厚硬顶板是诱发煤矿冲击地压、矿震等灾害的关键因素，其中煤层顶板发育有复合关键层厚硬顶板条件下灾害更为严重，揭示复合关键层厚硬顶板诱冲机制，构建防治技术模式迫在眉睫。

运用物理相似模拟和力学分析等方法，建立复合关键层硬顶板和其非协同破断判识方法，揭示复合关键层厚硬顶板诱冲机制，优选防冲技术模式。

结果表明：(1) 复合关键层厚硬顶板呈现“大−小”周期来压规律，来压期间声发射频次和微震能量分别为非来压的5.3倍与7.3倍；上、下位关键层厚硬顶板同步破断扰动叠加，叠合“周期”和“见方”来压效应诱发大型冲击地压灾害。(2) 建立了以中性轴线为基础的复合关键层判识模型，两层及以上关键层厚硬顶板形成复合关键层前提是梁模型横截面上剪切应力不超过对应的抗剪强度。(3) 形成了“悬臂梁”和“砌体梁”两种模式下合理破断线距离定量判识方法，提出了复合关键层厚硬顶板上、下单层和双层协同3种水力压裂卸压技术模式。(4) 分析显示下位关键层压裂主要改变了厚硬顶板关键层完整性和强度，缩短了来压步距，无法控制上位关键层“拱壳”结构大能量冲击地压；上位关键层压裂控制“大周期”破断扰动载荷，减弱了复合关键层耦合效应，大幅降低冲击地压危险性，是冲击地压主控层位，“上−下位”关键层协同压裂为最优卸压防冲模式。该研究成果将为复合厚硬顶板冲击地压地压、矿震灾害区域的精准防治提供重要依据。

Thick-hard roofs serve as the key factor inducing disasters such as rock bursts and mining-induced earthquakes in coal mines. These disasters are especially serious in the case of coal seam roofs with compound key strata. Hence, there is an urgent need to reveal the mechanisms behind the rock bursts induced by thick-hard roofs with compound key strata and to develop technical modes for the prevention and control of these rock bursts.

Using methods including physical simulation experiments on similar materials and mechanical analysis, this study developed methods for identifying roofs with compound key strata and for non-synergistic breaking of the compound key strata. Furthermore, this study revealed the mechanism behind the rock bursts induced by the roof and selected the optimal technical mode for prevention. [Results and Conclusions] Key findings are as follows: (1) Thick-hard roof with compound key strata exhibited large and small periodic weighting, with acoustic emission frequency and microseismic energy during weighting being 5.3 and 7.3 times those in the absence of weighting. The synergistic breaking of the upper and lower compound key strata led to disturbance superimposition, with superimposed periodic effects and weighing effects at square locations inducting large-scale rock bursts. (2) An identification model of compound key strata based the neutral axis was established, revealing that the prerequisite for the phenomenon that two or more key strata in the thick-hard roof form compound key strata is that the shear stress on the cross-section does not exceed the corresponding shear strength in the beam model. (3) A method for quantitatively determining the distances of the breaking lines under the cantilever-beam and masonry-beam models was developed. Furthermore, three hydraulic fracturing and pressure relief technical modes were proposed: the fracturing of the upper key stratum, the fracturing of the lower key stratum, and the synergistic fracturing of both strata. (4) The results indicate that the fracturing of the lower key stratum primary, despite changing the integrity and strength of the lower key stratum and shortening the step distance in periodic weighting, failed to control the energetic rock bursts caused by the arched shells of the upper key stratum. The fracturing of the upper key stratum, the predominant layer influenced by rock bursts, controlled the loads induced by breaking disturbance in large weighing cycles, weakened the coupling effects between the compound key strata, and greatly reduced the dangerousness of rock bursts. In contrast, the synergistic fracturing of both strata was identified as the optimal mode for pressure relief and rock burst prevention. The results of this study will provide an important basis for the precise prevention and control of areas potentially struck by disasters such as rock bursts induced by thick-hard roofs with compound key strata and mining-induced earthquakes.