Research On 1D Forward And Inversion Interpretation Method Of Transient Electromagnetic Detection Between Ground And Tunnel

Exploring and finding out the hydro-geological conditions of the mine, including faults, karst collapse columns structure and water status, is the problem urgently to be solved of mine hydrogeology. The conventional geophysical exploration methods provide some guidance for preventing water inrush, but which can’t meet the requirements of exploration. In this paper, based on the characteristics of coal mine water inrush, the ground-tunnel TEM is discussed on several respects,such as forward calculation, inverse methods, apparent resistivity formula derivation and field test.Derive the expressions of the underground transient electromagnetic response of large loop source by in homogeneous half space model and layered model, and describes the mathematical calculation method. The computer program was compiled,and achieve the forward numerical simulation of homogeneous half space model and layered model. Discuss the relationship between the transient electromagnetic response of geoelectric parameters and parameters, including circle, current, depth and resistivity.This paper derived and improved the calculation formula of apparent resistivity.receiving point depth is added to the formula. Using the method of kernel function, to solve the apparent resistivity, and experimental results demonstrate the effectiveness of the proposed method. Inversion analysis of ground-tunnel TEM response by using the damped least squares inversion algorithm, and the experimental results verify that this algorithm is feasible and usable.We made a field test of ground-tunnel TEM and compared with the ground Transient electromagnetic method. The results show that is feasible and usable to detect of water and geologic structure. At the same time, it is better than the ground Transient electromagnetic method in detection accuracy and resolution.The successful application of this technology will must rich hydro-geological exploration techniques, but also can improve the technological level of the Mine Water Control, to provide protection for the mine safety production, no doubt having a certain theoretical significance and practical significance.