CAJ | 학술논문

为了研究探测3D导电岩脉状目标体的可控源音频电磁法(CSAMT)的最佳观测装置,我们用压缩积分方程法数值模拟了赋存于导电薄层下的3D导电岩脉的电磁场响应.计算结果表明,最有效的源的位置是把发射源沿岩脉的走向放置.相对于其他几种装置,这种观测装置得到的异常场与主场的比值最大.利用这种最佳的观测装置,通过将异常场E_(ya)和H_xa与噪音作对比,研究了当岩脉的埋深和高度发生变化时岩脉的可探测性问题.当岩脉的顶部埋深增加时,导电岩脉的可探测性降低.岩脉高度的变化对异常场幅值的影响要小于岩脉顶部埋深所产生的影响.所以通常情况下,即便应用了最有效的CSAMT装置,也很难探测到岩脉的高度,应用钻孔中的探测可能会解决这个问题.
위료연구탐측3D도전암맥상목표체적가공원음빈전자법(CSAMT)적최가관측장치,아문용압축적분방정법수치모의료부존우도전박층하적3D도전암맥적전자장향응.계산결과표명,최유효적원적위치시파발사원연암맥적주향방치.상대우기타궤충장치,저충관측장치득도적이상장여주장적비치최대.이용저충최가적관측장치,통과장이상장E_(ya)화H_xa여조음작대비,연구료당암맥적매심화고도발생변화시암맥적가탐측성문제.당암맥적정부매심증가시,도전암맥적가탐측성강저.암맥고도적변화대이상장폭치적영향요소우암맥정부매심소산생적영향.소이통상정황하,즉편응용료최유효적CSAMT장치,야흔난탐측도암맥적고도,응용찬공중적탐측가능회해결저개문제.
Three-dimensional (3D) electromagnetic (EM) fields of a conductive dyke with a conductive overburden are simulated numerically using 3D contraction integral equation (CIE) method to discuss the optimal survey configuration of the controlled-source audio-frequency magnetotelluric (CSAMT) method in order for the exploration of conductive dyke-type target.The calculation results show that the most effective configuration of the transmitter is the case that the direction of the grounded-wire transmitter is along the strike of dyke. In this configuration, the ratio of anomalous fields to primary fields becomes larger than those of any other survey configurations.Using the optimal survey configuration, we also investigate the detectability of the conductive dyke. We calculate the anomalous fields E_(ya) and H_(xa), which are the responses of the conductive dyke only, and compare them to the noise level for the cases that the depth and the height of the conductive dyke are variable. When the depth of top of the dyke increases, the detectability of the conductive dyke decreases. Also, the effect of the height of the dyke to the amplitude of the anomalous fields is much smaller than that of the depth, so that it is usually difficult to detect the height of the dyke by general CSAMT measurement even with the optimal survey configuration. The measurement using borehole can be helpful to address this problem.