本文選題：航空瞬變電磁法　切入點(diǎn)：電導(dǎo)率深度成像　出處：《成都理工大學(xué)》2015年碩士論文

【摘要】：由于航空瞬變電磁法具有成本較低、勘探效率高、可大面積勘查等優(yōu)點(diǎn),所以該方法已經(jīng)在礦產(chǎn)資源勘查、地下水調(diào)查、地質(zhì)填圖和環(huán)境監(jiān)測等領(lǐng)域獲得了廣泛的應(yīng)用。盡管航空瞬變電磁反演已經(jīng)獲得了大量研究,但是由于航空瞬變電磁數(shù)據(jù)量較大、反演耗時(shí)較高,所以反演解釋已經(jīng)阻礙了該方法的推廣。為此,作為一種快速成像方法,電導(dǎo)率深度成像(CDI)方法已經(jīng)成為航空瞬變電磁法實(shí)用化的關(guān)鍵技術(shù)之一。本文分別對(duì)基于查詢表和基于水平薄板模型的CDI方法進(jìn)行研究并編程實(shí)現(xiàn),同時(shí)分析這些方法的特點(diǎn)。具體來說,主要研究內(nèi)容如下:(1)航空瞬變電磁一維正演方法。首先,通過麥克斯韋方程組得到擴(kuò)散方程,并推導(dǎo)出中心回線航空瞬變電磁的一維正演模擬公式;然后,運(yùn)用G-S變換和漢克爾積分變換對(duì)正演公式進(jìn)行計(jì)算,其中G-S變換采用12個(gè)系數(shù),漢克爾積分變換采用120個(gè)的零階濾波系數(shù)和140個(gè)的一階濾波系數(shù)。上述的正演計(jì)算公式為后續(xù)的查詢表的建立奠定了理論基礎(chǔ)。(2)基于一維正演查詢表的電導(dǎo)率深度成像方法。首先,分別建立假層均勻半空間查詢表和時(shí)間序列?(?)查詢表;然后,通過三次樣條插值法對(duì)查詢表進(jìn)行插值并根據(jù)待成像的電磁響應(yīng)值實(shí)現(xiàn)電導(dǎo)率查詢;最后,分別采用不同的視深度計(jì)算公式得到視深度,從而獲得電導(dǎo)率深度成像結(jié)果。同時(shí),分析了上述兩種查詢表方法在一維、準(zhǔn)二維地電模型中的成像結(jié)果。(3)基于水平薄板模型電導(dǎo)率深度成像方法。首先,分析研究了水平薄板模型電磁正演響應(yīng),并通過正演響應(yīng)公式進(jìn)行了基于水平薄板模型電導(dǎo)率深度成像方法原理推導(dǎo);然后,采用Maxwell軟件的2.5維航空瞬變電磁正演程序獲得電磁模擬數(shù)據(jù);最后,對(duì)電磁模擬數(shù)據(jù)進(jìn)行成像并對(duì)成像結(jié)果進(jìn)行分析。(4)實(shí)測航空瞬變電磁數(shù)據(jù)的成像結(jié)果與分析。首先,利用本研究組所研制的吊艙式直升機(jī)時(shí)間域航空電磁數(shù)據(jù)處理及解釋軟件系統(tǒng)對(duì)實(shí)測數(shù)據(jù)進(jìn)行預(yù)處理,獲得航空瞬變電磁剖面數(shù)據(jù);然后,分別使用基于假層均勻半空間的CDI方法和基于水平薄板模型的CDI方法對(duì)實(shí)測的電磁剖面數(shù)據(jù)進(jìn)行成像;最后,對(duì)成像結(jié)果進(jìn)行分析,驗(yàn)證上述成像方法的有效性和正確性。
[Abstract]:Because the aeronautical transient electromagnetic method has the advantages of low cost, high exploration efficiency and large area exploration, it has been widely used in mineral resources exploration, groundwater survey, geological mapping and environmental monitoring.Although a great deal of research has been done on aeronautical transient electromagnetic inversion, because of the large amount of aeronautical transient electromagnetic data and the high time consuming of the inversion, the inversion interpretation has hindered the popularization of this method.Therefore, as a rapid imaging method, the conductivity depth imaging (CDI) method has become one of the key technologies in the application of aeronautical transient electromagnetic method.In this paper, CDI methods based on query table and horizontal thin plate model are studied and implemented, and the characteristics of these methods are analyzed.Specifically, the main research contents are as follows: 1) one-dimensional forward modeling method of aeronautical transient electromagnetic.First, the diffusion equation is obtained by Maxwell's equations, and the one-dimensional forward simulation formula of aeronautical transient electromagnetic in the central loop is derived, and then the forward formula is calculated by using G-S transform and Hankel integral transform.Among them, G-S transform uses 12 coefficients, Hankel integral transform uses 120 zero-order filter coefficients and 140 first-order filtering coefficients.The above forward calculation formula lays a theoretical foundation for the subsequent establishment of the look-up table. (2) the conductivity depth imaging method based on the one-dimensional forward lookup table.Firstly, a pseudo-layer uniform half-space query table and a time series are established respectively.The look-up table is then interpolated by cubic spline interpolation method and the electrical conductivity query is realized according to the electromagnetic response value of the imaging. Finally, the apparent depth is obtained by using different formulas for calculating the apparent depth.The results of electrical conductivity depth imaging are obtained.At the same time, the imaging results of the above two look-up table methods in one-dimensional and quasi-two-dimensional geoelectric models are analyzed. The results are based on the conductivity depth imaging method of the horizontal thin plate model.Firstly, the electromagnetic forward response of horizontal thin plate model is analyzed and studied, and the principle of conductivity depth imaging method based on horizontal thin plate model is deduced by forward response formula.The electromagnetic simulation data are obtained by the 2.5-D aeronautical transient electromagnetic forward modeling program of Maxwell software. Finally, the electromagnetic simulation data are imaged and the imaging results are analyzed. 4) the imaging results and analysis of the measured aeronautical transient electromagnetic data are analyzed.Firstly, the time-domain aero-electromagnetic data processing and interpretation software system of the podded helicopter developed by this research group is used to preprocess the measured data to obtain the aeronautical transient electromagnetic profile data.The CDI method based on pseudo-layer uniform half-space and the CDI method based on horizontal thin plate model are used to image the measured electromagnetic profile data respectively. Finally, the imaging results are analyzed to verify the validity and correctness of the above imaging methods.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P631.326

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