倾斜-急倾斜煤层群保护层煤柱蠕变损伤对保护范围的影响规律

Based on the innovative academic idea that the mid-pillar segregating mining sections in the protective seam can be modeled as "elastic-plastic deformation body" instead of "rigidity body" in the steep protective seam mining, focuse would be taken in this study on its effect of elastoplastic creep property on the protected range. On the basis of elastoplastic creep dynamic failure theory, the hybrid deformation property, strength property and failure mode of the pillar under the combined condition of condense and shear would be investigated. With theoritical analysis and deformation index of the pillar, both of the degree of influnce of the elastoplastic creep property on protected range and the varing law of protected range due to change of coal seam dip angle would be studied, seeking for a scientific and field verified methology of determination of the prected range considering these two factors in the protective coal seam mining. With the introduction of this metholody, the coal resources can be recovered to the best of precision, safety and reasonableness. This study would show its important scientific implication in improvement of the protective coal seam safety mining theory as well as the regional outburst prevention measures.

从倾斜-急倾斜煤层群保护层开采区段中间条带隔离煤柱由以前的“不变形刚体”作为“弹塑性变形体”这一新的学术思想出发，开展倾斜-急倾斜煤层群下保护层开采区段煤柱弹塑性蠕变损伤特性对被保护层保护范围影响研究。采用弹塑性蠕变损伤理论，探求倾斜-急倾斜煤层群下保护层开采区段中间条带隔离煤柱在压剪综合作用下的弹塑性蠕变损伤复合变形特性、强度特性和破坏形式；采用矿山压力理论和变形指标法，探求倾斜-急倾斜煤层群下保护层开采区段中间条带隔离煤柱弹塑性蠕变损伤特性对被保护层保护范围影响程度和倾斜-急倾斜煤层群不同倾角条件下保护范围的变化规律，提出弹塑性隔离煤柱影响下和不同煤层群倾角下保护层开采保护范围划定的科学方法，并进行现场工程验证。该研究有利于最大限度的精准、安全、合理开采煤炭资源，是拓展煤层群保护层开采研究的一种新思路，对完善煤层群保护层安全开采理论体系和煤层群保护层开采区域防突措施具有重要的科学意义。

针对倾斜-急倾斜煤层群下保护层开采区段煤柱弹塑性蠕变损伤变形破坏特性对被保护层保护范围影响机制，采用弹塑性蠕变损伤理论，研究了倾斜-急倾斜煤层群下保护层开采区段中间条带隔离煤柱在压剪综合作用下的弹塑性蠕变损伤复合变形特性和煤柱影响下的采空区顶底板岩层损伤破坏规律；根据被保护层内应力下降指标法确定了倾斜-急倾斜煤层群下保护层开采区段中间条带隔离煤柱对被保护层保护范围影响程度和煤层群不同倾角条件下保护范围的变化规律，并对研究结果进行了现场工程验证。研究结果表明：煤柱的弹塑性损伤变形特性对被保护层保护范围具有重要影响，即便煤柱完全损伤，在煤层顶底板闭合条件下形成了围压条件，使得煤柱仍有较大的承载能力，因此在被保护层内形成一定区域的未保护范围；由于煤层倾角加大后，煤柱下缘的破碎体容易跨落到采空区，因而倾角越大被保护层的未保护范围就会减小甚至消失。研究结果对完善煤层群保护层安全开采理论体系和煤层群保护层开采区域防突措施具有重要的科学意义。