坚硬顶板工作面超前支承压力分布演化特征研究

Distribution and evolution characteristics of advanced abutment pressure in hard-roof working faces

  • 摘要: 随着开采深度增加与地质条件日趋复杂,目前针对工作面超前支承压力分布的研究难以完全适用于坚硬顶板条件。为深入揭示坚硬顶板工作面超前支承压力分布演化特征,以大同煤矿集团有限责任公司马脊梁煤矿8105工作面为工程背景,综合采用理论分析、数值模拟、现场实测方法,分析了不同工作面推进距离、回采速度和采厚对工作面超前支承压力分布的影响规律。研究结果表明:坚硬顶板工作面超前支承压力呈现明显的分区特征,按照距工作面距离由近及远可依次划分为卸压区、应力集中区、二次卸压区与原岩应力区;随着工作面推进距离增大,基本顶悬顶距离增大,工作面应力集中区内工作面超前支承压力峰值增大,二次卸压区内工作面超前支承压力谷值降低,二次卸压区范围扩展;基本顶断裂时会伴随发生顶板“反弹−回缩”效应,使得工作面超前支承压力峰值回落,工作面超前支承压力谷值回升,二次卸压区范围收缩;提高回采速度或增大采厚均会导致工作面超前支承压力峰值升高、二次卸压区范围扩展、卸压幅度增大,从而使工作面超前支承压力分区特征更明显。

     

    Abstract: With increasing mining depth and increasingly complex geological conditions, existing studies on the distribution of advanced abutment pressure in working faces are difficult to be fully applicable to hard-roof conditions. To further reveal the distribution and evolution characteristics of advanced abutment pressure in hard-roof working faces, taking the 8105 working face of Majiliang Coal Mine of Datong Coal Mine Group Co., Ltd. as the engineering background, theoretical analysis, numerical simulation, and field measurements were comprehensively adopted, and the influences of different working face advance distances, mining speeds, and mining thickness on the distribution of advanced abutment pressure were analyzed. The results showed that the advanced abutment pressure in hard-roof working faces exhibited obvious zoning characteristics, which were successively divided, from near to far from the working face, into a pressure relief zone, a stress concentration zone, a secondary pressure relief zone, and an in-situ stress zone. With the increase in working face advance distance, the cantilever length of the main roof increased, the peak value of advanced abutment pressure in the stress concentration zone increased, the valley value of advanced abutment pressure in the secondary pressure relief zone decreased, and the range of the secondary pressure relief zone expanded. When the main roof fractured, a roof "rebound–retraction" effect occurred, causing the peak value of advanced abutment pressure to decrease, the valley value to increase, and the range of the secondary pressure relief zone to shrink. Increasing the mining speed or the mining thickness both led to an increase in the peak value of advanced abutment pressure, an expansion of the secondary pressure relief zone, and an increase in the pressure relief magnitude, thereby making the zoning characteristics of advanced abutment pressure in the working face more pronounced.

     

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