等值反磁通瞬变电磁法探测滑坡堆积体的应用

Application of opposing-coils transient electromagnetics in the detection of landslide deposits

西部大开发工程基建中经常遇到滑坡体探测问题,由于滑坡体滑床滑动面与第四系覆盖的电性差异小,常规电磁法分辨困难。为此,提出利用等值反磁通瞬变电磁法(OCTEM)探测滑坡堆积体、反向追踪山体错动面的方案,构建滑坡堆积体地电结构模型,通过正演计算研究滑坡堆积体的瞬变电磁响应规律,从理论上分析了不同厚度的滑坡堆积体瞬变电磁响应规律以及在不同覆盖厚度下的瞬变电磁响应规律;对已知滑坡体的探测试验表明滑坡问题上首先分析堆积体观点的正确性,同时表明OCTEM用于山区滑坡堆积体的探测有效性。

The detection of landslide deposits is frequently required in the infrastructure construction of the Western China Development.However,it is difficult to distinguish the landslide deposits using conventional electromagnetic methods because of the small differences in the resistivity between the sliding surface of the sliding bed and the Quaternary overburden.Therefore,this study proposed a scheme that detected the landslide deposits using opposing-coils transient electromagnetics(OCTEM)and then traced the mountain dislocation surface reversely.Accordingly,this study established a geoelectric structure model of the landslide deposits,investigated the transient electromagnetic response patterns of landslide deposits through forward calculation,and theoretically analyzed the transient electromagnetic response patterns of landslide deposits with different thicknesses and those of landslide deposits under different thicknesses of the Quaternary overburden.As verified by the detection results of known landslides,the method proposed in this study is correct and that OCTEM is valid in detecting landslide deposits in mountainous areas.