ISSN 1000-3665 CN 11-2202/P

    综合物探探测豫北灰岩区薄覆盖层隐伏断层方法研究

    Study on the method of comprehensive geophysical prospecting for detecting the thin overburden buried faults in limestone area in northern Henan

    • 摘要: 隐伏断层的精准识别对于水利建设工程至关重要。物探是快速识别隐伏断层的有效方法。由于地球物理问题的多解性,单一物探方法又带有片面性。如何选用优化物探方法组合快速准确识别隐伏断层,是目前亟须解决的难点和热点问题。在综合分析豫北太行山灰岩区各类岩土体物性特征和现场地质条件的基础上,分别对F1小尺度张扭性正断层和F16大尺度扭性平移-正断层开展高密度电法、地震反射波法、折射层析法和瞬态瑞雷面波法等综合物探方法的探测研究工作。研究发现,折射层析法和地震反射波法联合探测成果分别从横波速度和反射波同相轴变化特征完整揭示了F1断层的发育特征。而对于F16断层,高密度电法、地震反射波法和瞬态瑞雷面波法综合探测成果异常区高度吻合,折射层析法也取得一定效果。经钻探和孔内电视验证,F16断层规模庞大,并伴生溶洞,与物探结果吻合。研究结果表明,地震反射波法和折射层析法相结合探测类似F1断层,可有效降低解译成果的多解性,节省探测成本。采用高密度电法普查、地震反射波法和瞬态瑞雷面波法详查,实现了类似F16断层的快速准确识别。两种组合探测技术能够快速确定灰岩区两类典型薄覆盖隐伏断层的位置、深度、产状和性质,有效避免探测工作的盲目性和片面性,为类似工况的高效探测提供了新思路,也将会在该领域发挥更大作用。

       

      Abstract: Accurate identification of the buried faults is crucial for the water conservancy projects construction. Geophysical exploration is an effective method for identifying buried faults quickly. However, due to the multi-solution nature of geophysical problems, a single geophysical method is also one-sided. Therefore, the selection of an optimized combination of geophysical methods to identify buried faults quickly and accurately is currently a difficult and hot issue to be addressed. Based on the comprehensive analysis of the physical characteristics of various rock and soil masses and on-site geological conditions in limestone area of Taihang Mountain in northern Henan, the comprehensive geophysical exploration methods such as electrical resistivity tomography, seismic reflection survey, refraction tomography and transient Rayleigh surface wave method were carried out for the F1 small-scale tensional torsional normal fault and F16 large-scale torsional translational normal fault respectively. It is found that the combined exploration results of refraction tomography and seismic reflection survey fully revealed the development characteristics of F1 fault from the characteristics of shear wave velocity and reflection wave events respectively. For the F16 fault, the comprehensive detection results of electrical resistivity tomography, seismic reflection survey, and transient Rayleigh surface wave method are highly consistent in the abnormal areas, and the refraction tomography has also achieved complete results. F16 fault was verified by drilling and borehole television to be massive and associated with caves, which is consistent with the physical results. The research results show that the combination of seismic reflection survey and refraction tomography for detecting similar F1 fault can reduce the multiplicity of interpretation results and save exploration costs effectively. Using electrical resistivity tomography, seismic reflection survey and transient Rayleigh surface wave method for detailed investigation, rapid and accurate identification of faults similar to F16 has been achieved. The two combined detection techniques can determine the location, depth, occurrence and nature of two types of typical thin overburden buried faults in limestone areas quickly, and could reduce blindness and one-sidedness in the detection work effectively, provide a new idea for efficient detection for similar condition. The proposed method could play a greater role in this field.

       

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