Roadway surrounding rock loose circle joint inversion method based on geophysical prospecting-drilling

Abstract

The invention provides a geophysical prospecting-drilling combined inversion method and system for a roadway surrounding rock loosening circle, and aims to solve the problem that the existing roadway surrounding rock loosening circle range detection is not accurate and comprehensive enough, improve the detection precision and efficiency, and provide a basis for roadway support design and safety maintenance. The method comprises the following steps: geophysical prospecting is carried out on top and bottom plates and two sides of a roadway by using a geological radar, data processing and preliminary detection are completed, and an approximate range of a loose circle is determined; selecting a representative position for drilling, analyzing the surrounding rock damage and crack conditions by means of a drilling peeping instrument, and judging the surrounding rock damage depth. And comparing the borehole peeping data with a geological radar preliminary detection result, constructing a target function through a least square method, and solving and correcting geological radar parameters. And scanning the roadway again by using the corrected parameters, importing secondary scanning data and drilling peeping data into professional software, constructing and visualizing a three-dimensional model of the roadway surrounding rock loose circle, and visually displaying information such as the shape, the size and the depth of the loose circle. The advantages of geophysical prospecting and drilling are integrated, the detection precision is effectively improved, roadway detection is comprehensively covered, a reliable basis is provided for roadway support design and safety maintenance, and meanwhile cost and time are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of roadway surrounding rock failure detection, and particularly relates to a combined inversion method for the loose circle of roadway surrounding rock based on geophysical exploration - drilling. Background Art

[0002] During the construction and maintenance of roadways, accurately grasping the range of the loose circle of surrounding rock is crucial for ensuring the stability of roadways, optimizing the design of support structures, and ensuring safe production.

[0003] Traditional single detection methods, such as relying solely on ground - penetrating radar for geophysical exploration, although capable of quickly scanning a large area of roadway surrounding rock, are difficult to accurately determine the loose range of surrounding rock due to the complexity of geological conditions and the multi - solution nature of radar signals.

[0004] While simply using the drilling method of borehole peephole, although it can visually observe the failure situation of the surrounding rock inside the borehole, the measurement points are limited, it cannot comprehensively reflect the loose state of the surrounding rock of the entire roadway, and it consumes manpower, material resources, and time. Therefore, developing a method that can integrate the advantages of geophysical exploration and drilling to achieve accurate and comprehensive detection of the loose circle of roadway surrounding rock has important practical significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a combined inversion method and system for the loose circle of roadway surrounding rock based on geophysical exploration - drilling, so as to solve the problem in the prior art that the range of the loose circle of roadway surrounding rock cannot be accurately and comprehensively obtained, improve the accuracy and efficiency of roadway surrounding rock detection, and provide a reliable basis for roadway support design and safety maintenance.

[0006] To achieve the above - mentioned purpose, the present invention mainly provides the following technical solutions:

[0007] The present invention provides a combined inversion method for the loose circle of roadway surrounding rock based on geophysical exploration - drilling, and the method includes the following steps:

[0008] S1. Deployment of geophysical exploration equipment and scanning plan;

[0009] S2. Pretreatment of raw geophysical exploration data;

[0010] S3. Visualization of geophysical exploration data and preliminary determination of the failure range;

[0011] S4. Selection of borehole measurement points and borehole construction;

[0012] S5. Peeping and recording of the condition of the surrounding rock of the borehole;

[0013] S6. Determination of the failure depth of the surrounding rock under borehole peeping;

[0014] S7. Calculation of correction of ground - penetrating radar parameters;

[0015] S8. Secondary precise geophysical prospecting scan;

[0016] S9. Joint data visualization inversion.

[0017] Further, in the above method, as described in step S1, the top and bottom plates and both sides of the entire roadway are scanned and detected in a full-coverage manner using a ground-penetrating radar (GPR). The vertical detection depth of both sides is set to d r1 , and the vertical detection depth of the top and bottom plates is d r2 . According to the geological conditions and detection requirements of the roadway, a radar antenna with an appropriate frequency is selected, and parameters such as the transmission power and sampling rate of the radar are set to ensure that it can effectively penetrate the target depth and obtain clear radar reflection signals. During the scanning process, the radar antenna is moved uniformly at a certain interval.

[0018] Further, in the above method, as described in step S2, the collected original radar data is recorded and preliminarily preprocessed in real time, including operations such as denoising and gain adjustment to improve the data quality. The geophysical exploration data is processed through visualization to obtain the geological radar reflection wave profile corresponding to the top-bottom plate and the sides of the entire roadway.

[0019] Further, in the above method, as described in step S3, according to the geological radar reflection wave information, if there are no original geological structures such as cavities, fractures, and broken zones in the exploration area, the isophase axis of the geological radar reflection wave should be continuous and there should be no diffraction phenomenon. The geological radar waveform significantly shows two different regions in the detection depth direction: a waveform clear region and a waveform fuzzy region, and there is an obvious boundary between the two, and this boundary is regarded as the boundary of the surrounding rock loosening zone.

[0020] Further, in the above method, as described in step S4, multiple representative positions are selected in the roadway as borehole peep measurement points. Three boreholes are arranged at each measurement point to conduct borehole peeping on the roof and both sides respectively. The borehole depth of both sides is d p1 , and the borehole depth of the roof is d p2 . During the borehole drilling process, professional borehole drilling equipment and guiding devices are used to ensure the verticality and accuracy of the boreholes.

[0021] Further, in the above method, as described in step S5, the borehole peeping instrument is placed into the borehole to conduct detailed observation and recording of the crack distribution, fragmentation degree, rock integrity, etc. of the surrounding rock of the borehole wall.

[0022] Further, in the above method, as described in step S6, by directly observing the fragmentation and fracture development of the surrounding rock at different depths in the borehole, the damage depth of the surrounding rock of the roof, bottom plate, and sides of the roadway is determined, and accurate loosening range data of the surrounding rock at the measurement points is obtained.

[0023] Further, in the above method, as described in step S7, compare the accurate loose circle range data obtained by borehole peephole with the preliminary geological radar detection results, establish a mathematical relationship model, construct an objective function using the least squares method, solve the system of equations, obtain the corrected geological radar detection parameters, and combine the reflection wave profile information to constrain the parameter value range, specifically as follows:

[0024] Let the surrounding rock loosening depth at a certain measurement point determined by borehole peephole be d p , and the preliminary geological radar detection shows that the depth corresponding to this boundary is d r . Let the detection parameters of the geological radar be vector where p i represents parameters such as radar wave velocity v; measurement time window T; dielectric constant ∈.

[0025] The geological radar detection depth d r has the following relationship with these parameters (considering the round-trip propagation of radar waves).

[0026] Construct an objective function using the least squares method to measure the difference between the radar detection depth and the borehole peephole depth. The objective function is:

[0027]

[0028] In the formula, m is the number of samples of the comparison data, represents the radar detection depth at the kth sample point under the parameter , and d p,k is the true depth determined by borehole peephole at the kth sample point.

[0029] By taking the partial derivative of the objective function with respect to the parameter vector and setting it to zero, that is:

[0030]

[0031] Solve the above system of equations to obtain the parameter vector that minimizes the objective function. This is the corrected geological radar detection parameter. During the solution process, combine the loose circle boundary information determined in the geological radar reflection wave profile to further constrain the value range of the parameters, so that the obtained is more accurate, so that the adjusted radar detection result can match the borehole peephole result.

[0032] Further, in the above method, as described in step S8, using the corrected radar parameter settings, the roadway is scanned again by the ground penetrating radar in a full-coverage manner. After parameter optimization, the ground penetrating radar can more accurately identify the loosening state of surrounding rocks at different depths, reducing misjudgment and missed judgment. Further process and analyze the data obtained from the secondary scan to extract more accurate characteristic information of the surrounding rock loosening zone.

[0033] Further, in the above method, as described in step S9, import the accurate radar data obtained from the secondary scan and the data verified by borehole peephole into professional inversion software such as Surfer and Rhino to construct a three-dimensional model of the surrounding rock loosening zone of the roadway. With the visualization function of the software, intuitively display information such as the shape, size, and depth of the loosening zones of the roof, floor, and two sides of the entire roadway. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. The drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a flow chart of a combined inversion method for the surrounding rock loosening zone of a roadway based on geophysical exploration - drilling;

[0036] Figure 2 It is a schematic diagram of the ground penetrating radar detecting the roof, floor, and two sides of the roadway;

[0037] Figure 3 It is a schematic diagram of the correction of the ground penetrating radar parameters of the present invention. Detailed Embodiments

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0039] The present invention provides a combined inversion method for the surrounding rock loosening zone of a roadway based on geophysical exploration - drilling, and its specific steps are as follows:

[0040] S1. Use geophysical exploration equipment to conduct on-site detection of the roadway.

[0041] Use the ground penetrating radar (GPR) to conduct full-coverage scanning detection on the roof, floor, and two sides of the entire roadway. Set the vertical detection depth of the two sides to be d r1 , and the vertical detection depth of the roof and floor to be d r2According to the geological conditions and detection requirements of the roadway, select a radar antenna with an appropriate frequency, and set parameters such as the radar's transmit power and sampling rate to ensure that it can effectively penetrate the target depth and obtain clear radar reflection signals. During the scanning process, move the radar antenna uniformly at a certain spacing.

[0042] S2. Geophysical exploration data processing and extraction.

[0043] Perform preliminary processing on the collected original radar data. Use the built-in denoising algorithm of the software, such as wavelet denoising algorithm, to remove the noise interference in the data; through the gain adjustment function, enhance the display effect of weak signals to make the radar reflection image clearer. Subsequently, perform visualization processing on the processed data to generate the geological radar reflection wave profile diagrams corresponding to the full-length roadway roof-floor and rib parts.

[0044] S3. Preliminary determination of the loose circle range of the roadway based on geophysical exploration.

[0045] Based on the continuity of the in-phase axis of the reflection wave, diffraction phenomenon, and the boundary between the clear waveform area and the fuzzy area in the reflection wave profile diagram, preliminarily judge the range of the surrounding rock loose circle. The reflection wave profile clearly shows two different regions in the detection depth direction: the clear waveform area and the fuzzy waveform area, and there is an obvious boundary between the two, and this boundary is regarded as the boundary of the surrounding rock loose circle.

[0046] S4. Construct boreholes to conduct roadway surrounding rock peeping.

[0047] Select multiple representative positions in the roadway as borehole peeping measurement points. Arrange 3 boreholes at each measurement point to conduct borehole peeping on the roof and two ribs respectively. The depth of the boreholes on the two ribs is d p1 , and the depth of the borehole on the roof is d p2 .

[0048] S5. Analyze the surrounding rock damage and crack conditions in the borehole peeping pictures.

[0049] Put the borehole peeping instrument into the borehole, and conduct detailed observation and recording on the crack distribution, fragmentation degree, rock integrity, etc. of the wall rock of the borehole.

[0050] S6. Obtain the data of the loose depth of the surrounding rock of the roadway roof-floor and rib parts.

[0051] Through the direct observation of the fragmentation and crack development conditions of the surrounding rock at different depths in the borehole, determine the damage depth of the surrounding rock of the roadway roof-floor and rib parts, and obtain the accurate loose range data of the surrounding rock at the measurement points.

[0052] S7. Geological radar parameter correction.

[0053] Compare the accurate loose circle range data obtained by borehole peephole with the preliminary detection results of ground penetrating radar, establish a mathematical relationship model, construct an objective function using the least squares method, solve the equations, obtain the corrected ground penetrating radar detection parameters, and combine the reflection wave profile information to constrain the parameter value range, specifically as follows:

[0054] Let the surrounding rock loosening depth at a certain measuring point determined by borehole peephole be d p , and the ground penetrating radar preliminary detection shows that the depth corresponding to this boundary is d r . Let the detection parameters of the ground penetrating radar be vector where

[0055] p i represents parameters such as radar wave velocity v, measurement time window T, and dielectric constant ∈.

[0056] The ground penetrating radar detection depth d r has the following relationship with these parameters (considering the round-trip propagation of radar waves)

[0057] Construct an objective function using the least squares method to measure the difference between the radar detection depth and the borehole peephole depth. The objective function is:

[0058]

[0059] In the formula, m is the number of samples of the comparison data, represents the radar detection depth at the k-th sample point under the parameter , and d p,k is the true depth determined by borehole peephole at the k-th sample point.

[0060] By taking the partial derivative of the objective function with respect to the parameter vector and setting it to zero, that is:

[0061]

[0062] Solve the above equations to obtain the parameter vector that minimizes the objective function. This is the corrected ground penetrating radar detection parameter. During the solution process, combine the loose circle boundary information determined in the ground penetrating radar reflection wave profile to further constrain the value range of the parameters, so that the obtained is more accurate, and thus the adjusted radar detection result can match the borehole peephole result.

[0063] S8. Secondary scanning and precise detection of ground penetrating radar.

[0064] Using the corrected radar parameter settings, conduct a full-coverage geological radar scan of the roadway again. After parameter optimization, the geological radar can more accurately identify the loosening state of surrounding rocks at different depths, reducing misjudgment and missed judgment. Further process and analyze the data obtained from the secondary scan to extract more accurate characteristic information of the surrounding rock loosening zone.

[0065] S9. Visual inversion.

[0066] Import the accurate radar data obtained from the secondary scan and the data verified by borehole peeping into professional inversion software such as Surfer and Rhino to construct a three-dimensional model of the surrounding rock loosening zone of the roadway. With the visualization function of the software, intuitively display information such as the shape, size, and depth of the loosening zones at the roof, floor, and two sides of the entire roadway.

[0067] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

[0068] In order to enable relevant technical personnel to master the geological radar parameter correction method, the following uses a simple case to illustrate the specific implementation manner of S6.

[0069] Suppose in a simple roadway detection scenario, technicians need to correct three parameters: the radar wave velocity ν, the measurement time window T, and the dielectric constant ε.

[0070] Initial parameter setting: the radar wave velocity v0 = 0.1 m / ns; the measurement time window T0 = 60 ns; the dielectric constant ∈0 = 4.

[0071] Select 3 positions in the roadway for borehole peeping to determine the actual depths of the surrounding rock loosening boundaries at these 3 positions: d p,1 = 2.5 m; d p,1 = 3.0 m; d p,1 = 2.8 m;

[0072] The geological radar detection depth d r The relationship with these parameters is simplified to (Considering the round-trip propagation of radar waves)

[0073] Suppose under the initial parameters, the corresponding depths detected by the geological radar are: Here the parameter vector

[0074] According to the least squares method, construct the objective function To measure the difference between the radar detection depth and the borehole peeping depth, the objective function is:

[0075]

[0076] Will Substituting into the above formula, we get:

[0077]

[0078] For the objective function Find the partial derivatives with respect to v, T, ∈ respectively:

[0079]

[0080]

[0081]

[0082] make Through simple numerical calculations, the corrected parameter values ​​are obtained:

[0083] v * =0.105m, T * =65ns,∈ * =4.2;

[0084] Through the above simple example, using the borehole peeking data, the radar wave velocity, measurement time window and dielectric constant were corrected based on the least squares method, so that the geological radar detection results are closer to the actual boundary depth of the surrounding rock loosening.

Claims

1. A geophysical-drilling joint inversion method for the loose circle of roadway surrounding rock, characterized in that It includes the following steps: Step S1: Deployment of geophysical exploration equipment and scanning planning; Step S1: Deployment of geophysical exploration equipment and scanning planning; Step S2: Pretreatment of raw geophysical exploration data; Step S3: Visualization of geophysical exploration data and preliminary determination of the damage range; Step S4: Selection of borehole measuring points and borehole construction; Step S5: Peering record of the surrounding rock condition of the borehole; Step S6: Determination of the surrounding rock failure depth under borehole peering; Step S7: Correction calculation of geological radar parameters; Step S8: Secondary precise geophysical exploration scanning; Step S9: Joint data visualization inversion.

2. The geophysical exploration - drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, wherein As described in step S1, the whole roadway's roof, floor and two sides are scanned and detected in a full-coverage manner using a ground penetrating radar, and the vertical detection depth of the two sides is set to d r1 , and the vertical detection depth of the roof and floor is d r2 ; According to the roadway geological conditions and detection requirements, a radar antenna with an appropriate frequency is selected, and parameters such as the radar's transmission power and sampling rate are set to ensure that it can effectively penetrate the target depth and obtain a clear radar reflection signal. During the scanning process, the radar antenna is moved uniformly at a certain interval.

3. The geophysical exploration - drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, wherein, As described in Step S2, the collected raw radar data is recorded in real time, and preliminary pretreatment operations such as denoising and gain adjustment are carried out. The geophysical exploration data is visually processed to obtain the geological radar reflection wave profile corresponding to the roof-floor and sides of the full-length roadway.

4. The geophysical exploration-drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, characterized in that, As described in Step S3, according to the geological radar reflection wave information, if there are no original geological structures such as cavities, fractures, and broken zones in the exploration area, the isophase axis of the geological radar reflection wave should be continuous and there should be no diffraction phenomenon; based on the waveform clear area and waveform fuzzy area presented by the geological radar waveform in the detection depth direction, the boundary between the two is regarded as the boundary of the surrounding rock loosening circle.

5. The geophysical exploration - drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, characterized in that As described in Step 4, select multiple representative positions in the roadway as borehole peep measurement points. Three boreholes are arranged at each measurement point to conduct borehole peeping on the roof and both sides respectively. The depth of the boreholes on both sides is d p1 , and the depth of the boreholes on the roof is d p2 ; During the borehole drilling process, professional borehole drilling equipment and guiding devices are used to ensure the verticality and accuracy of the boreholes.

6. The geophysical exploration - drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, characterized in that, As described in Step S5, the borehole peering instrument is placed into the borehole, and the crack distribution, fragmentation degree, rock integrity, etc. of the wall rock of the borehole are carefully observed and recorded.

7. The geophysical exploration - drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, characterized in that As described in Step S6, by directly observing the fragmentation and fracture development conditions of the surrounding rock at different depths in the borehole, the surrounding rock failure depth of the roof-floor and sides of the roadway is determined, and accurate loosening range data of the surrounding rock at the measuring point is obtained.

8. The geophysical exploration-drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 1, wherein, As described in Step S7, compare the accurate loosening circle range data obtained by borehole peering with the preliminary detection results of the geological radar, establish a mathematical relationship model, use the least squares method to construct an objective function, solve the equations, and obtain the corrected geological radar detection parameters. Combine the reflection wave profile information to constrain the parameter value range, specifically as follows: The loosening depth of the surrounding rock at a certain measuring point determined by borehole peep is d p , and the preliminary detection by ground penetrating radar shows that the depth corresponding to this boundary is d r . Let the detection parameters of the ground penetrating radar be a vector where p i represents, for example, the radar wave velocity v; the measurement time window T; the dielectric constant ∈. Detection depth d of ground penetrating radar r The relationship with these parameters is (considering the round-trip propagation of radar waves). Construct the objective function using the least squares method To measure the difference between the radar detection depth and the borehole peephole depth, the objective function is as follows: where m is the sample size of the comparison data, represents the radar detection depth of the k-th sample point at parameter , and d p,k is the true depth determined by borehole peeping at the k-th sample point. By taking the partial derivative of the objective function with respect to the parameter vector and setting it to zero, i.e.: Solve the above equations to obtain the parameter vector that minimizes the objective function This is the corrected ground penetrating radar detection parameter 9. The geophysical exploration-drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 8, characterized in that As described in Step S1, secondary precise geophysical exploration scanning: Use the corrected radar parameter settings to conduct a full-coverage geological radar scan of the roadway again, further process and analyze its data, and extract more accurate surrounding rock loosening circle characteristic information.

10. The geophysical-drilling combined inversion method for the loose circle of roadway surrounding rock according to claim 9, wherein As described in Step S1, import the precise radar data obtained from the secondary scan and the data verified by borehole peering into professional inversion software, construct a three-dimensional model of the surrounding rock loosening circle of the roadway, and with the help of the software visualization function, visually display the shape, size, depth, etc. of the loosening circles of the roof-floor and two sides of the full-length roadway.

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