Transient electromagnetic tunnel advanced prediction method under tunnel boring machine construction condition

Abstract

The invention discloses a transient electromagnetic tunnel advanced prediction method under a tunnel boring machine construction condition. The method comprises the following steps of firstly, subtracting TBM machine theory response from an acquisition signal, removing a part of TBM response, and through a mathematical transformation relation and corresponding signal processing, converting a transient electromagnetic diffusion field signal into a virtual wave field signal satisfying an independent component analysis requirement; secondly, using an information independent component analysis algorithm to carry out TBM interference separation and extracting an tunnel transient electromagnetic geological characteristic signal; and finally, using Born approximate inversion to realize underground medium virtual wave field inversion imaging, combining a global apparent resistivity definition to realize the interpretation of a geologic anomaly in front of a tunnel face, and completing the transient electromagnetic advanced geological prediction of a TBM excavation tunnel. In the invention, low-resistance geological anomaly information in front of the face can be effectively extracted, TBMmachine interference is suppressed, and the key problem of the advanced prediction of a transient electromagnetic method in a TBM construction tunnel is effectively solved.

Description

technical field [0001] The invention belongs to the field of geophysical detection, in particular to a transient electromagnetic tunnel advance prediction method under the construction condition of a tunnel boring machine. Background technique [0002] Tunnels and underground projects in western my country have the characteristics of "large buried depth, long tunnel line, complex geology, and steep terrain". Full-face tunnel boring machines (Tunnel Boring Machines, TBMs) are mainly used for excavation. However, in TBM construction tunnels, due to the serious electromagnetic response interference of large metal equipment, the application of transient electromagnetic method in advance prediction in TBM construction tunnels has encountered great difficulties. How to effectively extract the low-resistance geological anomaly information in front of the tunnel face and suppress the interference of the TBM machine has become a key issue for whether the advanced prediction of the tr...

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Problems solved by technology

[0003] Because the electromagnetic response of the TBM machine is strong, and it overlaps with the response of the underground medium in time and frequency, it is difficult for the traditional denoising method to achieve good results.

In the aspect of transient electromagnetic TBM interference elimination, the researchers tried to calculate the total response containing TBM and underground anomaly, the pure anomaly response without TBM influence, and the pure TBM response based on the FDTD forward modeling method. The response of the TBM is directly subtracted from the total response), and the response of the pure underground anomaly is obtained. Based on the numerical simulation method to eliminate the TBM interference, a good effect has been achieved in the realization of the theoretical model, but this method relies on the accurate modeling of the TBM , directly subtracting the theoretical TBM response that is inconsistent with the actual situation, it is easy to introduce new anomalies or cover up the real geological disasters, resulting in wrong predictions, and the actual application effect is restricted

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