Based on FLAC3D numerical simulation software, research was made on the mining effect of the overlying coal and rock mass after the extraction of the lower protective seam, and the stress distribution characteristics and displacement change laws of the overlying coal and rock mass and the pressure-relief range of the protected seam were obtained. The research results showed that the pressure-relief degree, the stress concentration degree and the pressure-relief range of the overlying coal and rock mass were all related to the seam interval, if the seam interval was larger, the pressure-relief degree and the stress concentration degree were smaller, and if the position of the largest stress concentration was closer to the goaf, the corresponding pressure-relief range was also smaller. For this reason, the protected seam was divided into several zones from the angle of the stress and strain or the gas flow, and the horizontal displacement law of the overlying coal and rock mass was summarized. The engineering practice showed that to drill closer holes in the non-full pressure relief zone and carry out powerful gas drainage for a long time can eliminate the coal and gas outburst hazard in the non-full pressure relief zone and achieve the purpose of the boundary expansion of the pressure-relief range.% 基于FLAC3D数值模拟方法，研究了下保护层开采上覆煤岩体的采动效应，得出下保护层开采上覆煤岩体的应力分布特征、位移变化规律和被保护层的卸压范围。研究结果表明，上覆煤岩体卸压程度、应力集中程度和卸压范围均与层间距有关，层间距越大，卸压程度和应力集中程度均越小，最大应力集中位置越倾向于采空区，相应的卸压范围也越小。从应力应变和瓦斯流动角度，将被保护层进行了划分，并对上覆煤岩体的水平移动规律进行了总结。工程实践表明，在非充分卸压区施工密集钻孔，经较长时间的强化抽采，可消除非充分卸压区的突出危险性，达到被保护层扩界的目的。
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