回采工作面断层构造无线电波反射测量方法研究

The reflected radio wave method for detecting coal seam faults in mining face

矿井无线电波勘探可用于煤层地质构造探查,凭借其轻便和效果好等优势,成为煤层地质构造探查的常规和必备手段。现阶段无线电波信号在煤层中的能量衰减较快,大宽度煤层工作面透射无线电波探测面临制约。基于此,提出煤层工作面无线电波反射勘探方法。首先,数值模拟构建二维含煤地层电性模型,对无线电波Hx分量信号的场强值进行分析。模拟结果显示:无线电波在正常煤层巷道中Hx分量信号的场强值衰减与传播距离呈现近似线性关系,为无线电波反射成像算法奠定理论基础。其次,在模型中距巷道5、10、15、20、25、30 m处设置断层异常区。与正常无断层煤层相比:Hx分量场强值在断层处会发生数值突变,场强值先增大再减小,并且随着断层距巷道距离的增大反射场强值整体减小;当断层距巷道25 m以后,场强值变化不明显。最后,利用某煤矿工作面进行现场试验。试验采用0.965 MHz的频率进行整条巷道的无线电波反射探测,探测结果中地质异常附近无线电波场强值异常升高,显示出明显的直达波和反射波相叠加的现象。通过回采揭露验证,场值异常处与断层位置吻合较好,试验取得良好的效果。综上所述,无线电波在正常煤层巷道中场强值衰减与传播距离呈近似线性关系,当工作面内存在构造异常时会产生直达波和反射波相叠加的现象,其场值会发生跳跃升高。采用反射无线电波法进行煤层工作面地质异常探测具有可行性和有效性,为煤层工作面地质构造探查提供一种新的方法和思路。

Mine radio wave exploration can be used for coal seam geological structure exploration.With its advantages of portability and good effect,it has become a conventional and necessary means for coal seam geological structure exploration.At present,the energy attenuation of radio wave signal in coal seam is fast,and the transmission radio wave detection of working face is restricted in large width coal seam.On this basis,the radio wave reflection exploration method of coal seam working face is proposed.Firstly,the electric model of two-dimensional coal measure strata is constructed by numerical simulation to analyze the field strength value of radio wave Hx component signal.The experimental results show that the attenuation of the Hx component signal in the normal coal seam roadway is approximately linear with the propagation distance,which lays a theoretical foundation for the radio wave reflection imaging algorithm.Secondly,fault anomaly areas are set at 5,10,15,20,25 and 30 m away from roadway in the model.Compared with the normal coal seam,the Hx component field strength value has a mutation at the fault.The field strength value increases first and then decreases,and the over all reflected field strength value decreases with the increase of the distance between the fault and the roadway.When the fault is 25 m away from the roadway,the field strength value change is not obvious.Finally,the field experiment was carried out in a coal mine working face.The experiment uses the frequency of 0.965 MHz to detect the radio wave reflection of the whole roadway.In the detection results,the field strength value of radio wave near the geological anomaly is abnormally high,showing an obvious superposition of direct wave and reflection wave.The abnormal field value agrees well with the fault position from the actual mining verification data,and the experiment has achieved good results.In summary,the attenuation of field strength value of radio wave in normal coal seam roadway is approximately linear with the propagation distance.When there is any geological structural anomaly in the working face,the superposition of direct wave and reflected wave will occur,and the field value will jump up.It is feasible and effective to detect geological anomalies by reflection radio wave method,which provides a new method and idea for geological structure exploration in coal seam working face.