大地电磁测深法探测山区深埋隧道隐伏构造——以安石隧道探测为例

Magnetotelluric Sounding Method for Detecting Concealed Structures of Deep-buried Tunnels in Mountainous Areas:Taking the Detection of Anshi Tunnel as an Example

隧道掌子面前方与上方存在的隐伏构造在隧道施工过程中具有极强的致灾性。针对云南凤庆安石隧道具有长、大、深埋,且其地表起伏大的特点,采用大地电磁测深法对隧道上方隐伏构造进行探测。首先对观测数据进行静态效应校正等预处理;随后进行带地形的基于光滑约束最小二乘反演,得到了隧道轴线及平行轴线的视电阻率剖面图;最后利用反演结果并结合研究区的区域地质构造、岩性特征以及水文地质条件等,揭示出与隧道斜交的两条隐伏构造的空间展布,该成果与后期钻探结果吻合,表明大地电磁测深法可以有效地探测出山区深埋隧道前方与上方隐伏构造的位置与姿态,为隧道安全施工与地质灾害防治提供了重要的参考依据。

The concealed structures in front of and above the tunnel face are highly catastrophic during tunnel construction.Aiming at the characteristics of Yunnan Fengqing Anshi Tunnel,which is long and deeply buried,and its surface is undulating,the magnetotelluric method was used to detect the concealed structure above the tunnel.Firstly,the static effect correction and other pretreatments were carried out for the observation data,then the smooth constrained least squares inversion with terrain was performed to obtain the apparent resistivity profile of the tunnel axis and parallel axis;finally,the spatial distribution of the two concealed structures oblique to the tunnel was revealed by using the inversion results and combining with the regional geological structure,lithologic characteristics and hydrogeological conditions of the study area.Result strongly verify by drilling data,indicating that the magnetotelluric method can effectively detect the position and posture of concealed structures in front of and above deep-buried tunnels in mountainous areas,which provides an important reference for safe construction of tunnels and geological disaster prevention.