Solid source transient electromagnetic three-dimensional tunnel advanced forecasting method

Abstract

The invention discloses a solid source transient electromagnetic three-dimensional tunnel advanced forecasting method. The solid source transient electromagnetic three-dimensional tunnel advanced forecasting method comprises steps that transmitting coils are arranged along a whole contour edge of a tunnel face; a plurality of receiving points are disposed on the tunnel face, and a plurality of receiving survey lines, which are parallel to each other, are arranged in a transmitting loop, and then the receiving points are basically spread over the whole tunnel face; the induction electromotive force values of the receiving points are acquired, and the normalization and correction processing of the induction electromotive force values is carried out, and induction electromotive force values measured by adopting an equivalent moving source type transient electromagnetic method are acquired after calculation, and apparent resistivity is calculated; the inversion and the three-dimensional imaging of the acquired apparent resistivity-depth curve data are carried out to realize solid source transient electromagnetic three-dimensional tunnel advanced geological forecasting. The solid source transient electromagnetic three-dimensional tunnel advanced forecasting method is advantageous in that reduction of mutual inductance effect between the transmitting loop and the receiving coil is facilitated, and data quality is improved; the redundant data spread over the whole tunnel face can be also used for the precise three-dimensional imaging, and the three-dimensional advanced forecasting of the tunnel is effectively realized.

Description

technical field [0001] The invention relates to the field of tunnel advanced geological prediction electromagnetic exploration, in particular to a solid-source transient electromagnetic three-dimensional tunnel advanced prediction method. Background technique [0002] With the rapid development of China's transportation network, there are more and more tunnel construction projects. In order to ensure the safety of tunnel construction, the advanced geological prediction of tunnel is a particularly important part in the process of tunnel construction. Transient electromagnetic method is a geophysical electromagnetic prospecting method widely used at present. Its basic principle is: use the ungrounded loop to transmit a step pulse magnetic field underground or in front, and the receiving loop or probe collects the The attenuation data signal of the secondary induced electromagnetic field generated by the eddy current of abnormal geological bodies, and through analysis and inte...

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Problems solved by technology

First of all, since the launch loop must be square and multi-point measurement is required, its detection effect will be severely restricted by the size and shape of the tunnel face, its exploration depth is often small, the amount of data is small, and the detection accuracy is low; secondly, the center loop The position of the receiving point of the line dynamic source transient electromagnetic device is close to the transmitting loop, which makes the mutual inductance effect between the transmitting loop and the receiving loop obvious, and the data quality is relatively poor; finally, the dynamic source transient electromagnetic device It is necessary to constantly move the transmitting loop and receiving loop, which results in low work efficiency

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