Dipole-dipole DC resistivity advance detection method for underground tunnel boring head

Abstract

The present invention discloses a dipole-dipole DC resistivity advance detection method for an underground tunnel boring head, comprising arranging 4 electrodes adjacent to the boring head as power supply electrodes, numbered 1, 2, 3, and 4 respectively; arranging m electrodes at a distance na as measuring electrodes, numbered n+4, n+5, .., n+m+3 respectively, taking n=1-3, (n+m)a≥2d, and d being the maximum target distance of advance detection. The dipole-dipole DC resistivity advance detection method for a tunnel boring head adopted by the present invention has a higher resolution than that of a traditional detection device; only one electrode is moved for each measurement, the error rate is low, the construction efficiency is high, and the underground geoelectric interference can be effectively identified, providing a method for the intelligent reading of the observation instrument; the influence of the electrically inhomogeneous body near the measuring collector MN can be eliminated, and the abnormality in front of the tunnel boring head can be highlighted.

Description

Technical Field

[0001] The invention relates to the technical field of mine geophysical exploration, in particular to a dipole-dipole DC resistivity advance detection method for an underground tunnel boring head. Background Art

[0002] The DC resistivity method is one of the advance detection methods for underground tunnel heading specified in the "Detailed Rules for Coal Mine Water Prevention and Control". At present, the DC resistivity method uses a three-pole or three-point three-pole device for advance detection.

[0003] During the construction of this detection device, one power supply electrode must be arranged at infinity (500-1000m away from the excavation working face). This may cause round-trip inspections due to poor grounding of the infinity electrode or broken wires, resulting in low construction efficiency. At the same time, the resolution of the three-pole device is lower than that of the dipole device. Summary of the invention

[0004] The purpose of the present invention is to provide an advance detection method for dipole-dipole DC resistivity of an underground tunnel boring head, which has higher resolution than traditional detection devices; only one electrode is moved for each measurement, the error rate is low, the construction efficiency is high, and it can effectively identify underground geoelectric interference, providing a method for intelligent reading of observation instruments; it can eliminate the influence of electrically inhomogeneous bodies near the measuring collector MN, and can highlight the abnormality in front of the tunnel boring head.

[0005] To achieve the above-mentioned purpose, the present invention provides a dipole-dipole DC resistivity advance detection method for an underground tunnel boring head, comprising arranging four electrodes adjacent to the boring head as power supply electrodes, numbered 1, 2, 3, and 4 respectively; arranging m electrodes at an interval of na as measuring electrodes, numbered n+4, n+5, . . . , n+m+3 respectively, taking n=1~3, (n+m)a≥2d, and d is the maximum target distance of the advance detection.

[0006] Preferably, the first and second electrodes are selected as power supply electrodes A and B respectively, and the (n+4)th and (n+5)th electrodes are selected as measurement electrodes M and N respectively.

[0007] Preferably, while keeping the supply voltage unchanged, the potential difference between the dipole MN is measured three times continuously and recorded as Calculate the deviation of the potential difference observed three times according to the following formula:

[0008]

[0009]

[0010] If δ i≤3~5%, i=1,2,3, then the average value V of the three observed potential differences shall be used as the potential difference of the measuring dipole MN, otherwise repeat the observation until it meets the requirements, and record the potential difference of the measuring dipole MN and the current intensity in the power supply dipole AB circuit together for calculating the apparent resistivity.

[0011] Preferably, the power supply electrode A is moved to the third electrode position, the positions of other electrodes remain unchanged, and step 3 is repeated.

[0012] Preferably, the power supply electrode B is moved to the fourth electrode position, the positions of other electrodes remain unchanged, and step 3 is repeated.

[0013] Preferably, the measuring electrode M is moved to the (n+6)th electrode position, the positions of other electrodes remain unchanged, and step 3 is repeated.

[0014] Preferably, the power supply electrode B is moved to the second electrode position, the positions of other electrodes remain unchanged, and step 3 is repeated.

[0015] Preferably, the power supply electrode A is moved to the first electrode position, the positions of other electrodes remain unchanged, and step 3 is repeated.

[0016] Preferably, steps 4 to 8 are repeated, with only one electrode being moved each time, and cross-rolling measurement is performed until the measuring electrode N moves to the (n+m+3)th electrode position, ie the measurement is completed.

[0017] Preferably, sort the data and calculate the apparent resistivity The calculated apparent resistivity value is processed by the ratio method, and the calculation formula is as follows:

[0018]

[0019] in, is the average apparent resistivity, F (i) is the ratio of apparent resistivity.

[0020] According to the ratio apparent resistivity calculated in the steps, draw the ratio apparent resistivity section contour map, where the x-coordinate is the advance detection distance, the y-coordinate is the tunnel height, and the contour line value is the ratio apparent resistivity.

[0021] Therefore, the present invention adopts the above-mentioned structure of the tunnel boring head dipole-dipole DC resistivity advance detection method.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of a dipole-dipole DC resistivity device of a tunneling head in an embodiment of a method for advanced detection of dipole-dipole DC resistivity of a tunneling head in an underground tunnel of the present invention;

[0024] Figure 2 It is a construction schematic diagram of a dipole-dipole device observation system of an underground tunnel boring head dipole-dipole DC resistivity advance detection method of the present invention;

[0025] Figure 3 It is a cross-sectional diagram of the ratio apparent resistivity detected by the dipole-dipole DC resistivity advance detection method of the underground tunnel boring head of the present invention;

[0026] Figure 4 It is a design diagram of the geoelectric model of the observation system of the dipole-dipole DC resistivity advance detection method of the underground tunnel boring head of the present invention;

[0027] Figure 5 This is the numerical simulation result of the observation system of the dipole-dipole DC resistivity advance detection method of the underground tunnel boring head of the present invention. DETAILED DESCRIPTION

[0028] For the sake of clarity and conciseness, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual embodiment in order to achieve the developer's specific goals, such as meeting system and business-related constraints, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is a routine task for those skilled in the art who benefit from the disclosure of the present invention.

[0029] Here, it is also necessary to explain that, in order to avoid obscuring the present invention due to unnecessary details, only the device structure and / or processing steps closely related to the solution according to the present invention are shown in the application document, and other details that are not closely related to the present invention are omitted. The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0030] Embodiment 1

[0031] like Figure 1-5 As shown, the present invention provides a dipole-dipole DC resistivity advance detection method for a tunnel boring head, including arranging 26 electrodes behind the boring head according to step 1, wherein m=22 and a fixed electrode distance a=4m.

[0032] According to step 2, four electrodes are arranged near the tunneling head as power supply electrodes, numbered 1, 2, 3, and 4 respectively; 22 electrodes are arranged at intervals of 4 m as measuring electrodes, numbered 5, 6, 7...25, and 26;

[0033] According to step 3, connect electrodes 1 and 2 as power supply electrodes A and B, respectively, connect electrodes 5 and 6 as measuring electrodes M and N, keep the power supply voltage unchanged, and measure the potential difference three times in a row. After valid data is obtained, start step 4;

[0034] According to step 4, only the power supply electrode A is moved to the position of electrode No. 3, the measuring electrode MN remains unchanged, and step 3 is repeated;

[0035] According to step 5, only the power supply electrode B is moved to the position of electrode No. 4, the measuring electrode MN remains unchanged, and step 3 is repeated;

[0036] According to step 6, only the measuring electrode M is moved to the position of electrode No. 7, the power supply electrode AB remains unchanged, and step 3 is repeated;

[0037] According to step 7, only the power supply electrode B is moved to the position of electrode No. 2, the measuring electrode MN remains unchanged, and step 3 is repeated;

[0038] According to step 8, only the power supply electrode A is moved to the position of electrode No. 1, the measuring electrode MN remains unchanged, and step 3 is repeated;

[0039] As described in steps 3 to 8, only one electrode is moved at a time, and the cross-rolling measurement is performed until the measuring electrode N moves to the position of electrode No. 26, and the measurement is completed;

[0040] According to the above steps, the geoelectric model is set up for numerical simulation, and the apparent resistivity cross section is obtained as follows: Figure 5 As shown, there is an obvious low-resistance anomaly 50 to 70 meters behind the tunneling head.

[0041] Therefore, the present invention adopts the above-mentioned structure of the tunnel boring head dipole-dipole DC resistivity advance detection method, which has higher resolution than the traditional detection device; only one electrode is moved for each measurement, the error rate is low, the construction efficiency is high, and it can effectively identify the underground electrical interference, providing a method for the intelligent reading of the observation instrument; it can eliminate the influence of the electrically inhomogeneous body near the measuring collector MN, and can highlight the abnormality in front of the tunnel boring head.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A dipole-dipole DC resistivity advance detection method for underground tunnel boring head, characterized in that: The advance detection method comprises the following steps: Step 1: Arrange electrodes behind the tunneling head; Step 2: Arrange 4 electrodes near the tunneling head as power supply electrodes, numbered 1, 2, 3, and 4 respectively; arrange m electrodes at a distance of na as measuring electrodes, numbered n+4, n+5, ..., n+m+3, where n=1~3. , d is the maximum target distance of advance detection, and a is the distance between two adjacent electrodes; Select the 1st and 2nd electrodes as power supply electrodes A and B respectively, and select the (n+4th) and (n+5th) electrodes as measurement electrodes M and N; Step 3: Keep the supply voltage unchanged and observe the potential difference between the dipole MN three times in a row, which are recorded as , , calculate the deviation of the potential difference observed three times according to the following formula : ； ； if , , then the average value of the three observed potential differences is As the potential difference of the measuring dipole MN, otherwise repeat the observation until it meets the requirements, record the potential difference of the measuring dipole MN and the current intensity in the power supply dipole AB loop together for calculating the apparent resistivity, where: Indicates The potential difference of the dipole MN is measured by the second observation The average value of the potential difference between the three observations difference; Step 4: Move the power supply electrode A to the position of the third electrode, keep the positions of other electrodes unchanged, and repeat step 3; Step 5, move the power supply electrode B to the 4th electrode position, keep the other electrode positions unchanged, and repeat step 3; Step 6, move the measuring electrode M to the (n+6)th electrode position, keep the other electrode positions unchanged, and repeat step 3; Step 7, move the power supply electrode B to the position of the second electrode, keep the positions of other electrodes unchanged, and repeat step 3; Step 8: Move the power supply electrode A to the No. 1 electrode position, keep the other electrode positions unchanged, and repeat step 3; As described in step 3-8, only one electrode is moved at a time, and the cross-rolling measurement is performed until the measuring electrode N moves to the position of the (n+m+3)th electrode, and the measurement is completed; Arrange the data, calculate the apparent resistivity, process the calculated apparent resistivity values ​​using the ratio method to obtain the ratio apparent resistivity, and draw the ratio apparent resistivity section contour map.

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