音频大地电磁在铁路隧道工程勘察中的应用

Application of Audio Magnetotelluric in Geological Engineering Exploration of Railway Tunnel

对于长大深埋铁路隧道的工程地质勘察,音频大地电磁(AMT)已经成为目前最为行之有效的物探勘察手段之一。音频大地电磁(AMT)测深法利用天然电磁场信号为场源,观测天然电磁场的时间序列信号,然后将时间序列数据转化为频率域数据,进而计算出每个频点的电阻率值和相位阻抗。野外采集的时间序列原始数据,经过Robust处理和带地形的二维反演,能真实反应地下的地质信息。通过近几年在青海某铁路隧道等工程的应用,取得了较好的效果。

In the engineering geological investigation, Audio Magnetotelluric （AMT） has become the most effective geophysical means to prospect the long and huge railway tunnel buried deeply. Audio Magnetotelluric （AMT） is using natural electromagnetic field signal as source of the field, observing the time series signal of the natural electromagnetic field. Then it converts the time - series into frequency domain and calculates the resistivity and phases impedance for each frequency. After Robust processing and two - dimensional terrain constrained inversion, the field collection can reflect the true response to the under-ground geology. In recent years, good results have been achieved in application of AMT in some railway tunnels in Qinghai.