无煤柱(或小煤柱)开采已得到广泛应用，随着开采深度增加，当侧空覆岩存在坚硬岩层时，大能量动力事件频发，冲击地压显现日趋严重，已成为制约深部煤炭资源开采的主要瓶颈之一。围绕沿空侧向覆岩结构改性防冲机理与实践开展研究，主要包括：构建了沿空工作面覆岩结构力学模型，提出了上位覆岩等效载荷估算方法，揭示了下位覆岩结构特征及演化规律；获得了沿空工作面下位覆岩运动对煤体内应力的定量表征方法，提出了以煤体的静载支承应力及关键层断裂产生的扰动应力之和与煤体强度比值大小为致灾指数的覆岩致灾关键层判识方法；定义了覆岩关键结构失稳致灾力学判据，综合分析应力状态和冲击倾向性指数对“发生冲击地压”的隶属度实现了侧空覆岩致灾风险评级；给出了侧空覆岩结构改性方法及防冲流程，并在新巨龙6305工作面开展了工程实践。结果表明，6305工作面实施侧空覆岩结构主动改性后，微震事件频次增幅33.3%，平均每个事件能量降幅23.5%；煤体应力集中程度显著降低，最大降幅约27.2%；沿空巷道围岩变形量明显减小，最大减小约104.7%；侧空覆岩致灾关键层得到消除，冲击地压的可能性等级为由“很可能”降为“不可能”。

Pillarless (or small-pillar) mining method has been widely used. With increasing mining depth, the hard rock in the overlying strata leads to high stress concentration, extensive damage, and frequent high-energy dynamic events, which has become a major bottleneck in deep mining. In this study, the mechanism of rockburst prevention through the modification of lateral overlying strata was investigated. A mechanical model for lateral overlying strata was established, and an estimation method for the equivalent load of the upper overlying strata was proposed. The spatial structure characteristics and evolution of the lower overlying strata were revealed. A quantitative method for characterizing the stress in the coal seam induced by lower overlying strata movement was developed. A disaster-causing index was introduced, defined as the ratio of the combined static stress and disturbance stress from key layer fractures to coal seam strength, and a method for identifying key disaster-causing layers was proposed. The mechanical criterion for the instability of the key layer is defined, and the impact risk assessment is realized by comprehensively analyzing the membership degree of stress state and impact tendency index to “rockburst occurrence”. A method of lateral overlying strata modification and a rockburst prevention process were proposed and engineering practice was applied in the 6305 working face of the Xinjulong coal mine. The results showed that after active modification, the frequency of micro-seismic events increased by 33.3%, while the average energy of each event decreased by 23.5%. The stress concentration was significantly reduced, with the maximum reduction of about 27.2%. The deformation of the surrounding rock was significantly decreased, with a maximum reduction of about 104.7%. Moreover, the key disaster-causing layers has been eliminated, and the possibility of rockbursts was reduced from “high-likely” to “non-likely”.