两柱掩护式综放支架与围岩相互作用相似模拟研究

Analog simulation of the interaction between a two-leg sub-level caving shield support and the surrounding rock

基于两柱掩护式综放支架新架型,采用大比例相似模拟实验,研究了工作面顶煤的变形破坏特征及支架与围岩相互作用规律,分析了顶梁前后比和支架工作阻力对支架位态和端面顶煤稳定性的影响规律.结果表明:随顶煤硬度减小,控顶区顶煤和两柱掩护式综放支架位态稳定性同时下降;顶煤较软时,放煤区和端面区顶煤的失稳并不断扩大直至贯通是导致支架-围岩系统失稳的原因,提出了顶煤双区失稳的概念;在软煤条件下,支护的关键是通过控制放煤量限制放煤区顶煤的垮落线前移,提高支架支护质量,控制端面冒顶,实验工作阻力设定值由2.7MN增加到5.5MN,端面冒顶高度由2.13m减小到1.66m,顶梁前后比设定值由2.38减小到1.49时,端面冒顶高度由1.75m减小到0.915m,同时顶梁回转角度变化由16.8°减小到1.2°.

Large scale analog material models were used to study the deformation and destruction of the top coal and the interactions between the supports and the surrounding rocks.A new support structure for top-coal-caving based on a two-leg sub-level caving shield was examined.The effects of beam pro-to-post ratio and support working resistance on the state of the supports and the fall of the roof in the tip-to-face area were analyzed.The results show that a decline in the hardness of the top-coal causes instability in it and subsequent serious problems with the supports.The extension of the fall zone in the tip-to-face area and drawing zone is the main cause of destabilization of both the two-leg sub-level caving shield support and the surrounding rock.The concept of top-coal two-zone destabilization is put forward as the key factor affecting the supports and surrounding rock.It is important in soft coal faces to prevent the extension of the top-coal caving line by controlling the caving,improving the supports,and decreasing roof fall in the tip-to-face area.The fall height in the tip-to-face area may be decreased from 2.13 m to 1.66 m under some geologic conditions when the support working resistance is increased from 2.7 MN to 5.5 MN.When the beam pro-to-post ratio is decreased from 2.38 to 1.49 the fall height decreased from 1.75 m to 0.915 m and the top beam rotation angle decreased from 16.8 to 1.2 degrees.