杨海燕^1,,
岳建华^2,,,
李锋平²
1. 东华理工大学省部共建核资源与环境国家重点实验室培育基地, 南昌 330013
2. 中国矿业大学资源与地球科学学院, 深部岩土力学与地下工程国家重点实验室, 江苏徐州 221116

基金项目: 国家自然科学基金资助项目（41564001，41674133，41974086）和江西省自然科学基金资助项目（20151BAB203045）联合资助


详细信息

作者简介: 杨海燕, 男, 1980年生, 教授, 博士生导师, 主要从事电磁法勘探理论与应用研究.E-mail:genious_yang@126.com

通讯作者: 岳建华, 男, 1964年生, 教授, 博士生导师, 主要从事煤炭电法勘探与矿井地球物理勘探研究.E-mail:yuejh@cumt.edu.cn

中图分类号: P631

收稿日期:2018-06-05
修回日期:2019-07-08
上线日期:2019-09-05

The decay characteristics of transient electromagnetic fields stimulated by ramp step current in multi-turn small coil

YANG HaiYan^1,,
YUE JianHua^2,,,
LI FengPing²
1. State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China
2. School of Resource and Earth Science, State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Jiangsu Xuzhou 221116, China


More Information

Corresponding author: YUE JianHua,E-mail:yuejh@cumt.edu.cn

MSC: P631

--> Received Date: 05 June 2018
Revised Date: 08 July 2019
Available Online: 05 September 2019


摘要
摘要:采用Duhamel积分对斜阶跃电流激励的瞬变电磁场进行直接计算，应用叠加原理得到了多匝小回线全域瞬变电磁响应.研究了多匝小回线的早、晚延时临界条件以及等磁矩单匝大回线与多匝小回线的延时和关断时间特征，分析了电阻率、厚度等参数变化时斜阶跃电流对层状模型瞬变响应的影响特征，最后采用实测数据验证了关断效应的校正效果.结果显示，回线边长越小或表层电阻率越大，瞬变响应越早离开早期并进入晚期.多匝小回线的关断时间远大于等磁矩的单匝大回线，但由前者激发的瞬变响应进入晚期的时间却大幅提前，更有利于晚期条件下各种理论公式的使用.斜阶跃影响校正结果显示，增加多匝小回线的匝数可以扩展反演深度的范围，减少匝数则可以提高反演电阻率的精确性；实测数据处理结果显示校正方法产生了一定的效果.本研究补充了多匝小回线瞬变电磁理论内容，研究结果可以为复杂环境中小尺寸多匝线圈的工作参数选择提供参考.
关键词: 瞬变电磁法/
斜阶跃电流/
视电阻率/
"烟圈"理论/
互感

Abstract:Applying Duhamel integral and superposition principle, full-time transient electromagnetic response with a ramp current excitation for small multi-turn coils was calculated on a homogeneous half space and a layered medium. The critical conditions of the early and late stages and the decay characteristics during turn-off time for multi-turn small coils were studied in this paper. By varying the resistivity and thickness of the layered medium, the transient response stimulated by ramp current was also analyzed. At the same time, the measured data was adopted to testify the effect on turn-off time correction. The results indicate that, much shorter the loop size is or more higher the near-surface resistivity is, more earlier the transient response leaves the early stage and enters the late stage. Long turn-off time for multi-turn coils compared with single loop, but much earlier critical time entering the late stage, which could be considered as an advantage for using the late-stage formulas. The inversion result after turn-off time correction demonstrates that it has a wide depth range for more turns, while the inverse resistivity is accorded with the model well for less turns. The correction on measured data shows a good effect. The study supplements the theoretical research contents for multi-turn coils TEM, and also provides one option to use small multi-turn coils device at complicated earth surface.
Key words:Transient electromagnetic method/
Ramp current/
Apparent resistivity/
"Smoke ring" theory/
Mutual inductance



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