地電法於地下掩埋物調查之研究

A study of detecting the buried object by using geoelectrical methods

林澤宗(Ze-Zong Lin)

指導教授 ： 陳建志

國立中央大學/地球科學學院/地球物理研究所/碩士(2012年)

摘要

直流電阻法廣泛用在地球物理及工程的調查與研究，然而電極排列法的種類繁多，再加上場址特性多元，若要使資料的解釋更精確，則選擇合適的電極排列法在野外工作中尤其重要，當測線周遭存在干擾物，例如地表淺層干擾物、地下掩埋物等，施測的結果就會是測線下方剖面以及周遭(側向)干擾物的混合，資料失真會影響最終的判斷。本研究針對電極排列法的側向效應作研究，以主動(測線平移)及被動(移動人工淺層導體)的方式改變測線與干擾物的距離，並依據移動過程中電阻率剖面的變化情況，討論各種排列法側向效應的大小。試驗一為地下掩埋物試驗，測線起初鄰近掩埋物(槽體)施測，隨後遠離，試驗二為淺層導體移動試驗，淺層導體起初置於測線正上方，隨後逐漸移動遠離測線。若遠離後電阻率剖面相對於遠離前有明顯改變，則代表該排列法資料已經不受干擾物影響，所量測到的是測線下方真實的電性構造資料。
試驗結果顯示，溫奈－施蘭卜吉法的解析度最高，受側向干擾物影響最大。三極和雙極排列法解析度較差，受側向干擾物影響較小。當測線附近無干擾源時，建議以溫奈-施蘭卜吉法量測，因為解析度高，可清楚地探測目標物的邊界及幾何形狀，若測線附近有干擾物時，建議用三極或雙極排列法收取資料，因為此兩種排列法的資料不易受側向干擾物影響，避免資料受干擾而失真，影響最終的結果分析。

關鍵字

側向效應 ； 電阻率影像剖面法 ； 地電 ； 地下掩埋物

並列摘要

The Electrode Resistivity Tomography method was used to many years. In previous studies, they compared many properties between different electrode arrays.In this study, We discuss not only resolution but also lateral effect for different electrode arrays in this study. We chose Edge-Gradient (EG) array, Pole-Dipole (PD) array, Pole-Pole (PP) array and Wenner-Schlumberger (WS) array to do the two tests. In first test, we set survey line near the buried object and then do measuring. After measuring, move survey line leave the buried object 20cm, 40cm, 60cm and 80cm respectively and then do the measuring. Finally, move survey line to 8m measure the background information in first site. In second test, we put artificial shallow conductor upon the survey line and then do measuring. After measuring, move artificial shallow conductor leave the survey line 10cm, 20cm, 30cm and 40cm respectively and then do the measuring. Finally, we remove the artificial shallow conductor to measure the background information in second site. We use resistivity image to discuss the resolution , which survey line near the target in two tests. And then discuss the lateral effect by the variation of resistivity image during moving survey or moving artificial shallow conductor. The result of resolution, Wenner-Schlumberger array and Eege-Gradient array can get better resolution images than Pole-Pole array and Pole-Dipole array. And the lateral effect of Wenner-schlumberger array is strongest in this study

並列關鍵字

lateral effect ； buried object ； Electrical Resistivity Tomography ； Geoelectrical

參考文獻

曹宏志，「應用地電阻影像剖面法於滑動邊坡之研究」，清雲科技大學，碩士論文，民國97年。

楊光程，「二維地電阻影像探測之3D效應研究」，國立交通大學，碩士論文，民國98年。

Chen, P. H., “Imaging the subsurface structure of the North Tip of the 1999 Chi-Chi Earthquake Fault in Central Taiwan Using the Electric resistivity Method”, Terrestrial, Atmospheric and Oceanic Sciences, Vol. 11, 721-734, 2000.

Dahlin, T. and Zhou, B. ,“A numerical comparison of 2D resistivity imaging with 10 electrode arrays”, Geophysical Prospecting, Vol. 52, 379-398, 2004.

Michael van- Schoor, “Detection of sinkholes using 2D electrical resistivity imaging”, Journal of Applied Geophysics, Vol. 50,393– 399, 2002.