【作者】 曹安业；

【导师】 窦林名； LuoXun；

【作者基本信息】 中国矿业大学 ， 采矿工程， 2009， 博士

【摘要】 作为煤岩体震动在采掘空间内的动力显现,冲击矿压的发生与采动煤岩破裂密切相关。因此,冲击矿压有效预测及治理目标的实现,煤岩震动震源破裂机理及其冲击破坏效应的研究显得至关重要。论文围绕矿井采动煤岩冲击破裂的震动效应问题,采用理论分析、实验室物理模拟、数值模拟分析、现场试验和工程实践等方法,研究了采动诱发煤岩震动的震源破裂机理,揭示了矿震辐射能量的传播模式与衰减规律,分析了矿震动载的诱冲机理及其对巷道围岩冲击破坏效应的影响因素,并提出了煤岩冲击的预测及防治对策,最后在工程实践中进行了实证研究。煤矿井下采掘后,采场或巷道周围煤岩体要产生破裂、运动。其中:顶板弯拉断裂、冒落、离层等具有典型拉伸破裂特征;顶板回转失稳、煤柱压缩破裂等具有典型内爆破裂特征;而顶板剪切破裂、岩块滑移失稳、煤柱动态冲击和断层“活化”等则具有典型剪切破裂特征。以此,构建了煤岩震动震源等效力与震动远场位移的关系矩阵,建立煤岩震动的等效震源模型,研究了其震动位移场及能量辐射特征,揭示煤岩震动间的震源破裂机理差异,并根据震动波场特征进行煤岩震动的分类。实验室模拟研究并比较分析了顶板、煤(矿)柱和断层型等煤岩冲击破裂的微震效应及波场特征。结果表明,大尺度岩板主断裂、两次次断裂分别符合顶板水平拉伸、滑移和回转失稳的位移波场特征;弱、强冲击倾向性煤岩试样压缩受载分别近似满足煤(矿)柱内爆和动态冲击破裂的波场特征;且岩板主、次断裂,煤岩样前兆破裂、主震动间随破裂尺度增大,微震效应主要呈振幅增加、主频降低的演变规律。采用矩张量反演方法进行采动煤岩震源破裂机理的量化研究。结果表明,采用P、S波,尤其是P、SH波或P、SV、SH波的的震动位移场组合进行震源矩张量的最小二乘线性反演,可确保反演结果较好反映采动煤岩冲击破裂的震源机理和破裂特征。现场进行了爆破震动试验及Siroseis微震实测工作,对冲击震动波在采动煤岩体中传播的微震效应进行研究。结果表明,随采空区跨落、破裂范围扩大及覆岩性质的强度弱化,震动P波平均波速、峰值振幅平均值及P波初至平均频率等微震参量均有较大程度降低。理论分析了矿震激发震动波能量的传播模式和衰减特征,揭示了传播至巷道围岩处矿震残余动载的诱冲机理,数值模拟研究了矿震动载对巷道围岩冲击破坏效应的影响规律,进而提出了煤岩冲击预测及防治对策。在具有强矿震危险的鲍店103上02工作面和高冲击危险的华亭250102工作面进行了现场实践,基于SOS微震监测,对比分析各自开采地质条件下,采动诱发不同能量级别煤岩震动的震源破裂机理及强矿震动载对巷道围岩的不同冲击破坏效应,为现场煤岩冲击的预测及防治提供依据。更多还原

【Abstract】 As the dynamic behavior of mining-induced tremor of coal-rock mass in longwall faces or roadways, rock burst is closely related to the failure of coal-rock mass associated with mining. Therefore, studies on the failure mechanisms and burst effects of mining-induced tremors are quite essential for the forecasting and prevention of rock bursts. Focusing on the seismic effects of the burst and failure of coal-rock mass associated with mining, this paper studied the failure mechanisms of typical mining-induced tremors, revealed the transmission and attenuation rules of the seismic energy radiated by tremors. Additionally, the mechanism of rock burst induced by tremor, and the influential factors of the burst effort to surrounding rock of the roadway, as well as the corresponding forecasting and control method were analyzed by theoretical analysis, laboratory physical simulation experiment, numerical simulation, field testing, and engineering practice as well.Mining-induced coal and rock fracturings or movements near the roadways or longwall faces will be generated by mining activity underground. Generally, the tremors induced by roof tensile fracturing, caving and bed separation have a typical tensile failure source characteristics, the tremors induced by roof rotation and compressive fracturing of coal pillar show a typical implosive failure characteristics, while the tremors induced by roof shear fracturing, rock block sliding, dynamic bursting of coal pillar and fault reaction are characterized by typical shear fracturing source model. Based on above, equivalent source models of mining-induced tremors were established based on the construction of the relation matrix between the equivalent force and the far-field displacement, then the characteristics of seismic displacement and radiated energy were studied, and the differences of failure mechanism of typical mining-induced tremors were revealed as well. Finally, different tremors were classified according to the differences of seismic displacement characteristics.Laboratory-scaled experiments were carried out to analyze the seismic effects and displacement field characteristics of roof, coal pillar, and fault burst and failure modes systematically. Studies indicate that the displacement fields of main shock, two aftershocks of the rock block conform to roof horizontal tensile fracturing, sliding and rotation instability, respectively, and the weak and strong burst-prone coal/rock samples under uniaxial compression approximately conform to the implosive failure and dynamic bursting of coal pillar, respectively. In addition, the seismic effects take on the evolution rules of amplitude increasing and dominant frequency decreasing with the extension of the failure radius.Moment tensor inversion method was used to quantitatively analyze the failure mechanisms of mining-induced tremors. Studies show that a satisfying inversion result of failure mechanism and fracturing characteristic deternimantion of mining-induced tremor can be achieved by least-square linear inversion of moment tensor, using the combination of P, S-wave displacement fields, especially P, SH-waves, or P, SV, SH-waves.Seismic effects during the transmission of seismic waves in coal-rock mass associated with mining process were studied by on-site testing and Siroseis monitoring. Results show that the average P-wave velocities, mean values of Comb. Max. Amplitudes and frequencies of the first arrivals were reduced greatly by roof caving, goafing expanding and intensity weakening of the overlying strata associated with mining process.Seismic energy transmission and attenuation modes radiated by mining-induced tremors were theoretically analyzed, and the mechanism of rock burst induced by residual dynamic load of tremor was revealed. Then, the influential factors of the burst effort to surrounding rock were simulated by using dynamic modules of FLAC2D and source-time function simulation of mining-induced tremors. Finally, the corresponding forecasting and control method of rock burst were proposed.Taking LW10302 in Baodian Coal Mine with strong tremor risk and LW250102 in Huating Coal Mine with high burst risk for the on-site practice. Based on SOS microseismic monitoring and the respective mining and geological conditions of the two mines, the failure mechanisms of mining-induced tremors with different energy levels and the seismic effects of strong tremors on the surrounding rocks of roadways or longwall faces were comparatively analyzed, which provides basis for the forecasting and prevention of rock burst.更多还原