厚土层下浅埋煤层开采覆岩倾向结构分区与下沉预计模型

Overburden inclined structure zones and subsidence prediction model in shallow buried thick soil layer coal seam mining

为探究厚土层下浅埋煤层开采的覆岩与地表下沉预计方法,以柠条塔煤矿1^(-2)煤层开采为背景,结合理论分析与物理模拟的方法,揭示了厚土层下浅埋薄基岩煤层采场覆岩倾向结构分区及其特征,建立了分区下沉力学模型,提出了覆岩与地表下沉预计方法。研究表明:厚土层薄基岩浅埋煤层长壁开采后,沿覆岩倾向方向的垮落和移动可以分为边界煤柱顶板F形岩柱区、采空区顶板梯形垮落区和区段煤柱顶板倒梯形岩柱区,采空区顶板梯形垮落区上部基岩与土层下沉量最大,边界煤柱顶板F形岩柱区的下沉量和区段煤柱顶板倒梯形岩柱区下沉量较小。基岩关键层对上覆岩层及表土层的下沉起控制作用,土层下沉取决于基岩与土层交界面处下沉盆地的形态;通过建立分区下沉力学模型,得到了覆岩与地表下沉量曲线方程。分析得出:采空区顶板梯形垮落区上部基岩下沉量主要与采高和垮落顶板碎胀系数有关,边界煤柱顶板F形岩柱区和区段煤柱顶板倒梯形岩柱区上部的基岩下沉量主要与采高及岩柱结构分布载荷有关。物理模拟实验与理论计算得到1^(-2)煤层开采地表最大下沉量分别为1.1 m和1.07 m,与实测最大下沉量基本相符,验证了下沉预计理论模型准确性,为厚土层下浅埋煤层采场覆岩与地表下沉预计提供了新方法。

In order to explore subsidence prediction method of overburden strata and earth surface during coal seam mining in shallow buried thick soil layer,with No.1^(-2) seam mining in Ningtiaota coal mine as background,the overburden inclined structure zones and characteristics were revealed through theoretical analysis and physical simulation,subsidence prediction models were established,and subsidence prediction method of overburden strata and earth surface was proposed.Results have shown that after mining of shallow buried thick soil layer thin bedrock coal seams,based on overburden caving and subsidence characteristics,overburden inclined structure can be divided into three zones:F-shape strata zone in boundary pillar,trapezoidal caving zone in goaf roof,and inverted trapezoidal rock pillar area in section pillar roof,with maximum amount of subsidence of bedrock and soil layer in trapezoidal caving zone in goaf roof and comparatively less subsidence in F-shape strata zone in boundary pillar and inverted trapezoidal rock pillar area in section pillar roof.The key stratum in the bedrock plays a controlling role in the subsidence of its overburden strata and soil layer;the subsidence of soil layer depends on the shape of interface subsidence basin between bedrock and soil layer.Through the established subsidence mechanical model,the subsidence curvilinear equations of overburden strata and earth layer were obtained.The analysis has shown that subsidence of upper bedrock in trapezoidal caving zone in goaf roof is mainly related to mining height and bulking coefficient of caving roof,while subsidence of upper bedrock in F-shape strata zone in boundary pillar and inverted trapezoidal rock pillar area in section pillar roof is mainly related to mining height and distribution load of rock pillar formations.Through physical simulation and site measurement,theoretical models were verified,maximum surface subsidence of No.1^(-2) seam mining obtained through experiment and theoretical calculation is 1.1 m and 1.07 m respectively,and it basically matches the maximum subsidence of engineering measurement,the accuracy of subsidence prediction theoretical model was verified,and the research results can provide new method of subsidence prediction of overburden strata and earth surface in shallow buried thick soil layer coal seam mining.