可控音频电磁法在野三关隧道岩溶及断裂发育带勘察中的应用

Application of Controllable Audio Electromagnetic Method to Cavern Tunnels and Faults of Yesanguan

将可控音频电磁法（CSAMT）应用于宜（昌）万（州）铁路隧道路肩线所经过的基岩内的岩溶及断裂发育带。采用发射源的偶极距离为2.6km,发射机与接收机之间距离大于9km,所发射的频率为2^0-2^13Hz的14个基频以及11个谐频,接收沿测线方向的电场和垂直测线方向的磁场,采用带地形的2D平滑模型稳健的反演迭代算法获得电阻率剖面,结合工程钻探及地质资料,较为准确地推断出了隧道路肩线附近的岩溶、断裂发育带分布。

This paper presents a successful application of the Controlled Source Audiofrequency Magnetotelluric method（CSAMT） to investigate geological hazard bodies in bedrock near the shoulder line of a tunnel along Yiwan railway.In this study,a transmitter source dipole spacing of 2.6 km with a transmitter receiver distance of 9 km was used.Field measurements selected the 14 base frequencies and 11 harmonic frequencies between 2 ^0 - 2^ 13Hz as the reflection frequency.Electric field along the direction of survey line and magnetic field perpendicular to the survey line were measured.Resistivity profiles were constructed using 2D smooth model inversion iterative algorithm.Karst caves,fractured zones and faults near the shoulder line of the tunnel were successfully inferred through interpretation of the CSAMT measurement data combining with borehole data and geological layer information.