等值反磁通瞬变电磁法在岩溶塌陷区探测应用

The application of Opposing Coils Transient Electromagnetics in the detection of karst subsidence area

  • 摘要: 由岩溶引发的地面塌陷具有灾害性大,隐蔽性高等特点,为了对其进行有效预报及治理,以某岩溶塌陷强烈发育地区为研究对象,提出采用等值反磁通瞬变电磁法(Opposing Coils Transient Electromagnetics Method,OCTEM)与工程地质钻探相结合的方法,对地层界面进行地球物理方法探测,由覆盖层埋深、电阻率大小、等值线变化等因素确定地层产状,并通过物探反演图及钻孔信息进行验证。结果表明,在岩溶塌陷强烈发育地段,等值反磁通瞬变电磁法可以有效查明地下溶蚀发育情况,在周围环境因素干扰强等常规物探方法无法开展的情况下,可以达到较好的应用效果。等值反磁通瞬变电磁法在岩溶、地面塌陷等地质灾害发育地区提供了有效的预测,为相似情况下的研究分析工作提供理论及实践基础。

     

    Abstract: Ground collapse caused by karst is both disastrous and covert. In order to forecast and control it effectively, a research area with strong karst collapse development was selected in this study, and a method that combines Opposing Coils Transient Electromagnetics with engineering geological drilling was used to verify the formation occurrence through the factors including buried depth of overburden, resistivity and isoline variation. The results of geophysical inversion maps and borehole information verification show that the Opposing Coils Transient Electromagnetics method can effectively identify the development of underground corrosion. Especially in the area where the conventional geophysical exploration methods may easily disturbed by the environmental factors, such method could achieve better application effect. Opposing Coils Transient Electromagnetics achieves effective forecast and prediction results in the developing areas of geological hazards and the karst-induced ground collapse, which could provide some theoretical and practical basis for research and analysis for similar circumstances.

     

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