| Guizhou Province was a typical karst area-karst,fault,fracture zone and other complex geological distribution was widely distributed,the coal mine water disaster a occurred frequently.It was of significance to study the refinement and quantification of advanced water exploration technology in coal mine heading face to promote safe mining and avoid water disasters.Based on this,this paper taked the 120905 working face of Longfeng Coal Mine as the research object,put forward the comprehensive geophysical prospecting technology of transient electromagnetic and borehole radar,established the electrical experimental system of surrounding rock to explore the response characteristics of electrical excitation under the coupling of coal-rock-water,analyzed the signal attenuation law of electrical parameters under the external magnetic field,summarized the image characteristics of abnormal body combined with field test,put forward a criterion for distinguishing the difference of physical properties of abnormal body,and formulated a set of accurate and feasible transient electromagnetic-borehole radar advanced water detection system.In order to provide guidance for the fine water exploration work in Longfeng area of Guizhou and similar geological conditions.The main research results are as follows :(1)The electrical response characteristics of surrounding rock in working face were clarified.The dielectric constant decreases with the increase of frequency.Due to the continuous electric excitation,the polarization of the medium was bound and the activation was reduced.At 100 MHz,it tended to be stable and the value was quite different.The resistivity decreases with the increase of frequency.The variation curves of the four rock samples were linearly distributed,and the amplitude decreases regularly by about 1-2 times.The difference was significant due to the influence of the external signal,which was used as the division interval of the medium anomaly area.(2)The formation of transient electromagnetic-drilling radar integrated geophysical system.Combed the geological characteristics of the mining area and the risk analysis of water inrush,combined with the electrical response characteristics of the surrounding rock of the working face,the comprehensive geophysical prospecting technology was designed and applied to the 120905 heading face of Longfeng Coal Mine.A total of 6 low-resistance abnormal areas of transient electromagnetic and 8abnormal areas of borehole radar were interpreted.Combined with geological analysis,it was comprehensively determined as water-bearing area,coal-rock layered interface,fracture zone,water-bearing fault and water-bearing fracture.Through drilling verification,it is found that the radar abnormal structure was highly consistent with the transient low resistance area,the location of the abnormal area and the abnormal geology were determined,and the transient electromagnetic-drilling radar comprehensive geophysical prospecting system was formed,indicating that the transient electromagnetic and drilling radar advanced water detection technology had strong applicability,high accuracy and strong reliability.(3)The advanced water exploration mechanism of coal-rock-water coupling occurrence is revealed.Based on the peak difference of surrounding rock characteristics and the attenuation law of capacitance-dissipation coefficient(Cp-D)and impedance signal,combined with the abnormal body image waveform of 120905 working face in field test,a comprehensive geophysical prospecting plan was formed.According to the radar frequency of 100 MHz,the detection depth and accuracy test results are achieved,and the electrical parameter interval of low-resistance abnormal area was further analyzed.Finally,the discriminant basis for distinguishing the abnormal signal in front of the heading face as a water-rich area is obtained,and the advanced water detection mechanism of coal-rock-water coupling occurrence was revealed.The comprehensive detection target of transient electromagnetic to judge the location and scale of water cut and borehole radar to identify the lithology and structure of surrounding rock medium is realized. |
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