磁源边长大小对电磁场扩散速度影响规律研究  

A Study on Diffusion Speed of Electromagnetic Field with Different Size of Magnetic Source

作　　者：于景邨[1] 曾晓波[1] 宋金栋[1] 刘树才[1] 

机构地区：[1]中国矿业大学资源与地球科学学院,徐州221116

出　　处：《地质与勘探》2009年第4期423-426,共4页Geology and Exploration

基　　金：国家重点基础研究发展计划(973计划)项目(编号:2007CB209400)资助

摘　　要：全空间电磁场扩散速度计算的准确性,直接影响矿井瞬变电磁法探测结果的精度。基于电磁场全空间"双烟圈效应"理论,建立了全空间电磁场扩散速度数学模型。对不同边长磁源回线中心电磁场扩散速度进行了对比分析,并对巷道底板三层地电模型全空间理论视电阻率曲线进行了时深转换,结果表明回线边长大,较早时间段回线中心扩散速度大,但衰减速度快,影响浅部地层探测能力;较晚时间段,不同边长磁源回线中心扩散速度趋于相等,说明边长大小对深部地层探测能力影响小。提出了较早时间段电磁场扩散速度校正系数,改进了磁源回线电磁场扩散速度数学模型,为实际探测工作中磁源回线边长大小的选择提供理论依据。The calculation accuracy of diffusion speed in whole -space electromagnetic field affects directly the interpretative precision of TEM survey in underground coal mines. Based on the ＂double smoking rings theory＂ in whole - space electromagnetic field, we established a mathematic model of diffusion speed of electromagnetic field in whole - space. Diffusion speed of electromagnetic field was analyzed and compared with varying side length of mag- netic source loop in whole - space. Converted time - depth of curve of apparent resistivity with 3 seams theory model in laneway floor, the results demonstrate that the diffusion speed of loop center is fast,but decay fast in the early period with long length loop, it＇s weak to survey the shallow layer; in the late period, the diffusion speed with different side length of magnetic source loop tend to be equal, which shows the side length affects depth survey weak- ly. The correction coefficient of diffusion speed with electromagnetic field in the early period was calculated and, the mathematic model of electromagnetic field diffusion speed was ameliorated It might provid theory foundation for choosing magnetic source loop size in practical survey.

关 键 词：全空间 瞬变电磁场 扩散速度 磁源 边长 

分 类 号：P631.325[天文地球—地质矿产勘探]