【摘要】：近年來，瞬變電磁測深法（Transient Electromagnetic Method）在實際工程地質(zhì)勘探中得到廣泛的應(yīng)用。它是一種時間域電磁勘探方法，利用階躍波或其它脈沖電流場源激勵，在大地產(chǎn)生過渡過程場，斷電瞬間在大地中形成渦旋交變電磁場，測量這種由地下介質(zhì)產(chǎn)生的二次感應(yīng)電磁場隨時間變化的衰減特性，從測量得到的異常信號中分析出地下介質(zhì)體的導(dǎo)電性能和位置，從而達到解決地質(zhì)問題的目的。并且隨著將地震學(xué)中一些已成熟的方法和技術(shù)應(yīng)用到瞬變電磁測深方法中，人們越來越關(guān)注從波場的角度，把瞬變電磁場轉(zhuǎn)換為人們所熟悉的波動場以獲取更多、更準(zhǔn)確的地下地質(zhì)體信息。然而以往都是將磁性源或電性源看做偶極子，通過比擬得到諧變場的頻域表達式，再經(jīng)頻域到時域的變換得到時域解析公式。 本文以時變點電荷假設(shè)代替偶極子假設(shè)，直接在時間域求解瞬變電磁場解析式。首先總結(jié)回顧了全空間有源波動場的時域Green函數(shù)解，并運用分離變量方法推導(dǎo)出全空間齊次阻尼波動方程的直接時域解析式。 其次，在全空間直接時域解析式的基礎(chǔ)上，采用分離變量法給出均勻半空間齊次阻尼波動方程的時域解析式，通過有源Maxwell方程對應(yīng)的電磁場矢量方程，推導(dǎo)出上半空間一次有源波動場和反射波（無源二次波動場）時域解析式，進而給出了均勻半空間瞬變電磁場直接時域解析式。 然后，在均勻半空間直接時域解析式的基礎(chǔ)上，利用邊界條件，推導(dǎo)出線性、均勻水平層狀介質(zhì)中的瞬變電磁場直接時域響應(yīng)式。 這種在時間域內(nèi)嚴(yán)格推導(dǎo)瞬變電磁場響應(yīng)式的方法，避免了傳統(tǒng)引入位函數(shù)以及偶極子假設(shè)所帶來的誤差，并為從事地質(zhì)勘探的工作者和瞬變電磁探測理論的改進提供新的理論依據(jù)。 最后，，采用連續(xù)正則化方法求解波場變換反演問題。構(gòu)造展平泛函，基于已經(jīng)正則化的變分問題用差分法作有限維逼近。利用偏差原理和Newton三階迭代收斂格式選出最優(yōu)的正則化參數(shù)，實施數(shù)值求解。通過對數(shù)值計算結(jié)果和已知的波場函數(shù)之間的比較，證明了該方法的有效性和可行性。與離散正則化算法相比，這種連續(xù)正則化算法具有保結(jié)構(gòu)和收斂速度快等優(yōu)點。
[Abstract]:In recent years, transient electromagnetic sounding (Transient Electromagnetic Method) has been widely used in practical engineering geological exploration. It is a kind of time domain electromagnetic exploration method, which uses step wave or other pulse current field source to generate transition process field in the earth, and produces vortex alternating electromagnetic field in the earth at the moment of loss of electricity. The attenuation characteristics of the secondary induction electromagnetic field produced by the underground medium with time are measured, and the electrical conductivity and position of the underground dielectric body are analyzed from the abnormal signals obtained from the measurement, so as to achieve the purpose of solving the geological problems. And with the application of some mature methods and techniques in seismology to transient electromagnetic sounding methods, people pay more and more attention to converting transient electromagnetic fields into familiar wave fields from the angle of wave field in order to obtain more. More accurate underground geological information. However, in the past, magnetic or electrical sources were regarded as dipoles. The frequency domain expressions of the harmonic field were obtained by analogy, and then the time domain analytical formulas were obtained by the transformation from frequency domain to time domain. In this paper, the time-varying point charge hypothesis is used to replace the dipole hypothesis, and the analytical expression of transient electromagnetic field is solved directly in the time domain. Firstly, the time-domain Green function solutions of the full-space active wave field are reviewed, and the direct time-domain analytical formula of the full-space homogeneous damping wave equation is derived by using the method of separating variables. Secondly, on the basis of the full-space direct time-domain analytic formula, the time-domain analytic expression of homogeneous damping wave equation in half-space is given by using the separated variable method, and the electromagnetic field vector equation corresponding to the active Maxwell equation is obtained. The time domain analytical expressions of primary active wave field and reflected wave (passive quadratic wave field) in upper half space are derived, and then the direct time domain analytical expressions of transient electromagnetic field in uniform half space are given. Then, on the basis of the direct time-domain analytical formula in uniform half-space, the direct time-domain response of transient electromagnetic field in linear and uniform horizontal layered media is derived by using the boundary conditions. This method of strictly deducing the transient electromagnetic field response in the time domain avoids the errors caused by the traditional introduction of the potential function and the dipole hypothesis. It also provides a new theoretical basis for the workers engaged in geological exploration and the improvement of the theory of transient electromagnetic detection. Finally, the continuous regularization method is used to solve the inversion problem of wave field transformation. The flattened functional is constructed and the finite-dimensional approximation is made by the finite difference method based on the regularized variational problem. The optimal regularization parameters are selected by using the deviation principle and the Newton third-order iterative convergence scheme, and the numerical solution is carried out. The effectiveness and feasibility of the proposed method are proved by comparing the numerical results with the known wave field functions. Compared with the discrete regularization algorithm, the continuous regularization algorithm has the advantages of structure-preserving and fast convergence.
【學(xué)位授予單位】：遼寧工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：O441.4

【參考文獻】

中國期刊全文數(shù)據(jù)庫 前10條

1 張保祥,劉春華;瞬變電磁法在地下水勘查中的應(yīng)用綜述[J];地球物理學(xué)進展;2004年03期

2 趙國澤;陳小斌;湯吉;;中國地球電磁法新進展和發(fā)展趨勢[J];地球物理學(xué)進展;2007年04期

3 薛國強;李貅;底青云;;瞬變電磁法理論與應(yīng)用研究進展[J];地球物理學(xué)進展;2007年04期

4 薛國強;李貅;底青云;;瞬變電磁法正反演問題研究進展[J];地球物理學(xué)進展;2008年04期

5 馮國峰,韓波,劉家琦;二維波動方程約束反演的大范圍收斂廣義脈沖譜方法[J];地球物理學(xué)報;2003年02期

6 白登海,Maxwell A Meju,盧健,王立鳳,何兆海;時間域瞬變電磁法中心方式全程視電阻率的數(shù)值計算[J];地球物理學(xué)報;2003年05期

7 李貅;薛國強;宋建平;郭文波;武軍杰;;從瞬變電磁場到波場的優(yōu)化算法[J];地球物理學(xué)報;2005年05期

8 李貅;戚志鵬;薛國強;范濤;朱宏偉;;瞬變電磁虛擬波場的三維曲面延拓成像[J];地球物理學(xué)報;2010年12期

9 楊文采，杜劍淵;層析成像新算法及其在工程檢測上的應(yīng)用[J];地球物理學(xué)報;1994年02期

10 牛之璉;瞬變電磁測深法對導(dǎo)電層的探測能力[J];地質(zhì)與勘探;1992年07期

本文編號：2466202