Research on 3D Water Content Inversion of Underground Magnetic Resonance Sounding for Advanced Detection in the Tunnel

摘要

Magnetic Resonance Sounding (MRS) is a relatively new geophysical method for directly detecting the location and water content of water-bearing structure in front of the tunnel.In this paper,we build three-dimensional meshes in front of the tunnel based on the tetrahedral cell,which is much smaller than the hexahedral cube.Then with the MRS forward formulae,we calculate the3D MRS kernel by Hammer Integration,which has a high integral accuracy in a tetrahedral cell.3D inversion with initial amplitude is brought up,which uses Gauss-Newtown method and linear search for iteration.Method for determination of regularization parameters is put forward as well.We simulate the MRS signals of a water-bearing fault and cave in front of the tunnel,and use 3D IVI method to estimate the location and water content.The inversion results show that MRS is effective and accurate in detecting water-bearing structure.