基于广域电磁法的巨厚型基岩滑坡导水断裂探测研究

来源期刊:中南大学学报(自然科学版)2021年第5期

论文作者:宋国壮 张玉芳 李帝铨 张乔勋

文章页码:1532 - 1542

关键词:广域电磁法;基岩滑坡;地下水;断裂构造;富水地层

Key words:wide-field electromagnetic method; bedrock landslide; underground water; fault structure; water-rich stratum

摘    要:针对巨厚型基岩滑坡形成机制复杂、地下水及断裂构造埋藏深等特点,采用广域电磁法和拟流场法开展不同深度地下水及断裂构造的三维立体探测研究,并结合钻探、挖探等勘探手段对解译结果进行验证。研究结果表明,广域电磁法L3,L11及L15测线识别出3处浅部低阻富水区,其分布范围与拟流场法解译结果基本一致,其中Y-1富水区包络的BZ-7和BZ-8钻孔揭露承压水;距地表500~2 200 m深度内揭示深部低阻富水地层,推测地层为中元古代富水变质岩系。古近纪西宁组地层内识别2处电性突变异常带,分别与地质探洞、横洞挖探揭露的F-1和F-2南倾逆断层位置、产状特征高度吻合,均沿北西-南东走向展布并横穿滑坡体,推测F-1逆断层阻隔了深部地下水向河侧运移,F-1和F-2逆断层共同作用为降雨和深部地下水向主滑段多层滑带渗流补给提供了导水通道。

Abstract: Aiming at the engineering geological characteristics of the huge thick bedrock landslide, wide-field electromagnetic method and flow field fitting method were used on exploring the underground water and fault structure at different depths, and the interpretation results were verified by drilling and excavation prospecting. The results show that three low-resistivity rich water areas in the shallow are identified by wide-field electromagnetic method, and their distribution range and depth are basically identical with the interpretation conclusions of flow field fitting method, in which the boreholes of BZ-7 and BZ-8 in Y-1 rich-water area reveal confined water; in addition, the strata of low-resistivity water-rich area in the deep are presumed to be mesoproterozoic metamorphic rocks. Two electrical mutation anomaly zones which spread along the northeast-southwest trend and across the landslide are identified in the Palaeogene Xining group, and their positions and occurrences are highly consistent with F-1 and F-2 south poured reverse fault in excavation prospecting cave. It is conjectured that the F-1 reverse fault blocks the migration of deep groundwater to the river side, and the interaction of F-1 and F-2 reverse fault provides the channel for the seeping of rainfall and deep groundwater to the multilayer sliding zone of main sliding section.

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