采动底板断层活化效应现场实测与矿压底板响应研究

    IN-SITU MEASUREMENT OF THE EFFECT OF FAULT ACTIVATION AND MINE PRESSURE RESPONSE IN THE FLOOR TO SEAM MINING

    • 摘要: 为了研究采动底板断层活化导水效应问题,采用现场应力和水压力实测方法,选择典型工作面在断层带内及其上下盘和完整地段共布设了5个测孔,进行采动过程中测孔内附加应力和水压力的跟踪监测。结果发现,完整和有断层底板附加应力均可分为稳定不变、缓慢发展和快速增加等3个阶段,最大值位于完整底板内。完整底板水压力波动大,对应位置水压力值比断层带附近的均大。随着工作面推进,断层带上下盘及内部的3个测孔的水压力有一定程度波动,但总体上来看,变化不大,且水压值均很小,认为工作面在回采过程中被监测的断层没有发生活化迹象。综合对比分析,在矿山压力作用下断层带处和完整底板处附加应力和水压力变化具有一定关联性和差异性,采前应力集中范围方面两者均表现出很好的一致性,但在采动底板矿山压力显现方面,附加应力的响应比水压力更为显著,水压力变化整体上分为两个阶段,而附加应力变化可分为3个阶段,附加应力变化在一定程度上更好地反映了采动矿压在开采煤层底板传播分区响应特征。研究方法和结果对地质构造复杂区域矿山带压开采超前预警具有很好的参考价值。

       

      Abstract: To study the water-conducting effect of activated floor faults caused by mining,in-situ stress and water pressure measurement methods were selected. Five boreholes were designed in a typical working face,including within the fault zone,in the hanging wall and footwall of the fault,and in the intact zone. Additional stress and water pressure were monitored during the advancement of the working face. The results show that the variation in additional stress exhibited three stages: a stable and unchanged stage,a slow development stage,and a rapid increase stage,with the maximum value occurring in the intact floor. Water pressure showed the greatest fluctuation and reached the highest value in the intact zone. In the three boreholes near the fault zone,water pressure fluctuated to a certain extent as the working face advanced,but the overall fluctuation was small and the pressure remained very low. This indicates that no signs of fault activation occurred during the mining process of the working face. Through comprehensive comparative analysis,it was found that changes in additional stress and water pressure at the same depth in the fault zone and the intact floor under mining pressure exhibit both correlations and differences. Both parameters showed good consistency within the stress concentration zone prior to mining,but additional stress reflected the manifestation of mining-induced pressure more clearly than water pressure. The variation in water pressure could be divided into two stages,whereas additional stress variation exhibited three stages. To a certain extent,additional stress better reflects the propagation-zone response characteristics of mining-induced pressure in the coal seam floor. These ideas and results can be applied to advance warning of mining above confined aquifers in complex geological structure zones.

       

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