回线源瞬变电磁测深快速反演方法

回线源瞬变电磁测深法(简称瞬变电磁法或TEM法)是以不接地回线为场源,在回线内、外测量电磁场的一种电磁测深方法,已经广泛用于固体矿产、工程地质和水文地质调查工作之中[1,2]。目前,回线源瞬变电磁法主要采用中心回线和重叠回线两种测量装置,测量回线内垂直磁场产生的感应电动势。“烟圈”反演方法是瞬变电磁反演的主要计算方法,“烟圈”反演利用地表瞬变电磁响应与某时刻电流源镜像等效原理,计算勘探深度和对应电阻率。这里给出了回线源瞬变电磁测深一维“烟圈”反演解释方法的基本原理、计算方法和应用实例。结果表明,一维“烟圈”反演解释结果纵向分辨率较高,能反映出地下电性变化情况,可以用于瞬变电磁测深资料解释工作。

A rapid inversion technique for loop source transient electromagnetic method

Loop source transient electromagnetic method(for short: transient electromagnetic method or TEM) is one of transient electromagnetic sounding methods which takes the ungrounded rectangular loop-lines as transmitting source and mesured inside and outside the rectangular loops,and has been widely applied in mineral resources,engineering geology and hydrogeology survey at present.Loop source transient electromagnetic method mostly uses central-loop and coincident loop equipments,and measures the voltage induced in a upright magnetic field.In data interpretation,we mostly used smoke ring inversion interpreting method.We compute the depths and the homologous resistivity by smoke ring inversion interpreting method based on equating the response measured at the surface of the earth at each delay time to the magnetic field of images of the source. And this paper describes the basic principles and application instances of 1-D smoke ring inversion interpreting method.Actual application results indicated that the longitudinal resolving power is relatively accurate in 1-D smoke ring inversion interpreting computing and the computing can reflect the electricity changes and be used in the interpreting works for electromagnetic sounding data.