浅埋煤层群大采高采场初次来压顶板结构及支架载荷研究

Research on roof structure and support resistance during first periodic weighting in shallow group coal seams

以陕北榆神矿区浅埋近距离煤层群下行开采为背景,通过物理模拟研究了下煤层工作面初次来压的顶板结构特征。近距离煤层下煤层开采时,间隔岩层顶板一般具有单一关键层,顶板初次破断形成"非对称三铰拱结构",结构上的载荷层为上煤层采空区垮落顶板。上煤层垮落顶板结构在下煤层采动后活化,与下煤层三铰拱结构共同形成"非对称三铰拱梁与拱壳载荷结构"。通过建立浅埋煤层群下煤层关键层固支梁力学模型,修正了基本顶极限垮距计算公式,确定了下煤层顶板结构块的参数。建立了煤层群下煤层开采初次来压的支架载荷计算模型,揭示了工作面顶板动压机理。基于动静载荷作用,提出了初次来压的合理支架工作阻力确定方法,为浅埋近距离煤层群开采的顶板初次来压控制提供了理论依据。

Based on the background of shallow and close coal seam group downward mining in Yulin-Shenmu mining area in northern Shaanxi, through the physical simulation of roof structure characteristics during the first roof periodic weighting in lower coal seams. In the close coal seams mining,the interval layer roof generally has a single key stratum. The roof＇s first breaking forms an ＂asymmetric three hinged arch structure＂ and the load layer on the structure is the caving roof of the upper coal seam. The caving roof structure of upper coal seam is activated after lower coal seam mining and combines with the three hinge arch structure of the lower seam together to form the ＂asymmetric three hinged arch with arch shell load structure＂. By establishing the clamped beam mechanical model of the key stratum of lower coal seam roof in the shallow coal seam group mining, the calculation formula of the ultimate collapse distance of the interval layer roof is modified and the parameters of the roof structure blocks of the lower coal seam are determined. The support static load calculation model of the first periodic weighting in lower seam mining is established. Thus, the mechanism of the roof dynamic pressure of the mining face is revealed. Based on the static and dynamic load, the method of determining the reasonable support resistance is proposed, which provides a theoretical basis for the roof first periodic weighting control in shallow and close coal seams mining.