The mining spatial structure of isolated island face in extra-thick fully mechanized top-coal caving mining is unique, which leads to a complex mining stress distribution and serious safety hazards. In this study, combined with a specific engineering example, the mining stress distribution characteristics of isolated island face are expounded, and a bearing structural mechanical model of the continuous beam of overlying strata is established using elastic–plastic mechanics theory. The mechanical equations of the mining stress distribution and failure depth of coal–rock mass are then obtained. Comparison of theoretical calculation results with numerical simulation and field measurement results shows basically consistent stress distribution characteristics. The derived mechanical equations can provide an estimation method for the analysis of mining dynamics on isolated island face in extra-thick fully mechanized top-coal caving mining. The following conclusions are acquired. The coal–rock mass should bear not only the lateral mining superposition influence but also the advance mining influence in front of the coal wall, so the isolated island face is in the complex environment of multiple mining stress superposition. In the mining process, the maximum advance mining stress concentration factor is 4.0–6.0 and is located at the upper and lower ends of the isolated island face. The lateral mining failure depth of the coal wall of the isolated island face increases by 2.0–5.0 m under the influence of advance mining. Therefore, compared with the nonisolated island face, the mining pressure appearance is intense. The mining influence in the range of 20–30 m of the upper and lower ends is intense, and the mining stress in this area is characterized by “cone distribution.” This zone is an important hidden danger area with coal–rock mass mining instability on isolated island face, which requires special attention to avoid mining disasters. According to the analysis of the influencing mining factors and laws of isolated island face, it is concluded that the longer the isolated island face size is, the closer the goaf size on both sides of the isolated island face is, the smaller the coal seam buried depth is, the better the mechanical conditions of coal and rock medium are, and the smaller the mining height of coal seam is, the more favorable the safe mining of isolated island face is.

中文翻译：

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特厚综放开采孤岛工作面开采应力传递力学分析

特厚综放开采孤岛工作面开采空间结构独特，开采应力分布复杂，安全隐患严重。本研究结合具体工程实例，阐述了孤岛工作面开采应力分布特征，利用弹塑性力学理论建立了上覆地层连续梁的承载结构力学模型。进而得到煤岩体开采应力分布和破坏深度的力学方程。理论计算结果与数值模拟和现场实测结果对比，应力分布特征基本一致。推导出的力学方程可为特厚综放放顶煤孤岛工作面开采动力学分析提供一种估计方法。得到以下结论。煤岩体既要承受横向开采叠加影响，又要承受煤壁前方的超前开采影响，因此孤岛工作面处于多重开采应力叠加的复杂环境中。在开采过程中，最大超前开采应力集中系数为4.0～6.0，位于孤岛工作面上下两端。在超前开采的影响下，孤岛工作面煤壁横向开采破坏深度增加2.0～5.0 m。因此，与非孤立岛面相比，采矿压力显现强烈。上、下端20～30 m范围内开采影响强烈，该区开采应力具有“锥状分布”特征。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。上、下端20～30 m范围内开采影响强烈，该区开采应力具有“锥状分布”特征。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。上、下端20～30 m范围内开采影响强烈，该区开采应力具有“锥状分布”特征。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。且该区开采应力具有“锥体分布”特征。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。且该区开采应力具有“锥体分布”特征。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免发生开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。该带是孤岛工作面煤岩体开采不稳定的重要隐患区，需要特别注意避免发生开采灾害。根据孤岛工作面影响开采因素及规律分析，孤岛工作面尺寸越长，孤岛工作面两侧采空区尺寸越接近，埋藏煤层越小。深度越大，煤岩介质的力学条件越好，煤层开采高度越小，越有利于孤岛工作面的安全开采。