Magnetic source ground-tunnel transient electromagnetic advanced detection method

Abstract

A magnetic source ground-tunnel transient electromagnetic advanced detection method can be applied to underground coal mining. Steps of the method are as follows: a coordinate and a dimension of a large loop coil trasnmitted by a magnetic source are determined, and the large loop coil is laid on the ground of a to-be-detected area; quartz clock synchronization is performed on a transmitting machine and a receiving machine; a plurality of receiving probes are arranged in a tunnel until tunnel detection ends; a step current is supplied to a transmitting coil, a secondary eddy current field is inducted under the ground, and the receiving probes receive a signal of the secondary field; the above steps are repeated, receiving probes are arranged along the tunnel according to the same distance, and each receiving probe increases, all the receiving probes perform detection once again until tunneling is completed; and data detected by the receiving probes are made into related drawings, an abnormal response area is obtained through a comparison with preset information, and a front water inrush range is determined. The method has the advantages of high construction efficiency and high expandability, the method adopts large loop emission observation and has best coupling with a detection target, and the method also has the advantages of high detection performance and a high resolution capability.

Description

technical field [0001] The invention relates to an advanced detection method, and is especially suitable for a magnetic source ground-roadway transient electromagnetic advanced detection method used in underground safe coal mining. Background technique [0002] Water inrush disasters in coal mines seriously threaten the safe production of coal mines and bring extremely bad political influence and property losses to the country and society. For this reason, the National Coal Mine Safety Supervision Bureau put forward the sixteen-character principle of "forecasting and forecasting for coal mine water disasters, if in doubt, explore first, explore before digging, treat first and then mine", and increase the prevention and detection of mine water inrush disasters. At present, mine water inrush prevention technology has been included in the national science and technology support plan and key scientific and technological research projects to guide coal mine safety production. ...

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Problems solved by technology

[0005] In the ground geophysical prospecting method, due to the distance from the hydrogeological target body (generally 200-1000m, that is, the buried depth of the coal seam), the resolution in the horizontal and vertical directions is greatly reduced, which seriously affects the exploration accuracy and the reliability of the results. Therefore, It is often used in the initial hydrogeological survey of mines, but it cannot solve the hydrogeological problems encountered in the process of coal mining face mining and roadway excavation

[0006] The mine geophysical prospecting method has been widely used in coal mine hydrological exploration in recent years due to its short distance to the detection target, strong signal response, and high resolution. To complete the detection of the target geological body at a certain depth, it is necessary to meet the length of the long enough survey line when the electrodes are arranged. However, due to the limitation of the length of the roadway that can be constructed in the mine, sometimes it cannot meet the requirements of the exploration depth. At the same time, the rock in the underground roadway is hard or broken. However, the grounding resistance is relatively large, and the coupling between the electrode and the rock formation is poor, which affects the reliability of the detection results; ② The theoretical research of the mine transient electromagnetic method is not perfect, such as the mutual induction problem of the multi-turn small loop coil, the working current The coil size should not be too large, the space limit should not be too large, the influence of the full space effect, the large detection blind area, the interference of the metal environment such as the anchor net support in the roadway space, etc. need to be solved urgently, and affect the accuracy of the detection results; ③ mine Audio-electric perspective has achieved good geological results in the detection of the water-conducting structure inside the roof and floor of the coal mining face and the water-richness of the aquifer. At present, the relationship between the exploration depth and electromagnetic fields of different frequencies has not been established theoretically. The influence law of different geoelectric parameters is not clear

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