A method for constructing a non-uniform wave velocity field model of an underground mine

Abstract

The present invention belongs to the technical field of mine safety monitoring and rock mass engineering detection, and specifically discloses a method for constructing a non-uniform wave velocity field model for an underground mine. The method includes selecting a variety of rock materials, manufacturing a plurality of regular blocks and measuring the reference wave velocity, then manufacturing rock specimens and conducting wave velocity test experiments, and constructing a wave velocity quantization formula by fitting the experimental data; constructing a three-dimensional block model according to the spatial characteristics of the prediction area, dividing it into a plurality of block unit models, and generating a lithology block unit model through spatial interpolation; constructing a three-dimensional engineering geological characterization model, extracting geological feature data from the three-dimensional engineering geological characterization model, and using the wave velocity quantization formula to assign wave velocities to all lithology block unit models to obtain a three-dimensional non-uniform wave velocity field model. The present invention can construct a wave velocity field model that is more in line with the actual situation of underground mines, overcome the limitations of the constant wave velocity assumption in traditional models, and improve the reliability of microseismic monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of mine safety monitoring and rock mass engineering detection, and specifically discloses a method for constructing a non-uniform wave velocity field model for an underground mine. Background Art

[0002] China's mineral resources are rich in reserves. According to incomplete statistics, the total number of underground mines across the country has exceeded 10,000, and small and medium-sized mines dominate. Under the release and implementation of the Safety Regulations for Metal and Non-Metal Underground Mines, the application of microseismic monitoring technology that complies with the specifications of the "Six Major Systems" for safety refuge has become a mandatory requirement for mine safety production. Microseismic monitoring technology is based on the propagation speed of elastic waves in the medium, and the accuracy of earthquake source location largely depends on the three-dimensional spatial distribution of the wave velocity field. However, in underground mines, the rock mass as the propagation medium has characteristics such as discontinuity and non-uniformity. It is not only superimposed with the in-situ stress that changes with depth, but also affected by artificial engineering structures such as roadways and goafs, resulting in a complex non-uniform characteristic of the rock mass wave velocity field, which has a significant impact on the propagation path and arrival time calculation of microseismic signals.

[0003] Traditional uniform wave velocity models or zoned uniform models constructed according to lithology do not comprehensively consider the influence of rock mass structure characteristics, in-situ stress effects, and underground mine goafs, resulting in a wave velocity inversion error exceeding ±15%, making it difficult to meet the requirement of the Safety Regulations for Metal and Non-Metal Underground Mines for the disaster warning response time ≤ 30 seconds. Therefore, based on the quantification of the influence of key geological parameters on wave velocity, and integrating data such as the characteristics of rock mass fractures, in-situ stress laws, and the distribution of underground mine goafs in the mine, the present invention proposes a method for constructing a non-uniform wave velocity field model for an underground mine, which can effectively overcome the limitations of the constant wave velocity assumption in traditional models and improve the reliability of microseismic monitoring. Summary of the Invention

[0004] In order to solve the problems in the existing model such as the constant wave velocity assumption, the failure to comprehensively consider the influence of rock mass structure characteristics, in-situ stress effects, and underground mine goafs, resulting in an excessive wave velocity inversion error, the present invention proposes a method for constructing a non-uniform wave velocity field model for an underground mine.

[0005] The present invention provides a method for constructing a non-uniform wave velocity field model for an underground mine, including the following steps:

[0006] S1. Select a variety of rock materials, make a plurality of regular blocks, and measure the reference wave velocity of each of the regular blocks respectively;

[0007] S2. Use the regular blocks to make rock specimens, conduct wave velocity test experiments on each of the rock specimens respectively, obtain experimental data, and construct a wave velocity quantification formula by fitting the experimental data;

[0008] S3. Construct a three-dimensional block model of the prediction area according to the spatial characteristics of the prediction area, select the unit size, divide the three-dimensional block model into multiple block unit models according to the unit size, and generate a lithology block unit model by performing spatial interpolation on the block unit models;

[0009] S4. Based on the mapping relationship between the RQD value and the fracture density, the lithology data of the prediction area, the in-situ stress test data of the prediction area, the spatial characteristics of the prediction area, and the three-dimensional block model, construct a three-dimensional engineering geological characterization model;

[0010] S5. Extract the geological feature data of the three-dimensional engineering geological characterization model, and assign wave velocities to multiple lithology block unit models based on the geological feature data using the wave velocity quantization formula. Traverse all the lithology block unit models to obtain a three-dimensional non-uniform wave velocity field model;

[0011] The step S2 includes the following steps:

[0012] S201. Use the Brazilian splitting method to prefabricate different fracture densities and different fracture inclinations in multiple regular blocks to obtain multiple rock specimens;

[0013] S202. Place the rock specimens in a fixing device, and perform wave velocity test experiments on each rock specimen under different normal stress conditions, and record the experimental data. The experimental data includes wave velocity, the fracture density of the rock specimen, the normal stress received by the rock specimen, and the fracture inclination of the rock specimen. Among them, the fracture inclination is the included angle between the fracture and the normal stress;

[0014] S203. Based on the experimental data, draw an experimental data curve, construct a fitting formula, and then construct the wave velocity quantization formula. The wave velocity quantization formula is shown in formula (1):

[0015] (1)

[0016] In the formula, v represents the wave velocity, v0 represents the reference wave velocity, m represents the fracture density of the rock specimen, p represents the normal stress received by the rock specimen, α represents the fracture inclination of the rock specimen, A represents the sine weight coefficient of the fracture inclination, B represents the cosine weight coefficient of the fracture inclination, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, and E represents the comprehensive correction coefficient. Among them, the sine weight coefficient of the fracture inclination, the cosine weight coefficient of the fracture inclination, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data.

[0017] A method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the step S3 includes the following steps:

[0018] S301. Construct the three-dimensional block model according to the spatial characteristics of the prediction area;

[0019] S302. Select the unit size, and divide the three-dimensional block model into a plurality of block unit models with the same size according to the spatial characteristics of the prediction area and the unit size;

[0020] S303. Based on the lithology data of the prediction area, perform spatial interpolation on each block unit model respectively to generate a plurality of lithology block unit models.

[0021] A method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the spatial characteristics of the prediction area in the step S3 include: the geometric parameters of the prediction area, the three-dimensional layout of the voids in the prediction area, the geometric parameters of the voids in the prediction area, the number of boreholes in the prediction area, the volume of the boreholes in the prediction area, and the shape of the boreholes in the prediction area;

[0022] Among them, the voids in the prediction area include the roadways and the mined-out areas in the prediction area.

[0023] A method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the step S4 includes the following steps:

[0024] S401. Extract the three-dimensional layout and geometric parameters of the roadways in the prediction area based on the engineering structure diagram of the prediction area, simulate the roadways as pipelines, and construct an interlaced and connected roadway model;

[0025] S402. Extract the three-dimensional layout and geometric parameters of the mined-out areas in the prediction area based on the engineering structure diagram of the prediction area, simulate the mined-out areas in the prediction area as cuboids of different sizes, and construct a mined-out area model;

[0026] S403. Use the Boolean union operation to merge the roadway model and the mined-out area model to obtain the void model of the prediction area, and obtain the void information in the prediction area;

[0027] S404. Based on the in-situ stress test data of the prediction area, construct an in-situ stress calculation formula through outlier screening and multiple linear regression analysis to obtain the in-situ stress of the prediction area;

[0028] S405. Collect cores from multiple of the predicted regions, take images of the cores, and obtain the RQD value of the cores;

[0029] S406. Input the RQD value into the preset mapping relationship between the RQD value and the fracture density to obtain the fracture density;

[0030] S407. Based on the goaf information of the predicted region, the in-situ stress of the predicted region, the fracture density, and the lithology data of the predicted region, perform spatial interpolation on the lithology block unit model to construct the three-dimensional engineering geological characterization model.

[0031] According to a method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the step S405 includes the following steps:

[0032] S415. Collect cores from multiple of the predicted regions and take multiple images of the cores of the predicted regions;

[0033] S425. Based on the OCR technology, respectively identify the identification information in each core image, generate a file containing the borehole number and the borehole depth, and uniformly name the file;

[0034] S435. Parse the core length of the borehole corresponding to the core image according to the naming of the file;

[0035] S445. Automatically crop the effective region of the core through a target detection algorithm, identify the lithology name of the effective region, and label the corresponding lithology code;

[0036] S455. Use a semantic segmentation model to identify the length of the effective region and calculate the RQD value of the core.

[0037] According to a method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the lithology data of the predicted region includes: the borehole number, the borehole depth, the core length of the borehole, the lithology name, the lithology code, the length of the effective region, and the RQD value.

[0038] According to a method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the preset mapping relationship between the RQD value and the fracture density in the step S406 is shown in formula (2):

[0039] (2)

[0040] In the formula, n represents the fracture density; f(x) represents the fracture distribution function; x represents the fracture spacing;

[0041] Among them, the crack spacing is obtained by fitting the experimental data curve.

[0042] According to a method for constructing a non-uniform wave velocity field model of an underground mine according to some embodiments of the present application, the step S5 includes the following steps:

[0043] S501. Preset the mapping relationship between lithology data and reference wave velocity according to the various rock materials and the measured reference wave velocity.

[0044] S502. Assign reference wave velocities to each of the lithology block unit models according to the preset mapping relationship between lithology data and reference wave velocity, and traverse all the lithology block unit models to obtain a three-dimensional block reference wave velocity model.

[0045] S503. Read the in-situ stress, the fracture density, the fracture dip angle of the prediction area in the three-dimensional engineering geological characterization model, and the goaf information in the prediction area.

[0046] S504. Calculate the normal stress based on the in-situ stress of the prediction area.

[0047] S505. Construct a wave velocity quantization formula for the non-uniform wave velocity field based on the wave velocity quantization formula, as shown in formula (3):

[0048] (3)

[0049] In the formula, V represents the wave velocity of the non-uniform wave velocity field, v0 represents the reference wave velocity, n represents the fracture density, P represents the normal stress, β represents the fracture dip angle, A represents the sine weight coefficient of the fracture dip angle, B represents the cosine weight coefficient of the fracture dip angle, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, and E represents the comprehensive correction coefficient, where the sine weight coefficient of the fracture dip angle, the cosine weight coefficient of the fracture dip angle, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data;

[0050] S506. Substitute the fracture density, the fracture dip angle, and the normal stress into the wave velocity quantization formula of the non-uniform wave velocity field to update the wave velocity of the three-dimensional block reference wave velocity model, and obtain the three-dimensional non-uniform wave velocity field model. Among them, in combination with the goaf information in the prediction area, the wave velocity of the goaf is directly updated to the atmospheric wave velocity.

[0051] A method for constructing a non-uniform wave velocity field model of an underground mine proposed by the present invention can comprehensively consider the influence of rock mass structure characteristics, in-situ stress action and underground mine goafs to quantify the wave velocities corresponding to different regions, and generate a three-dimensional non-uniform wave velocity field characterization model that better conforms to the actual situation of the underground mine by combining geostatistical interpolation, effectively making up for the large wave velocity inversion error caused by the traditional uniform wave velocity model or the zonal uniform model constructed according to lithology, and laying a foundation for high-precision microseismic positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic flow chart of a method for constructing a non-uniform wave velocity field model of an underground mine according to Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The following further describes in detail the embodiments of the present invention with reference to the drawings. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0054] Embodiment 1. The present embodiment provides a method for constructing a non-uniform wave velocity field model of an underground mine, as Figure 1 shown, including the following steps:

[0055] S1. Select a variety of rock materials, make a plurality of regular blocks, and measure the reference wave velocity of each regular block respectively.

[0056] S2. Use the regular blocks to make rock specimens, conduct wave velocity test experiments on each rock specimen respectively to obtain experimental data, and construct a wave velocity quantization formula by fitting the experimental data.

[0057] S3. Construct a three-dimensional block model of the prediction area according to the spatial characteristics of the prediction area, select the unit size, divide the three-dimensional block model into a plurality of block unit models according to the unit size, and generate a lithology block unit model by spatial interpolation of the block unit models.

[0058] S4. Based on the mapping relationship between RQD value and fracture density, the lithology data of the prediction area, the in-situ stress test data of the prediction area, the spatial characteristics of the prediction area and the three-dimensional block model, construct a three-dimensional engineering geological characterization model.

[0059] S5. Extract the geological feature data of the three-dimensional engineering geological characterization model, assign wave velocities to a plurality of lithology block unit models based on the geological feature data using the wave velocity quantization formula, and traverse all lithology block unit models to obtain a three-dimensional non-uniform wave velocity field model.

[0060] Embodiment 2. The present embodiment provides a method for constructing a non-uniform wave velocity field model of an underground mine, including the following steps:

[0061] S1. Select a variety of rock materials, fabricate multiple regular blocks, and measure the reference wave velocity of each regular block respectively.

[0062] S201. Use the Brazilian splitting method to prefabricate different fracture densities and different fracture inclinations in multiple regular blocks respectively to obtain multiple rock specimens.

[0063] S202. Place the rock specimens in a fixing device, conduct wave velocity test experiments on each rock specimen respectively under different normal stress conditions, and record the experimental data. The experimental data includes wave velocity, fracture density of the rock specimen, normal stress received by the rock specimen, and fracture inclination of the rock specimen. Among them, the fracture inclination is the angle between the fracture and the normal stress.

[0064] S203. Based on the experimental data, draw an experimental data curve, construct a fitting formula, and then construct a wave velocity quantification formula. The wave velocity quantification formula is shown in formula (1):

[0065] (1)

[0066] In the formula, v represents the wave velocity, v0 represents the reference wave velocity, m represents the fracture density of the rock specimen, p represents the normal stress received by the rock specimen, α represents the fracture inclination of the rock specimen, A represents the sine weight coefficient of the fracture inclination, B represents the cosine weight coefficient of the fracture inclination, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, and E represents the comprehensive correction coefficient. Among them, the sine weight coefficient of the fracture inclination, the cosine weight coefficient of the fracture inclination, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data. Preferably, in this embodiment, the sine weight coefficient of the fracture inclination is used to control the contribution weight of the sine term of the fracture inclination to the wave velocity; the normal stress gain coefficient is used to adjust the amplification ratio of the normal stress in the logarithmic function, reflecting the positive enhancement effect of the normal stress on the wave velocity; the fracture density attenuation coefficient is used to control the weakening effect of the fracture density on the wave velocity, and the larger the value, the more significant the negative impact of the fracture density on the wave velocity; the comprehensive correction coefficient is used to correct the error of data fitting.

[0067] S301. Construct a three-dimensional block model according to the spatial characteristics of the prediction area.

[0068] S302. Select the element size, and divide the three-dimensional block model into multiple block element models with the same size according to the spatial characteristics of the prediction area and the element size. Preferably, in this embodiment, the spatial characteristics of the prediction area include: geometric parameters of the prediction area, three-dimensional layout of the voids in the prediction area, geometric parameters of the voids in the prediction area, number of boreholes in the prediction area, volume of boreholes in the prediction area, and shape of boreholes in the prediction area. Among them, the voids in the prediction area include roadways in the prediction area and goafs in the prediction area.

[0069] S303. Based on the lithology data of the prediction area, perform spatial interpolation on each block unit model respectively to generate multiple lithology block unit models.

[0070] S401. Extract the three-dimensional layout and geometric parameters of the roadways in the prediction area based on the engineering structure diagram of the prediction area, simulate the roadways as pipelines, and construct an intersecting and connected roadway model.

[0071] S402. Extract the three-dimensional layout and geometric parameters of the goafs in the prediction area based on the engineering structure diagram of the prediction area, simulate the goafs in the prediction area as cuboids of different sizes, and construct a goaf model.

[0072] S403. Use the Boolean union operation to merge the roadway model and the goaf model to obtain the goaf model of the prediction area, and obtain the goaf information in the prediction area.

[0073] S404. Based on the in-situ stress test data of the prediction area, construct an in-situ stress calculation formula through outlier screening and multiple linear regression analysis to obtain the in-situ stress of the prediction area.

[0074] S405. Collect the cores of multiple prediction areas, take images of the cores, and obtain the RQD values of the cores. Preferably, step S405 in this embodiment includes steps S415 - S455, which are specifically as follows.

[0075] S415. Collect the cores of multiple prediction areas, mark the corresponding borehole information, and take multiple images of the cores in the prediction area. Preferably, the borehole information in this embodiment includes borehole number, borehole depth, core length of the borehole, etc.

[0076] S425. Based on the OCR technology, identify the identification information in each core image respectively, generate a file containing the borehole number and borehole depth, and uniformly name the file.

[0077] S435. Analyze the core length of the borehole corresponding to the core image according to the naming of the file.

[0078] S445. Automatically crop the effective area of the core through the target detection algorithm, identify the lithology name of the effective area, and mark the corresponding lithology code.

[0079] S455. Use the semantic segmentation model to identify the length of the effective area and calculate the RQD value of the core.

[0080] S406. Input the RQD value into the preset mapping relationship between the RQD value and the fracture density to obtain the fracture density. Preferably, the preset mapping relationship between the RQD value and the fracture density in this embodiment is shown in formula (2):

[0081] (2)

[0082] In the formula, n represents the fracture density; f(x) represents the fracture distribution function; x represents the fracture spacing. Preferably, the fracture spacing is obtained by fitting the experimental data curve.

[0083] S407. Based on the goaf information of the prediction area, the in-situ stress of the prediction area, the fracture density, and the lithology data of the prediction area, perform spatial interpolation on the lithology block unit model to construct a three-dimensional engineering geological characterization model. Preferably, in this embodiment, the lithology data of the prediction area includes: borehole number, borehole depth, core length of the borehole, lithology name, lithology code, length of the effective area, and RQD value.

[0084] S501. Preset the mapping relationship between lithology data and reference wave velocity according to various rock materials and the measured reference wave velocity.

[0085] S502. Assign the reference wave velocity to each lithology block unit model respectively according to the preset mapping relationship between lithology data and reference wave velocity, and traverse all lithology block unit models to obtain a three-dimensional block reference wave velocity model.

[0086] S503. Read the in-situ stress, fracture density, fracture dip angle of the prediction area in the three-dimensional engineering geological characterization model, and the goaf information in the prediction area.

[0087] S504. Calculate the normal stress based on the in-situ stress of the prediction area.

[0088] S505. Construct a wave velocity quantization formula for the non-uniform wave velocity field based on the wave velocity quantization formula, as shown in formula (3):

[0089] (3)

[0090] In the formula, V represents the wave velocity of the non-uniform wave velocity field, v0 represents the reference wave velocity, n represents the fracture density, P represents the normal stress, β represents the fracture dip angle, A represents the sine weight coefficient of the fracture dip angle, B represents the cosine weight coefficient of the fracture dip angle, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, and E represents the comprehensive correction coefficient, where the sine weight coefficient of the fracture dip angle, the cosine weight coefficient of the fracture dip angle, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data.

[0091] S506. Substitute the fracture density, fracture dip angle, and normal stress into the wave speed quantification formula of the non-uniform wave speed field to update the wave speed of the three-dimensional block reference wave speed model, and obtain a three-dimensional non-uniform wave speed field model. Among them, in combination with the goaf information in the prediction area, directly update the wave speed of the goaf to the atmospheric wave speed.

[0092] Example 3. This example provides a method for constructing a non-uniform wave speed field model for an underground mine, including the following steps:

[0093] Step 1. Collect granite rock samples at a certain mine site and prepare them into regular blocks of 10 cm × 5 cm × 5 cm, and measure the reference wave speed of each regular block.

[0094] Step 2. Perform Brazilian splitting on each regular block to form penetrating fractures for the test. Control the fracture density determined according to the rock length to be 10 - 30 fractures / m, and the fracture angle to be 50 - 90°, to obtain a plurality of rock specimens. Place the rock specimens with different fracture densities and fracture angles in a fixing device for fixing, apply a normal stress of 1 - 30 MPa at both ends, and simultaneously conduct wave speed test experiments at both ends of the rock specimens, and record the experimental data.

[0095] Step 3. Fit the experimental data to establish a wave speed quantification formula considering fracture density, fracture angle, and normal stress, as shown in formula (4):

[0096] (4)

[0097] In the formula, v represents the wave speed, v0 represents the reference wave speed, m represents the fracture density of the rock specimen, p represents the normal stress applied to the rock specimen, and α represents the fracture dip angle of the rock specimen, that is, the angle between the fracture and the normal stress.

[0098] Step 4. Based on the 596 borehole data in the mine, organize the lithology database, including lithology name, lithology code, starting and ending depths, and percentages, and classify and merge the lithologies with similar mineral compositions and similar mechanical properties, as shown in Table 1. Preferably, in this example, the starting and ending depths refer to the length of the effective area of the core.

[0099] Table 1 Lithology database of this example

[0100]

[0101] Step 5. According to the spatial characteristics of the predicted area of the mine, a three-dimensional block model with a length of 2490 m, a width of 2490 m, and a height of 1010 m is established. Selecting 10 m as the unit size, the model is divided into 25,149 block units. For the 15,271 block units containing borehole data, the lithology codes (such as Abhg, λπa, etc.) are directly assigned to obtain the lithology block unit model. The remaining units are estimated by ordinary Kriging interpolation to obtain all the lithology block unit models of the mine.

[0102] Step 6. 21,614 core images are recorded on-site at the mine. The RQD recognition program is used to perform object detection on the core images, automatically crop the core area, and remove noise. Further, a semantic segmentation method is adopted to identify the effective area of the core.

[0103] Step 7. Based on the mapping relationship between RQD and fracture density, the fracture spacing is determined by fitting the probability density curve with a Gaussian distribution, and the RQD is converted to fracture density through the bisection method.

[0104] Step 8. The spatial layout data of the roadway and goaf in the mine engineering structure diagram are extracted through 3D modeling software. The roadway is simulated as a pipeline with a radius of 3 m to construct an intersecting and connected roadway model. The goaf is simulated as cuboids of different sizes to construct a goaf model. According to the three-dimensional coordinates, a Boolean union operation is performed on the roadway model and the goaf model to generate the void model of the complete mine.

[0105] Step 9. The in-situ stress test data measured at the mine are fitted. Through outlier screening and multiple linear regression analysis, a normal stress formula is constructed as shown in formula (5):

[0106] (5)

[0107] In the formula, H represents the depth, and P represents the normal stress.

[0108] Step 10. Using the established and divided three-dimensional block model, the fracture density, normal stress, lithology data, and void information are assigned to the left and right lithology block unit models, and ordinary Kriging interpolation is performed to construct a three-dimensional engineering geological characterization model considering in-situ stress, lithology, fracture characteristics, and void distribution.

[0109] Step 11. Set up a lithology-reference wave velocity table. Some of the preset contents in this embodiment are shown in Table 2, and the lithology codes of all units in the lithology block model are converted into the corresponding reference wave velocity values.

[0110] Table 2 Preset Lithology-Reference Wave Velocity Table of This Embodiment

[0111]

[0112] Step 12. Extract the geological feature data from the 3D engineering geological characterization model, traverse the fracture density and in-situ stress parameter values of all lithologic block unit models, use 45° as the global average fracture angle, and calculate the corrected wave velocity according to the preset wave velocity quantization formula (5). The corrected wave velocities at some positions in this embodiment are shown in Table 3.

[0113] Table 3 Corrected wave velocities at some positions in this embodiment

[0114]

[0115] Step 13. Read the goaf distribution information in the 3D engineering geological characterization model, overwrite the wave velocity of the goaf with the general atmospheric wave velocity of 340 m / s, and complete the construction of the 3D non-uniform wave velocity field of this mine.

[0116] The embodiments of the present invention are given for purposes of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are chosen and described in order to best explain the principles of the invention and its practical application, and to enable those of ordinary skill in the art to understand the invention so as to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for constructing a non-uniform wave velocity field model of an underground mine, characterized in that It includes the following steps: S1. Select a variety of rock materials, make multiple regular blocks, and measure the reference wave velocities of each of the regular blocks respectively; S2. Use the regular blocks to make rock specimens, conduct wave velocity test experiments on each of the rock specimens respectively, obtain experimental data, and construct a wave velocity quantization formula by fitting the experimental data; S3. Construct a three-dimensional block model of the prediction area according to the spatial characteristics of the prediction area, select the element size, divide the three-dimensional block model into multiple block element models according to the element size, and generate a lithology block element model by performing spatial interpolation on the block element models; S4. Based on the mapping relationship between the RQD value and the fracture density, the lithology data of the prediction area, the in-situ stress test data of the prediction area, the spatial characteristics of the prediction area, and the three-dimensional block model, construct a three-dimensional engineering geological characterization model; S5. Extract the geological feature data of the three-dimensional engineering geological characterization model, assign wave velocities to multiple lithology block element models based on the geological feature data using the wave velocity quantization formula, traverse all the lithology block element models, and obtain a three-dimensional non-uniform wave velocity field model; The step S2 includes the following steps: S201. Use the Brazilian splitting method to prefabricate different fracture densities and different fracture inclinations in multiple regular blocks respectively to obtain multiple rock specimens; S202. Place the rock specimens in a fixing device, conduct wave velocity test experiments on each of the rock specimens respectively under different normal stress conditions, and record the experimental data. The experimental data includes the wave velocity, the fracture density of the rock specimen, the normal stress received by the rock specimen, and the fracture inclination of the rock specimen. Among them, the fracture inclination is the included angle between the fracture and the normal stress; S203. Based on the experimental data, draw an experimental data curve, construct a fitting formula, and then construct the wave velocity quantization formula. The wave velocity quantization formula is shown in formula (1): （1） In the formula, v represents the wave velocity, v0 represents the reference wave velocity, m represents the fracture density of the rock specimen, p represents the normal stress received by the rock specimen, α represents the fracture inclination of the rock specimen, A represents the sine weight coefficient of the fracture inclination, B represents the cosine weight coefficient of the fracture inclination, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, E represents the comprehensive correction coefficient. Among them, the sine weight coefficient of the fracture inclination, the cosine weight coefficient of the fracture inclination, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data.

2. The method for constructing a non-uniform wave velocity field model of an underground mine according to claim 1, characterized in that, The step S3 includes the following steps: S301. Construct the three-dimensional block model according to the spatial characteristics of the prediction area; S302. Select the element size, and divide the three-dimensional block model into multiple block element models with the same size according to the spatial characteristics of the prediction area and the element size; S303. Based on the lithology data of the prediction area, perform spatial interpolation on each of the block element models respectively to generate multiple lithology block element models.

3. A method for constructing a non-uniform wave velocity field model of an underground mine according to claim 2, characterized in that, The spatial features of the prediction area in step S3 include: the geometric parameters of the prediction area, the three-dimensional layout of the void areas in the prediction area, the geometric parameters of the void areas in the prediction area, the number of drill holes in the prediction area, the volume of the drill holes in the prediction area, and the shape of the drill holes in the prediction area; Among them, the void areas in the prediction area include the roadways in the prediction area and the goafs in the prediction area.

4. A method for constructing a non-uniform wave velocity field model of an underground mine according to claim 1, characterized in that Step S4 includes the following steps: S401. Extract the three-dimensional layout and geometric parameters of the roadways in the prediction area based on the engineering structure diagram of the prediction area, simulate the roadways as pipelines, and construct an intersecting and connected roadway model; S402. Extract the three-dimensional layout of the goafs in the prediction area and the geometric parameters of the goafs in the prediction area based on the engineering structure diagram of the prediction area, simulate the goafs in the prediction area as cuboids of different sizes, and construct a goaf model; S403. Use the Boolean union operation to merge the roadway model and the goaf model to obtain the void area model of the prediction area, and obtain the void area information in the prediction area; S404. Based on the in-situ stress test data of the prediction area, construct an in-situ stress calculation formula through outlier screening and multiple linear regression analysis to obtain the in-situ stress of the prediction area; S405. Collect the cores of multiple prediction areas, take images of the cores, and obtain the RQD values of the cores; S406. Input the RQD values into the preset mapping relationship between the RQD values and the fracture density to obtain the fracture density; S407. Based on the void area information, the in-situ stress, the fracture density, and the lithology data of the prediction area of the prediction area, perform spatial interpolation on the lithology block unit model to construct the three-dimensional engineering geological characterization model.

5. A method for constructing a non-uniform wave velocity field model of an underground mine according to claim 4, characterized in that Step S405 includes the following steps: S415. Collect the cores of multiple prediction areas and take multiple images of the cores of the prediction areas; S425. Based on the OCR technology, respectively identify the identification information in each core image, generate a file containing the borehole number and the borehole depth, and uniformly name the file; S435. Analyze the core length of the borehole corresponding to the core image according to the naming of the file; S445. Automatically crop the effective area of the core through a target detection algorithm, identify the lithology name of the effective area, and mark the corresponding lithology code; S455. Use a semantic segmentation model to identify the length of the effective area and calculate the RQD value of the core.

6. The method for constructing a non-uniform wave velocity field model of an underground mine according to claim 5, wherein The lithology data of the prediction area includes: the borehole number, the borehole depth, the core length of the borehole, the lithology name, the lithology code, the length of the effective area, and the RQD value.

7. A method for constructing a non-uniform wave velocity field model of an underground mine according to claim 4, characterized in that, The preset mapping relationship between the RQD value and the fracture density in step S406 is shown in formula (2): （2） In the formula, n represents the fracture density; f(x) represents the fracture distribution function; x represents the fracture spacing; Among them, the fracture spacing is obtained by fitting the experimental data curve.

8. A method for constructing a non-uniform wave velocity field model of an underground mine according to claim 1, characterized in that, The step S5 includes the following steps: S501. Preset the mapping relationship between lithology data and reference wave velocity according to the various rock materials and the measured reference wave velocity; S502. Assign reference wave velocities to each of the lithology block unit models respectively according to the preset mapping relationship between lithology data and reference wave velocity, and traverse all the lithology block unit models to obtain a three-dimensional block reference wave velocity model; S503. Read the in-situ stress, the fracture density, the fracture dip angle in the prediction area in the three-dimensional engineering geological characterization model, and the goaf information in the prediction area; S504. Calculate the normal stress based on the in-situ stress in the prediction area; S505. Construct a wave velocity quantization formula for a non-uniform wave velocity field based on the wave velocity quantization formula, as shown in Formula (3): （3） In the formula, V represents the wave velocity of the non-uniform wave velocity field, v0 represents the reference wave velocity, n represents the fracture density, P represents the normal stress, β represents the fracture dip angle, A represents the sine weight coefficient of the fracture dip angle, B represents the cosine weight coefficient of the fracture dip angle, C represents the normal stress gain coefficient, D represents the fracture density attenuation coefficient, and E represents the comprehensive correction coefficient, where the sine weight coefficient of the fracture dip angle, the cosine weight coefficient of the fracture dip angle, the normal stress gain coefficient, the fracture density attenuation coefficient, and the comprehensive correction coefficient are constant coefficients obtained by fitting the experimental data; S506. Substitute the fracture density, the fracture dip angle, and the normal stress into the wave velocity quantization formula of the non-uniform wave velocity field to update the wave velocity of the three-dimensional block reference wave velocity model to obtain the three-dimensional non-uniform wave velocity field model, wherein, in combination with the goaf information in the prediction area, the wave velocity of the goaf is directly updated to the atmospheric wave velocity.

Images