巨厚煤层综放开采顶煤体冒放分区演化特征研究

The western area of our country especially Xinjiang area distributed a large number of thick coal seam over 20m. After the eleven five science and technology research, it was successfully achieved the entire layer with fully mechanized caving mining of 14~20m thick coal seam. whether the huge thick coal seam more than 20m’s could achieve the limit caving height of the whole layer under fully mechanized caving mining, at present, the domestic and foreign relevant research work still need further . With thick seam of body as the research object, the project study in the aspects of the thick top coal caving characteristics..This project comprehensively applied laboratory experiments, similar simulations, theoretical analysis and numerical simulation. Mechanical parameters and damage characteristics of huge thick coal specimen under different scales were determined by laboratory experiments. The dynamic mechanism to start the development of crack and crushing for top coal were analyzed by theoretical method. The partition evolution characteristics of top coal development was researched by similar simulation. The damage variation of spatial distribution for huge thick top coal were analyzed by three-dimension numerical simulation. On the basis of this , Evolution characteristics of the top coal caving partition for Fully mechanized top coal caving in huge thick coal seam & Determination of the limit caving height were obtained. The Project results have important theoretical and practical significance for huge thick coal mining.

我国西部地区尤其是新疆地区分布着大量的20m以上巨厚煤层，经过“十一五”科技攻关，已经成功实现14~20m特厚煤层的整层综放开采。而对于20m以上巨厚煤层能否实现整层综放开采以及极限放煤高度的探讨，目前国内外相关的研究工作仍需进一步深入。项目以巨厚煤层综放开采顶煤体为研究对象，从巨厚顶煤体冒放特性角度展开研究。.项目采用实验室实验、相似模拟、理论分析和数值模拟等多学科交叉的研究方法，通过实验室实验测定巨厚煤层不同尺度煤样试件的力学参数及破坏特征，通过理论分析巨厚煤层开采顶煤体裂隙发展及破碎发展的动力机制，通过相似模拟分析巨厚煤层开采顶煤体裂隙发展的分区演化特征，通过三维数值模拟分析巨厚煤层顶煤体破坏的空间分布特征及变化规律，最终得到巨厚煤层综放开采顶煤体冒放的分区演化特征与极限放煤高度的确定方法。项目研究成果对于巨厚煤层开采具有重要的理论和现实意义。

针对巨厚煤层（大于20m）能否进行综放开采一次采全高问题，项目聚焦大尺度顶煤体的冒放性，采用实验室实验、数值模拟、相似模拟和理论分析相结合的研究方法，对巨厚煤层综放开采顶煤体破坏的演化过程进行了深入研究。主要开展了综放开采顶煤体破坏的尺度效应；综放开采顶煤破坏发展的动力机制；综放开采顶煤体冒放的分区演化规律；综放开采极限放煤高度的确定方法等方面的研究。结果表明：①不同高径比煤样在三轴压缩试验中都存在孔隙压密—线弹性—塑性—破坏四个阶段，随着试件高径比的增大各阶段的表现特征为：孔隙压密阶段试件的变形量增大，线弹性阶段试件的弹性模量减小，塑性阶段试件的轴向应变增大，破坏阶段试件的峰后应力跌落变慢且残余承载强度逐渐增大。试件的最终破坏形态随高径比的增加从以压裂破坏为主逐渐过渡到以剪切破坏为主，且剪切破裂面下部裂隙发育充分，剪切破裂面上部裂隙不发育。②巨厚煤层综放开采过程中，超前支承压力对中、下位顶煤体内裂隙的扩展和顶煤体的破坏起着关键性作用;控顶区内支架的反复支撑加剧了下位顶煤体的破坏。③基于特厚顶煤体上、中、下位明显的不同破坏、冒落特征，提出了巨厚煤层综放开采顶煤体“三带”结构模型，即自下而上分别为“散体带”、“块体带”、“裂隙梁带”，“三带”结构形成的动力机制与冒落特征:下位顶煤体受超前支承压力与支架反复支撑作用形成“散体带”，随采随冒，易回收;中位顶煤体受超前支承压力与上位顶煤体结构的挠曲变形压力作用形成“块体带”，冒落块度不均，但基本都可回收;上位顶煤体的受顶板结构的作用形成“裂隙梁带”，周期性滞后垮断，难以全部回收。④根据特厚顶煤体“三带”的结构模型，得到顶煤体“三带”各个分带厚度的确定方法，据此对极限放煤高度进行评价。项目研究成果进一步提高了对于巨厚煤层综放开采特厚顶煤体破碎机理及冒放特性的认识，具有一定的科学意义与应用前景。