地质异常区域多工作面开采结构演化及冲击地压防治

Structure evolution and rockbursts prevention in multi-face mining in geological anomaly area

针对某矿地质异常体区域多工作面开采覆岩空间结构多变、致灾因素复杂现象,以该矿实际地质赋存条件和开采技术条件为工程背景,采用理论分析、数值模拟等方法,研究了地质异常体区域覆岩空间运移结构变化规律和支承压力分布特征,以单层弯曲薄板为例建立了不同开采阶段板的力学模型,揭示了不同开采阶段板结构弯曲能量释放特征,基于结构调控理论提出了减小厚硬岩层垮断跨度的初末采冲击地压防治措施,主要得到以下结论:(1)随着多工作面依次开采,在地质异常体区域依次经历了“一”字形→“S”形→短“Ω”形→不规则“Ω”形→长“Ω”形→“O”形覆岩空间结构演变,丰富了覆岩空间结构的类型;(2)受地质异常体影响,多工作面开采过程中承受了更多次的初次来压和“见方”来压,该区域顶板垮断动载扰动与支承压力分布更加复杂多变,容易造成工作面宽煤柱整体失稳性冲击危险;(3)基于单层弯曲薄板力学模型,得到了不同板结构弯曲能随边长呈指数或线性增大,且相对于固支边,自由边对弯曲能影响更大的结论;(4)对防冲预卸压及解危措施进行了效果检验,在工作面开采过程中没有出现微震大能量事件且煤体应力维持稳定,结构调控措施基本保障了地质异常体区域多工作面开采初末采冲击地压防治效果。

Aimed at the phenomenon of variable overburden spatial structures and complex disaster factors in multi-face mining in a geo-logical anomaly area of a mine,taking the actual geological occurrence conditions and mining technology conditions as the engineering background,this paper studied the changes rule of overburden spatial migration structures and the distribution characteristics of abutment pressure in the geological anomaly area by theoretical analysis and numerical simulation.Taking single-layer bending thin plate as an ex-ample,mechanical models of plates at different mining stages were established,and the characteristics of bending energy release of plates at different mining stages were revealed.Based on the structural regulation theory,the prevention measures of rock burst at the beginning and end of mining were proposed to reduce the collapse span of thick and hard rock strata.The main conclusions were as follows:①With the successive mining of multiple faces working,the overburden spatial structure evolution of“-”→“S”→short“Ω”→irregular“Ω”→long“Ω”→“O”→shaped overburden spatial structures has been experienced in the area of geological anomalies successively,enriching the types of overburden spatial structure;②Due to the influence of geological anomalies,more initial pressure and“square”pressure are borne in the mining process of multiple faces working.The dynamic load disturbance and abutment pressure distribution of roof collapse in this area were more complex and changeable,which were easy to cause the risk of overall instability rock bursts of wide coal pillar;③Based on the mechanical model of single-layer bending thin plate,it was concluded that the bending energy of different plate structures increased exponentially or linearly with the length of the side,and the free edge had a greater influence on the bending energy than the fixed edge;④The effect test of the pre-pressure relief and danger relief measures showed that there were no big micro-seismic energy events in the working face mining process and the coal body stress remained stable.The structural control measures basically guaranteed the prevention effect of rock burst at the beginning and end of the multi-working face mining in the geological abnormal area.