CAJ | 학술논문

根据瞬变电磁法基本原理，当大定源发射回线下方存在局部不均匀体时，由于不均匀体在接收线圈中产生的二次场方向不同，导致衰减曲线与均匀大地响应曲线偏离。为了分析浅层不均匀体对衰减曲线的影响，采用大定源回线装置发射电流为梯形波，回线面积为150 m×150 m，电流波形为梯形波，幅值为10 A，关断时间为176μs；对于时间常数分别为1、3、5 ms 的浅层不均匀体，利用多匝密绕的闭合线圈（即异常线圈模型）的电磁信号衰减规律，来模拟其响应衰减曲线。研究表明，当异常线圈位于发射回线下方或者是框边下方时，随着发射、异常、接收之间的相对位置的变化，三者之间的互感发生变化，引起异常线圈的响应可能为负值，致使接收到的综合响应衰减曲线出现过0情况。因此，大定源回线结构下存在不均匀体时，产生的负响应值在后续处理时需要引起注意。
근거순변전자법기본원리，당대정원발사회선하방존재국부불균균체시，유우불균균체재접수선권중산생적이차장방향불동，도치쇠감곡선여균균대지향응곡선편리。위료분석천층불균균체대쇠감곡선적영향，채용대정원회선장치발사전류위제형파，회선면적위150 m×150 m，전류파형위제형파，폭치위10 A，관단시간위176μs；대우시간상수분별위1、3、5 ms 적천층불균균체，이용다잡밀요적폐합선권（즉이상선권모형）적전자신호쇠감규률，래모의기향응쇠감곡선。연구표명，당이상선권위우발사회선하방혹자시광변하방시，수착발사、이상、접수지간적상대위치적변화，삼자지간적호감발생변화，인기이상선권적향응가능위부치，치사접수도적종합향응쇠감곡선출현과0정황。인차，대정원회선결구하존재불균균체시，산생적부향응치재후속처리시수요인기주의。
Based on the knowledge of the TEM theory,the secondary field direction generated by the heterogeneities in the position of the receive loop is different when the local heterogeneities exist below large fixed transmit loop,which may result in attenuation curve deviating from the response curve of the homogeneous body.In order to analyze the impact of heterogeneities to the attenuation curve,we adopts large fixed loop equipment whose area is 150 m×150 m and emission current is trapezoidal wave with the amplitude of 10 A and turn-off time of 176 μs.We use the electromagnetic signal attenuation rule of multi-turn and close-wound coil, namely anomaly loop to simulate the response curve of shallow heterogeneities whose time constant is respectively 1 ms,3 ms or 5 ms.When the anomaly loop is located below the transmit loop or its frame edge,with the different relative position between the transmit loop, anomaly loop and receive loop,that will change the mutual inductance of them and cause the response of the anomaly loop negatively and lead to the integrated response attenuation curve of the receive loop appearing zero-crossing condition.So we need to attract attention of the negative response in the subsequent processing when the heterogeneities exist below the large fixed loop.