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掘进工作面直流电法超前探测技术问题探讨

Discussion on problems of direct current advance detection method in roadway driving face

  • 摘要: 直流电法是目前煤矿掘进工作面超前探测的主要方法,探测效果直接关系煤矿安全生产,对其探测效果有必要做进一步的研究。针对球壳理论,建立了点电源一侧含异常体模型并计算了三维电位值,分析了点电源一侧存在异常体时,在点电源另一侧的电位分布情况,建立了掘进工作面前方不同距离含立方异常体和无限大板状异常体模型;通过数值模拟计算,研究了视电阻率异常范围和异常体实际大小的关系,以及视电阻率异常位置与异常体实际位置的关系;对位于测线不同位置的异常体模型进行了数值模拟计算,研究了该方法对测线前方和对测线下方异常体的探测灵敏度;建立了典型含水体探测模型,进行了仿真计算,并基于几何交汇原理成图,探讨了典型含水体探测效果;最后介绍了2个典型的未成功探测工程实例,将探测结果和前方已知地层富水情况进行了对比说明。研究结果表明:点电源一侧存在异常体时,在点电源另一侧不会产生突变的异常,球壳理论是不准确的;视电阻率异常范围远大于异常体实际大小,视电阻率异常位置与异常体实际位置亦不对应;超前探测结果主要为巷道底板而不是巷道前方地质情况的反映;直流电法巷道掘进工作面超前探测方法探测精度和分辨率均较低,成果图中难以有效识别异常体的大小和位置,现有掘进工作面直流电法超前探测方法的探测原理和数据处理解释方法是不准确的。

     

    Abstract: Direct current method is the main method for advanced detection of the current mining face of coal mines. The detection effect is directly related to the s afety of coal mines. In view of the spherical shell theory,an anomalous body model on the side of the point source was established and the three-dimensional potential V alues were calculated,the potential distribution on the other side of the point source was analyzed when there was an abnormal body on the point source, and a model W ith cubic anomalies and infinite plate-shaped anomalous bodies at different distances was established in front of the working face; Through numerical simulation calcula tions,the relationship between the apparent resistivity anomaly range and the actual size of the anomalous body was studied,and the relationship between the apparent resistivity anomalous position and the actual position of the anomalous body was analyzed; the detection sensitivity of this method to the geological bodies in front and below the survey line was established; a typical water-body detection model was established,simulation calculations were performed,and mapping based on the geomet ric intersection principle was used to explore the effects of typical water-body detection; Two typical unsuccessful exploration engineering examples were introduced,the detection results and the known ground ahead the water-rich condition of the layer were compared and explained. The results show that: anomalous body set on one si de of the point source cannot generate a sharp electric field change on the other side,and the"spherical shell"theory is inaccurate; the abnormal range of apparent resist ivity is much larger than the actual size of the abnormal body,and the abnormal position of the rate does not correspond to the actual position of the anomalous body; th e advanced detection results are mainly a reflection of the roadway floor rather than the geological situation in front of the roadway; the detection accuracy and resoluti on of the advanced detection method of the roadway working face of the direct current method are low,which is difficult to achieve in the result map. Overall,the theory and data processing and interpretation of direct current method used in roadway advanced detection are inaccurate.

     

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