Double-couple source ground-well transient electromagnetic detection method

Abstract

The invention relates to a double-couple source ground-well transient electromagnetic detection method, which includes the following steps: a grounding lead is placed in a ground area corresponding toa roadway to be detected which is located underground as a double-electric dipole emission source used for generating an electromagnetic field; at a top plate, a bottom plate and / or a lateral wall ofthe roadway to be detected, receiving devices are arranged along the roadway direction, and the receiving devices include single or a plurality of receiving probes, and can collect electromagnetic signals received by each of the receiving probes; bipolar pulse current is applied to the double-electric dipole emission source to excite an electromagnetic field; an underground medium is subjected toinduction of the electromagnetic field to generate an induction electromagnetic field, and the underground medium includes ground or a detection target layer / body; each of the receiving probes measures the induction electromagnetic field to obtain characteristics of the induction electromagnetic field which change with time; by analysis of the characteristics changing with time, electrical characteristics of the underground medium are extracted; and according to the electrical characteristics, the spatial distribution and extending direction of the underground medium are judged.

Description

technical field [0001] The invention belongs to the technical field of geological detection of coal mining working faces in coal mines, and relates to a ground-underground multi-source transient electromagnetic detection method for water-bearing and water-conducting geological structures affecting safe production on the top plate, bottom plate, inside of the working face and the tunneling head. Background technique [0002] There are many methods for geological detection of coal mining face in coal mines. The common ones are mine direct current method, mine transient electromagnetic method, radio wave tunnel perspective method, magnetic source ground-roadway transient electromagnetic detection method, etc. [0003] Mine direct current method is mainly used for roadway floor sounding and the water-bearing structure in front of the head, which can solve the problem of layer division and water-rich body delineation (that is, direct current sounding and advanced detection). The ...

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Problems solved by technology

However, this technology still has the following problems: the set target is often placed in front of the detection, and the influence of the medium beyond the detection interface, especially the rear, is not ruled out; The interpretation theory needs to be perfected; the detection anomaly area is much larger than the actual geological anomaly body, and the interpretation method needs to be improved; the underground launcher is affected by the space of the underground roadway, so it cannot be made larger, because the emission magnetic moment cannot be large enough, seriously Affected the detection depth and accuracy, etc.

The disadvantages of this technology are: higher requirements on the working environment, such as no electrical equipment emitting electromagnetic waves around the working face, cable lines are required to be disconnected, and cannot be charged; Geological bodies with high conductivity have a strong ability to absorb electromagnetic waves. If there is a good conductor on the way of radio wave propagation, electromagnetic waves will be absorbed quickly, and the signal received in the receiver is very weak, or it cannot be received at all. And the so-called "shadow"

But at present, the specific implementation of this technology still has the following deficiencies: it is impossible to detect the potential water inrush hazards inside the working face and in the roof and floor; The distance between ground transmission and roadway reception is relatively long, and the signal strength of the field source may not meet the detection requirements of large depths

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