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AMT数据地形畸变影响与带地形反演效果研究 被引量:3

A research on the effect of topographic distortion on AMT and the result of its inversion with terrain
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摘要 在山区进行音频大地电磁测深(AMT)时,电磁场易受地形起伏影响发生畸变。为研究起伏地形对AMT数据的影响,采用WinGlink软件基于有限差分算法的正演模块,建立二维起伏地形和平地地电模型,并对比分析了两个理论模型的正演响应。结果表明:TE模式的视电阻率曲线在高频段受干扰程度相对较大,在低频段影响减小甚至消失;TM模式的视电阻曲线变化正好相反;二者相位受地形影响则较小。对含异常体的带地形地电模型进行正演计算,在正演响应中加入2.5%的随机误差模拟实测数据,利用WinGlink软件基于非线性共轭梯度(NLCG)算法的反演模块,分别进行带地形和不带地形的TE、TM和TE+TM模式的二维反演。各反演结果的对比表明,带地形的二维反演结果明显优于不带地形的反演结果,能够较好地反映出异常体的位置、形态及电阻率值。依据得到的认识,对青海祁连隧道工程的AMT实测数据进行带地形二维反演,取得了理想的应用效果。 The electromagnetic field distortion easily affected by the steep topography,especially applying the audio magne-totelluric sounding( AMT)in the mountainous areas. In order to study the influence of rough terrain on AMT data, using theWinGlink software based on finite difference method of forward module to establish the 2D rough terrain and flat of geoelectricmodel,and comparatively analyze the two theoretical models of forward response. The results show that the disturbance degreeof apparent resistivity curve of TE mode is relatively strong in the high frequency band,less of an effect in low frequency bandand even disappeared,and the change of apparent resistance curve of TM mode is just opposite. The both phas affected by theterrain are very small. WinGlink software, which is based on the inversion module of nonlinear conjugate gradient(NLCG)meth-od,is applied to carry out 2D inversion of TE,TM and TE+TM mode with the terrain and without terrain for anomalous geoe-lectric model with topography of forward response,the forward response add 2. 5% of the random error to simulate the meas-ured data. By comparing the inversion results, the 2D inversion results with topography are better than the inversion resultswithout topography, which can well reflect the location,shape and resistivity of the abnormal body. Finally,according to the un-derstanding, the 2D inversion method with terrain is used to invert AMT measured data of tunnel project in Qilian, Qinghai, and has been achieved ideal application effect.
出处 《物探化探计算技术》 CAS CSCD 2017年第3期319-326,共8页 Computing Techniques For Geophysical and Geochemical Exploration
基金 国家高技术研究发展计划(863)(2014AA06A603)
关键词 音频大地电磁测深 带地形反演 TE模式 TM模式 WinGlink audio magnetotelluric sounding inversion with terrain TE mode TM mode WinGLink
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