坚硬顶板砂岩水力压裂裂缝扩展规律分析

为探究不同因素对水力裂缝扩展行为的影响，以塔山煤矿坚硬顶板砂岩为研究对象，采用扩展有限元法模拟裂缝扩展过程，分析了水平应力比、抗拉强度、泊松比、间隔时间、注液速率和裂缝间距对裂缝扩展行为的影响。结果表明：单裂缝扩展时，应力比和泊松比越大，抗拉强度越小，越有利于裂缝延伸，且稳定扩展压力越小；应力比和泊松比越小，抗拉强度越大，越有利于裂缝张开；注液间隔时间对裂缝扩展影响较小。双裂缝扩展时，注液速率和裂缝间距越大，越有利于裂缝延伸；注液速率越大和裂缝间距越小，越有利于裂缝张开；注液速率减小，裂缝间距增大，稳定扩展压力减小。针对坚硬顶板砂岩的水力压裂，此研究可为煤矿现场设计与施工提供参考和借鉴。

Analysis on the Propagation Law of Hydraulic Fracturing Cracks in Hard Roof Sandstone

The hard roof sandstone of Tashan Coal Mine is used as the research object to explore the influence of different factors on the propagation behavior of hydraulic cracks. The extended finite element method was used to simulate the crack propagation process, and the influence of horizontal stress ratio, Tensile strength, Poisson''s ratio, interval time, liquid injection rate and crack spacing on the crack propagation behavior were analyzed. The results show that: When a single crack propagates, the larger the stress ratio and Poisson''s ratio, the smaller the tensile strength, the more conducive to crack extension, and the smaller the stable expansion pressure; The smaller the stress ratio and Poisson''s ratio, the greater the tensile strength, which is more conducive to crack opening; The injection interval has little effect on the crack propagation. When double cracks propagate, the larger the liquid injection rate and crack space, the more favorable the crack extension. The larger the liquid injection rate and the smaller the crack space, which is more conducive to crack opening; The liquid injection rate decreases, the crack spacing increases, and the stable expansion pressure decreases. Aiming at the hydraulic fracturing of hard roof sandstone, this research can provide reference for the design and construction of coal mine site.