深井高应力浸水孤立煤体蠕变失稳型冲击地压机理研究

    Creep instability rock burst mechanism of high-stress isolated coal immersed in water

    • 摘要: 以赵楼煤矿七采区南部水仓联络巷冲击显现为背景,采用理论分析、数值模拟、现场实测等方法,研究了高应力浸水孤立煤体蠕变失稳型冲击地压机理。浸水孤立煤体承载应力主要呈现从“双峰”形到“马鞍”形再到“平台”形最后到“单峰”形的蠕变演化规律;基于burgers模型,引入了含水损伤变量,建立了孤立煤体弹性区集中应力估算力学模型,揭示了高应力浸水孤立煤体蠕变失稳型冲击机理:孤立煤体在水仓积水的不断弱化作用下,强度逐渐降低直至残余强度,其承载能力也随之下降,导致应力集中由塑性区向弹性区转移,当弹性区承载集中应力超过其失稳阈值时,容易诱发冲击地压;提出了高应力浸水孤立煤体蠕变失稳型冲击的防治对策:降低孤立煤体平均承载应力,增加孤立煤体综合抗压强度,必要时针对孤立煤体附近的巷道进行充填处理。

       

      Abstract: Based on the rock burst occurrence of the south water sump connecting roadway in the seventh mining area of Zhaolou Coal Mine, the mechanism of creep instability rock burst of high stress isolated coal immersed in water was studied by means of theoretical analysis, numerical simulation and field measurement. The main conclusions are as follows: the bearing stress of isolated coal immersed in water mainly presents the creep evolution law from “bimodal-shaped” to “saddle-shaped”, then to “platform-shaped” and finally to “unimodal-shaped”. Based on the burgers model, a water damage variable was introduced to establish a mechanical model for estimating the concentrated stress in the elastic zone of isolated coal, revealing the creep instability impact mechanism of high stress isolated coal immersed in water. Under the continuous weakening effect of water accumulation in the mine sump, the strength of isolated coal gradually decreases until residual strength, and the bearing capacity also decreases, leading to the transfer of stress concentration from the plastic zone to the elastic zone. When the concentrated stress in the elastic zone exceeds its instability threshold, it is easy to induce rock burst. Based on this, the prevention and control measures for the creep instability impact of high stress isolated coal immersed in water were proposed: reducing the average bearing stress of the isolated coal, increasing the comprehensive compressive strength of the isolated coal, and filling the tunnels near the isolated coal when necessary.

       

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