浅埋煤层沟谷径流下开采顶板突水灾害,基于多元素拟合公式及有限元差分软件FLAC3D应力-渗流耦合系统,进行了突水判别分析与仿真模拟预测。拟合公式计算表明,在该地质条件及地形条件下会发生顶板突水事故。FLAC3D数值模拟分析表明,当工作面在过沟谷前属于安全开采地带,当工作面推进至沟谷下方时,导水裂隙与沟谷贯通,会造成严重的顶板突水事故,但在随后的开采中,其隔水层的隔水性具有周期性"破坏-恢复"特点;当工作面完全通过沟谷,隔水土层的隔水性完全恢复,并结合隔水层的采动破坏-恢复规律提出了沟谷下留设煤柱的防突水开采措施。研究成果证明理论判别计算结合FLAC3D的应力-渗流耦合系统能够较真实地反映沟谷径流下的采动渗流耦合破坏过程,可进行定性和定量地突水预测。

In order to accurately predict the roof water-inrush disaster in shallow coal seam with sur- face valley runoff, based on the multi-element fitting formulas and the stress and fluid flow coupled sys- tem module of finite difference software FLAC^3D, this paper provides analyses of water-inrush identifi- cation and a simulation modelling prediction work. The fitting formulas show that, under the condition of such geology and topography, the roof water-inrush disaster could easily happen. The FLAC^3D nu- merical simulation analysis indicates that the mining is safe before the working face passing valley area; When it advances to the location below the valley, the connection of fissure zone and valley would lead to a serious roof water-inrush disaster, but the water-resisting property of aquifer shows a weekly ＂damage-recovery＂ period in the subsequent mining; When the entire working face pass the valley, the water-resisting property of aquifer is fully recovered. Hence, following the mining damage-recovery law of aquifer, the mitigation measure of water-inrush prevention by setting coal pillar under valley is pro- posed. The results prove that the theoretical identification using stress and fluid flow coupled system in FLAC^3D can truly reflect the development of cracking process of mining seepage, which could qualita- tive and quantitative predict the water-inrush.