顶板初始损伤对煤岩组合体破坏性态及能量演化的影响

Influence of initial roof damage on destructive state and energy evolution of coal-rock mass

采用CASRock对煤岩组合体开展单轴压缩破坏过程数值模拟试验,分析顶板初始损伤对煤岩组合体力学行为的影响。结果表明:(1)顶板初始损伤对煤岩组合体力学行为的影响程度与顶板中初始裂隙的几何分布密切相关,随着裂隙与水平面夹角增大,煤岩组合体由延性破坏向脆性破坏转变,同一裂隙倾角下,随着裂隙长度增加,煤岩组合体由脆性破坏向延性破坏转变,且裂隙与水平面夹角越小、长度越长、距离煤层越近对煤岩组合体力学行为影响越大,越能主导煤岩组合体的力学行为,煤体越不易发生破坏;(2)顶板含多裂隙时裂隙主导煤岩组合体力学行为能力更强,当顶板初始损伤较严重时,初始的裂隙网络会形成应力集中区,导致其对煤岩组合体力学行为影响能力变强;(3)单轴压缩条件下,劈裂破坏是主要的破坏形式,顶板初始损伤对煤岩组合体强度与变形能力的提升作用较强,当顶板裂隙对煤岩组合体力学行为影响较大但不主导其力学行为时,其释放能量效果较好,顶板初始损伤在一定程度上增强了对煤层的保护效果。

Through the numerical test of uniaxial compression failure process of coal and rock mass by using CASRock,the influence of initial damage of roof containing cracks on mechanical behavior of coal seam was analyzed.The results showed that:(1)The initial damage degree of the impact on the mechanical behavior of coal seam roof and the roof of the initial crack was closely related to the geometric distribution,with the in-crease of fractures and the horizontal angle,the coal and rock assemblages from the ductile fracture to brittle failure,under the condition of the same fracture dip,with the increase of crack length,assembly from the brittle fracture to ductile fracture,The smaller the angle between the fracture and the horizontal plane,the longer the length,and the closer the distance to the coal seam,the greater the influence on the mechanical behavior of the combination,the more dominant the mechanical behavior of the combination,and the less likely the coal seam was to be destroyed;(2)The mechanical behavior of coal and rock mass dominated by cracks was stronger when the roof contained multiple cracks;When the initial damage of the roof was serious,the initial fracture network would form a stress concentration area,leading to its strong influence on the me-chanical behavior of the composite body;(3)Under the condition of uniaxial compression,fracturing was the main damage form of roof combination of initial damage on strength and deformation ability of ascension effect was stronger,when the roof fracture with combination had a greater influence on the mechanical behavior,but not dominated the combination mechanical behavior,its release can effect was good,roof initial damage enhanced the protective effect of coal seam to a certain extent.