煤层底板卸荷扰动断裂机制宏细观研究

发布时间：2018-07-26 20:00

【摘要】：基于断裂力学和重整化群理论,采用综合研究方法,从宏细观角度对开采扰动底板损伤岩层动态失稳机理进行了研究。结果表明,煤层回采后,底板岩层存在高应力束组成的主应力拱,最大主应力大小决定裂纹的起裂与扩展,裂纹的生长路径受控于最大主应力的方向。采场高支承压力引起岩层原始裂纹起裂,宏观上表现为底板岩层的预先剪切随机破坏;近场区域最大主应力场部分偏转,引起底板岩层中垂直应力显著降低、浅部水平应力急剧增加和斜向采空区方向产生高剪应力,迫使裂隙在原有扩展长度基础上进一步生长;工作面继续推进,采空区内底板岩层水平方向上压缩和竖向膨胀引起岩层拉破坏,当底板岩层损伤发展到临近损伤值时,极小范围的扰动被强烈放大,底板岩层由随机破坏转为"雪崩"式宏观断裂。
[Abstract]:Based on the theory of fracture mechanics and renormalization group, the dynamic instability mechanism of damaged strata of mining disturbance floor is studied from the macro and meso view by using comprehensive research method. The results show that there is a principal stress arch composed of high stress beam in the floor strata after coal seam mining. The crack initiation and propagation are determined by the maximum principal stress, and the growth path of the crack is controlled by the direction of the maximum principal stress. The initial crack initiation caused by high supporting pressure in stope is shown as pre-shear random failure of bottom rock layer macroscopically, and partial deflection of maximum principal stress field in near field region, which results in significant reduction of vertical stress in bottom rock layer. The sharp increase of shallow horizontal stress and the high shear stress in the direction of inclined goaf force the crack to grow further on the basis of the original extended length, and the face continues to advance, The horizontal compression and vertical expansion of the bottom strata in the goaf lead to the tensile failure of the strata. When the damage of the bottom rock develops to near the damage value, the disturbance in the minimum range is strongly amplified. The floor rock layer changed from random failure to "avalanche" macroscopic fracture.
【作者单位】：安徽理工大学深部煤矿采动响应与灾害防控安徽省重点实验室;安徽理工大学能源与安全学院;山东省煤炭技术服务有限公司;中国矿业大学(北京)资源与安全工程学院;
【基金】：国家自然科学基金煤炭联合基金重点项目(U1361208) 深部煤矿采动响应与灾害防控安徽省重点实验室开放基金项目(KLDCMERDPC13103) 安徽理工大学博士基金项目;安徽理工大学青年教师科学研究基金重点项目(12859)
【分类号】：TD821

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