An adaptive support method for surrounding rock in deep tunnels

Abstract

The present invention discloses an adaptive support method for deep tunnel surrounding rock, which relates to the technical field of tunnel surrounding rock monitoring and support. The method comprises: arranging a plurality of microseismic sensors in deep tunnels I and II in the upper and lower middle sections of a selected area, and determining that tunnel II surrounding rock needs to be strengthened with support; performing source excitation at arbitrary positions on both sides of I and II, and collecting microseismic signals with microseismic sensors; calculating the travel time of microseismic signals on different microseismic signal paths; constructing a three-dimensional model of the selected area and dividing the geological unit body, calculating the wave velocity of the geological unit body according to the coordinates of each source excitation position and microseismic sensor and the corresponding microseismic signal travel time, and thereby inverting the damage field of tunnel II surrounding rock; dividing the damage level of tunnel II surrounding rock, determining support parameters for different damage levels, and establishing a support plan corresponding to each damage level. The method has a better tunnel support effect, can reduce the tunnel support repair rate, and reduce the tunnel support cost.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel surrounding rock monitoring and support, and in particular to an adaptive support method for deep tunnel surrounding rock. Background Art

[0002] As mining continues to deepen, ground stress continues to increase, posing significant challenges to deep tunnel support. Frequent mining disturbances, especially under high-level stress, lead to severe instability in the surrounding rock of deep tunnels. Increased mining stress exacerbates surrounding rock fragmentation, causing large deformation and damage to the tunnel, severely impacting mine production safety. Currently, deep tunnel support generally adopts the traditional, experience-based, global support method. This method uses a unified support standard across all areas of the tunnel excavation face, referencing support parameters from mines with similar mining depths and rock quality. This method has numerous shortcomings in its application. The extent of surrounding rock damage and the risk of damage in deep tunnels are unclear. Support parameters are often determined empirically, using a unified support standard that lacks specificity. This leads to insufficient or excessive regional support strength, resulting in a high repair rate for tunnel support projects. This not only poses a serious threat to the safety of personnel and equipment, but also increases the economic cost of tunnel support. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide an adaptive support method for surrounding rock in deep tunnels.

[0004] The technical solution of the present invention is:

[0005] An adaptive support method for surrounding rock of a deep tunnel, the method comprising the following steps:

[0006] Step 1: Select an area close to the deep stope, deploy multiple microseismic sensors in deep tunnels I and II in the upper and lower middle sections of the area, and determine that deep tunnel II requires enhanced support.

[0007] Step 2: performing source excitation at any position on both sides of deep tunnels I and II, and collecting microseismic signals through the microseismic sensors;

[0008] Step 3: Subtract the corresponding source excitation time from the time when each microseismic sensor receives the microseismic signal to obtain the microseismic signal travel time on different microseismic signal paths;

[0009] Step 4: Using 3D geological tomography technology, a 3D model is constructed for the area selected in step 1 and the area is divided into geological units. The wave velocity of the geological units is calculated based on the coordinates of each source excitation position, the coordinates of each microseismic sensor, and the corresponding microseismic signal travel time.

[0010] Step 5: Invert the damage field of the surrounding rock of deep tunnel II based on the wave velocity of the geological unit volume;

[0011] Step 6: Based on the damage field of the surrounding rock of deep tunnel II, the damage level of the surrounding rock of deep tunnel II is divided, the support parameters of the surrounding rock of deep tunnel II with different damage levels are determined, and a support scheme corresponding to each damage level of the surrounding rock of deep tunnel II is established.

[0012] Furthermore, the microseismic sensors are all connected to the existing microseismic monitoring system of the mine.

[0013] Furthermore, all microseismic sensors are of the same model and are arranged in parallel at equal distances, and the straight-line distance between any two microseismic sensors does not exceed the effective monitoring range of the microseismic sensor of that model.

[0014] Furthermore, the microseismic sensor is a unidirectional microseismic sensor.

[0015] Furthermore, a CD-2 portable electric spark source was used for source excitation.

[0016] Furthermore, according to the coordinates of each source excitation position, the coordinates of each microseismic sensor and the corresponding microseismic signal travel time, the linear travel time interpolation path tracing algorithm and the back projection iterative algorithm are used to calculate the wave velocity of the geological unit volume.

[0017] Furthermore, step 5 includes: calculating the damage degree of the geological unit bodies on all microseismic signal paths based on the wave velocity of each geological unit body; interpolating the damage degree of the geological unit bodies around the deep tunnel Ⅱ4 to obtain the three-dimensional surrounding rock damage field of the deep tunnel Ⅱ4; using the interpolation results, making a contour map of the surrounding rock damage degree on the side of the deep tunnel Ⅱ4 close to the deep mining area.

[0018] Furthermore, the method for dividing the damage level of the surrounding rock of the deep tunnel II4 described in step 6 is: based on the surrounding rock damage field of the deep tunnel II4, the surrounding rock damage degree D is divided into four value ranges, and the four value ranges correspond to the four damage levels of the surrounding rock of the deep tunnel II: level I - slight damage, level II - mild damage, level III - moderate damage, and level IV - severe damage.

[0019] Furthermore, the support parameters described in step 6 include support strength and support depth; the method for solving the support depth of different damage levels is: first determine the surrounding rock damage depth based on the contour map of the surrounding rock damage degree on the side of deep tunnel Ⅱ4 close to the deep mining area, and then add the surrounding rock damage depth and the length of the anchor rod anchored in the original rock.

[0020] Furthermore, the method for determining the surrounding rock damage depth based on the contour map of the surrounding rock damage degree on the side of the deep tunnel II4 close to the deep stope is: selecting the surrounding rock damage depth corresponding to the minimum value of the surrounding rock damage degree in the longitudinal direction of the contour map to obtain the surrounding rock damage depth.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention performs source excitation in a deep tunnel and arranges multiple microseismic sensors to collect microseismic signals, and then combines them with three-dimensional geological tomography technology to invert the deep tunnel surrounding rock damage field. The damage field is a large-scale three-dimensional damage field covering the entire middle section height, which can reflect the degree of rock damage in the entire middle section. It not only provides a reference basis for the selection of support methods for the current deep tunnel, but also provides a design reference for the support of new deep tunnels excavated in the middle section. Moreover, through the deep tunnel surrounding rock damage field, the distribution of high-risk areas of rock instability can be intuitively seen, overcoming the disadvantage of the traditional empirical method of surrounding rock damage risk.

[0023] (2) The present invention establishes an adaptive support technology that provides low-intensity support in slightly damaged areas and high-intensity support in severely damaged areas. Compared with the traditional full-area support method, the technology is more targeted and avoids the problem of personnel and equipment safety being threatened and support costs being increased due to the support strength being too weak or too strong in a local area. At the same time, the support parameters of the adaptive support technology are theoretically calculated based on the surrounding rock damage depth and damage degree, which has a better tunnel support effect, reduces the tunnel support repair rate, and reduces the deep tunnel support cost.

[0024] (3) In the context of deep mining, deep underground mines usually use real-time online ground pressure monitoring systems, namely microseismic monitoring systems, to prevent and control the potential safety hazards of ground pressure in deep mining. The present invention makes full use of the existing microseismic monitoring system of the mine to collect and analyze the microseismic signals collected by the microseismic sensors, greatly reducing the implementation cost of the present invention. In addition, the arranged unidirectional microseismic sensor group can still be used for deep ground pressure monitoring in the future, preventing the potential safety hazards of ground pressure in deep mining, and improving the utilization rate of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Flowchart of the adaptive support method for surrounding rock of deep tunnel in this embodiment;

[0026] Figure 2 This is a structural diagram of the mine microseismic monitoring system;

[0027] Figure 3 Schematic diagram of the deep tunnel position in this embodiment;

[0028] Figure 4 Schematic diagrams of the arrangement of microseismic sensors on deep tunnels according to this embodiment, wherein (a) is a schematic diagram of the arrangement of microseismic sensors on deep tunnel I; (b) is a schematic diagram of the arrangement of microseismic sensors on deep tunnel II;

[0029] Figure 5 Schematic diagram of the location of the seismic source excitation holes in this embodiment, wherein (a) is a schematic diagram of the location of the seismic source excitation holes on deep tunnel I; (b) is a schematic diagram of the location of the seismic source excitation holes on deep tunnel II;

[0030] Figure 6 This is a schematic diagram of the principle of three-dimensional geological tomography technology;

[0031] Figure 7 This is a contour map of the surrounding rock damage degree on the side of deep tunnel II close to the deep stope in this implementation method.

[0032] The accompanying drawings illustrate:

[0033] 1—deep stope; 101—the first one-way microseismic sensor of the first group; 102—the second one-way microseismic sensor of the first group; 103—the third one-way microseismic sensor of the first group; 104—the fourth one-way microseismic sensor of the first group; 105—the fifth one-way microseismic sensor of the first group; 106—the sixth one-way microseismic sensor of the first group; 2—ore body; 201—the first one-way microseismic sensor of the second group; 202—the second one-way microseismic sensor of the second group; 203—the third one-way microseismic sensor of the second group; 204—the fourth one-way microseismic sensor of the second group Four unidirectional microseismic sensors; 205—the fifth unidirectional microseismic sensor of the second group; 206—the sixth unidirectional microseismic sensor of the second group; 3—deep tunnel I; 4—deep tunnel II; 5—deep tunnel I section; 501—the first seismic source excitation hole of tunnel I section; 502—the second seismic source excitation hole of tunnel I section; 6—deep tunnel II section; 601—the first seismic source excitation hole of tunnel II section; 602—the second seismic source excitation hole of tunnel II section; 603—the third seismic source excitation hole of tunnel II section; 604—the fourth seismic source excitation hole of tunnel II section. DETAILED DESCRIPTION

[0034] To facilitate understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings.

[0035] Figure 1 This is a flow chart of the adaptive support method for surrounding rock in deep tunnels according to this embodiment. Figure 1 As shown, the adaptive support method for surrounding rock of deep tunnels includes the following steps:

[0036] Step 1: Select an area close to the stope, deploy multiple microseismic sensors in deep tunnels I and II in the upper and lower middle sections of the area, and determine that the surrounding rock of deep tunnel II requires enhanced support; all of the microseismic sensors are connected to the mine's existing microseismic monitoring system;

[0037] The existing microseismic monitoring system is as follows Figure 2As shown, it includes microseismic sensors, data acquisition instruments, data transmission substations, data servers, and timing servers; the microseismic sensors include one-way microseismic sensors and three-way microseismic sensors; the data server is equipped with real-time microseismic wave display software and microseismic signal automatic collection and analysis software.

[0038] The operation process of the microseismic monitoring system is as follows: first, the timing server synchronizes the time of the one-way microseismic sensors and three-way microseismic sensors in the entire well to ensure the accuracy of the spatial location of the subsequent rock fracture. Then, the microseismic sensors collect the microseismic signals generated by the rock fracture and transmit the microseismic signals to the data acquisition instrument via cable. Then, the microseismic signals of all data acquisition instruments are transmitted via cable to the data transmission substation. The data transmission substation transmits the microseismic signals from the well to the surface data server via optical fiber. Finally, the microseismic signal automatic collection and analysis software in the data server records the moment when the microseismic signal is received by the microseismic sensor (hereinafter referred to as the arrival time of the microseismic signal) and calculates the spatial position of the rock fracture and the amount of released energy. It should be noted that the existing microseismic monitoring system may contain multiple data acquisition instruments, and Figure 1 In the microseismic monitoring system structure shown, only one data acquisition instrument is drawn for illustration.

[0039] In this embodiment, an area close to the deep stope 1 is selected according to the mining progress. Furthermore, a deep tunnel is selected at each of the upper and lower middle levels of the area. Figure 3 As shown in FIG, deep tunnels I3 and II4 on the left side of the stope are selected. Both deep tunnels I3 and II4 are arranged along the strike of ore body 2, of which deep tunnel II4 needs to be strengthened with support. A set of one-way microseismic sensors is arranged in each of the two deep tunnels. The model of the one-way microseismic sensor is consistent with the model used in the existing microseismic monitoring system. It follows the principles of wide coverage, priority for key areas, and uniform spatial distribution. The one-way microseismic sensors on both sides of the deep tunnel I3 in the upper middle section are arranged equidistantly and in parallel, and the one-way microseismic sensors on both sides of the deep tunnel II4 in the lower middle section are also arranged equidistantly and in parallel. Moreover, the straight-line distance between any two one-way microseismic sensors at the upper and lower middle sections does not exceed the effective monitoring range of the one-way microseismic sensor of this model. Taking the middle section height of 50m and the effective monitoring range of the one-way microseismic sensor of 150m as an example, the specific arrangement is as follows: Figure 4 (a) and (b) show:

[0040] First, the first group of unidirectional microseismic sensors, totaling 6 unidirectional microseismic sensors, was deployed in the deep tunnel I3 of the upper middle section. The first group of first unidirectional microseismic sensors 101 and the second group of first unidirectional microseismic sensors 102 were deployed in the tunnel section 5 m behind the deep stope 1. The first group of third unidirectional microseismic sensors 103 and the first group of fourth unidirectional microseismic sensors 104 were deployed in the tunnel section 65 m behind the deep stope 1. The first group of fifth unidirectional microseismic sensors 105 and the first group of sixth unidirectional microseismic sensors 106 were deployed in the tunnel section 125 m behind the deep stope 1.

[0041] Then, a second group of unidirectional microseismic sensors, totaling 6 unidirectional microseismic sensors, was arranged in the deep roadway II4 of the lower middle section. The first unidirectional microseismic sensor 201 of the second group and the second unidirectional microseismic sensor 202 of the second group were arranged in the roadway section 5 m behind the deep stope 1. The third unidirectional microseismic sensor 203 of the second group and the fourth unidirectional microseismic sensor 204 of the second group were arranged in the roadway section 65 m behind the deep stope 1. The fifth unidirectional microseismic sensor 205 of the second group and the sixth unidirectional microseismic sensor 206 of the second group were arranged in the roadway section 125 m behind the deep stope 1.

[0042] The installation procedures for the first and second sets of unidirectional microseismic sensors are the same. Each unidirectional microseismic sensor is located at the aforementioned cross-section, 0.5 m above the tunnel floor, and drilled 8 m long holes perpendicular to the tunnel sidewall at a 5° downward inclination, passing through the loosened rock zone. After drilling, the rock debris and water in the holes are cleaned out, and the unidirectional microseismic sensors are lowered along the hole wall to the bottom. The holes are then sealed with concrete grouting, and the spatial coordinates of all unidirectional microseismic sensors are recorded.

[0043] Furthermore, the first group of six unidirectional microseismic sensors are connected to the data acquisition device D1, and the second group of six unidirectional microseismic sensors are connected to the data acquisition device D2. Both the data acquisition device D1 and the data acquisition device D2 are connected to the data transmission substation of the existing microseismic monitoring system to realize automatic collection and analysis of microseismic signals.

[0044] Step 2: Excite the source at any position on both sides of deep tunnels I and II, and collect microseismic signals through unidirectional microseismic sensors arranged in the two tunnels;

[0045] In this embodiment, a CD-2 portable spark source is used to perform source excitation at any position on both sides of deep tunnel I3 and deep tunnel II4. The CD-2 portable spark source mainly includes: a main unit, a capacitor, a high-energy discharger, a discharge probe (including a 60-meter cable), an inverter, a synchronous trigger, a high-voltage voltmeter, a wireless remote control, and supporting connecting cables;

[0046] The source excitation process of deep tunnel Ⅰ3 is as follows:

[0047] First, use a network cable to connect the data acquisition instrument D1 to the host of the CD-2 portable electric spark source, and then connect the host to the timing server through the local area network to ensure that the host of the CD-2 portable electric spark source and all unidirectional microseismic sensors maintain time synchronization;

[0048] Then, a hole is drilled at the section 5 of the deep tunnel I where the first one-way microseismic sensor 101 of the first group and the second one-way microseismic sensor 102 of the first group are located, which is called a source excitation hole. Figure 5 (a) shows two seismic source excitation holes in the tunnel section 5 at depth, one on either side of the section, 1 m above the tunnel floor. A handheld percussion drill was used to drill two seismic source excitation holes, first perpendicular to the tunnel wall and then inclined downward 50°. These holes are the first seismic source excitation hole 501 and the second seismic source excitation hole 502 in tunnel section 1. The diameter of each hole is slightly larger than the diameter of the discharge probe, and the length of each hole is approximately 5 cm longer than the discharge probe. After drilling, the rock debris in the hole was cleaned, and the spatial coordinates of each seismic source excitation hole were recorded.

[0049] Then, discharge probes are sequentially placed into the first seismic source excitation hole 501 and the second seismic source excitation hole 502 of the tunnel section I, and water is added into the holes to cover the discharge probes. Finally, a wireless remote control is used to control the seismic source to excite one by one, and the seismic source excitation time of each seismic source excitation hole is recorded respectively. The first group of unidirectional microseismic sensors and the second group of unidirectional microseismic sensors are used to collect microseismic signals. The microseismic signal automatic collection and analysis software of the existing microseismic monitoring system is used to record the arrival time of multiple microseismic signals generated by each seismic source excitation. If five unidirectional microseismic sensors receive the signals when the seismic source is excited once, then the arrival time of five microseismic signals generated by this seismic source excitation is recorded.

[0050] According to the above operation, in the direction away from the deep stope 1, source excitation holes are drilled every 1 m in the roadway section until the roadway section where the fifth unidirectional microseismic sensor 105 of the first group and the sixth unidirectional microseismic sensor 106 of the first group are located is reached. The location and number of holes drilled in each roadway section are the same as above. After the drilling is completed, the source is excited one by one, and the spatial coordinates and source excitation time of each source excitation hole are recorded, as well as the arrival time of multiple microseismic signals generated by each source excitation.

[0051] The source excitation process of deep tunnel II4 is as follows:

[0052] First, use a network cable to connect the data acquisition instrument D2 to the host computer, and then connect the host computer to the timing server through the local area network, so that the host computer of the CD-2 portable electric spark source and all unidirectional microseismic sensors maintain time synchronization;

[0053] Then, a source excitation hole is drilled at the section 6 of the deep tunnel II where the first one-way microseismic sensor 201 of the second group and the second one-way microseismic sensor 202 of the second group are located. Figure 5 As shown in (b), there are 4 seismic source excitation holes in the section, one on each side of the tunnel section, 1m and 2m above the tunnel floor. A handheld impact drill is used to drill the 4 seismic source excitation holes perpendicular to the tunnel wall and then inclined downward by 50°. These are the first seismic source excitation hole 601 in the tunnel II section, the second seismic source excitation hole 602 in the tunnel II section, the third seismic source excitation hole 603 in the tunnel II section, and the fourth seismic source excitation hole 604 in the tunnel II section. The hole diameters are slightly larger than the discharge probe diameter, and the hole lengths are about 5cm longer than the discharge probe. After drilling is completed, the rock debris in the hole is cleaned and the spatial coordinates of each seismic source excitation hole are recorded.

[0054] Then, the discharge probes are sequentially placed into the first seismic source excitation hole 601, the second seismic source excitation hole 602, the third seismic source excitation hole 603, and the fourth seismic source excitation hole 604 of the tunnel II section. Water is added into the holes to cover the discharge probes. Finally, a wireless remote control is used to control the source excitation, and the source excitation time of each seismic source excitation hole is recorded. Microseismic signals are collected by the first group of unidirectional microseismic sensors and the second group of unidirectional microseismic sensors. The arrival time of multiple microseismic signals generated by each source excitation is recorded by the microseismic signal automatic collection and analysis software of the existing microseismic monitoring system.

[0055] According to the above operation, a source excitation hole is drilled in the tunnel section every 1 m in the direction away from the deep mining area 1 until the tunnel section where the fifth unidirectional microseismic sensor 205 of the second group and the sixth unidirectional microseismic sensor 206 of the second group are located is reached. The position and number of each drill hole in the tunnel section are the same as above. After the drilling is completed, the source is excited one by one, and the spatial coordinates and source excitation time of each source excitation hole are recorded, as well as the arrival time of multiple microseismic signals generated by each source excitation.

[0056] Step 3: Subtract the corresponding source excitation time from the time when each unidirectional microseismic sensor receives the microseismic signal collected by the microseismic monitoring system to obtain the microseismic signal travel time on different microseismic signal paths;

[0057] As known to those skilled in the art, the time difference between the excitation of the earthquake source and the reception of the microseismic sensor is called the microseismic signal travel time.

[0058] Step 4: Using 3D geological tomography technology, a 3D model is constructed for the area selected in step 1 and the area is divided into geological units. The wave velocity of the geological units is calculated based on the coordinates of each source excitation position, the coordinates of each unidirectional microseismic sensor, and the corresponding microseismic signal travel time.

[0059] The principle of 3D geological tomography technology is as follows Figure 6 As shown, this embodiment first constructs a three-dimensional model of the area selected in step 1, and divides the constructed three-dimensional model into geological regional grids in Matlab to obtain individual geological unit bodies. The wave velocity of the geological unit body on the microseismic signal path can be calculated based on the known source coordinates, microseismic sensor coordinates and the microseismic signal travel time on each microseismic signal path. Each geological unit body is regarded as an isotropic medium, and the P wave, that is, the wave velocity of the microseismic signal in the geological unit body, is an unknown quantity. The P wave velocity of different geological units is different. The more microseismic signal travel times there are, the more accurate the wave velocity calculation of the geological unit body is.

[0060] In this embodiment, Matlab is first used to establish a three-dimensional cuboid model with a length, width, and height of 150 m, 20 m, and 55 m, respectively, so that the model covers the spatial coordinates of the following eight unidirectional microseismic sensors: the first unidirectional microseismic sensor 101 of the first group, the second unidirectional microseismic sensor 102 of the first group, the fifth unidirectional microseismic sensor 105 of the first group, the sixth unidirectional microseismic sensor 106 of the first group, the first unidirectional microseismic sensor 201 of the second group, the second unidirectional microseismic sensor 202 of the second group, the fifth unidirectional microseismic sensor 205 of the second group, and the sixth unidirectional microseismic sensor 206 of the second group. Based on experience and experimental results, a cube with a side length of 1 m is determined as a geological unit volume, and the three-dimensional cuboid model is meshed to obtain individual geological units.

[0061] Based on the above three-dimensional model, the linear travel time interpolation path tracing algorithm is used to input the coordinates of the source excitation hole and the one-way microseismic sensor of the i-th microseismic signal to calculate the propagation path of the i-th microseismic signal in the rectangular three-dimensional model. As shown in formula (1);

[0062]

[0063] Where a ij is the propagation distance of the i-th microseismic signal in the j-th geological unit; J is the total number of geological units in the rectangular 3D model, j = 1, 2, ..., J, J = 150 * 20 * 55;

[0064] In this way, the propagation paths of all I microseismic signals are calculated to obtain the coefficient matrix A, as shown in formula (2);

[0065]

[0066] Where I represents the total number of microseismic signals received by the one-way microseismic sensor;

[0067] Through step 2, we can know the time of each source excitation and the corresponding microseismic signal arrival time, and calculate the time difference between all I microseismic signals from the source excitation to the one-way microseismic sensor reception As shown in formula (3);

[0068]

[0069] The travel time of the i-th microseismic signal is T i , i≤I, its mathematical expression is as follows:

[0070]

[0071] Where j = 1, 2, ..., J, J = 150 * 20 * 55; s j is the slowness of the j-th geological unit, i.e. the inverse of the P-wave velocity;

[0072] Substituting all the microseismic signals collected by the unidirectional microseismic sensor, i.e., I microseismic signals, into formula (4), we obtain the following equation group (5):

[0073]

[0074] The matrix expression of equation group (5) is:

[0075]

[0076] From formula (2) and formula (3), we can know that A and is the known quantity calculated, which is substituted into formula (6) and the back-projection iterative algorithm based on MATLAB is used to calculate It is the inverse of the wave velocity of the geological unit on all microseismic signal paths. The expression is as follows:

[0077]

[0078] Take the inverse of formula (7) to calculate the wave velocity of the geological unit on all microseismic signal paths: The expression is as follows;

[0079]

[0080] Step 5: Invert the damage field of the surrounding rock of deep tunnel II based on the wave velocity of the geological unit volume;

[0081] Substitute formula (8) into the rock damage formula (9) to calculate the damage degree of the geological unit body on all microseismic signal paths: The expression of is shown in formula (10);

[0082]

[0083] Where v is the P-wave velocity of the geological unit; v0 is the P-wave velocity of the intact rock block, which is obtained by sampling the surrounding rock of the roadway and performing P-wave testing using an HF-D ultrasonic instrument;

[0084]

[0085] According to formula (10), the damage degree of the geological unit body on all microseismic signal paths can be obtained. It is imported into the Surfer software, and the damage degree D of the geological unit body around the deep tunnel Ⅱ4 is interpolated to obtain the three-dimensional surrounding rock damage field of the deep tunnel Ⅱ4.

[0086] Considering that the surrounding rock damage on the side of deep tunnel Ⅱ4 close to deep stope 1 is more serious, the support parameter design is based on this, and a contour map of the surrounding rock damage degree on the north side of deep tunnel Ⅱ4 is made, as shown in the figure below. Figure 7 As shown in the figure, the closer to the mining area, the more serious the damage to the surrounding rock of the roadway. In the vertical direction, the damage value is larger near the roadway wall, and as the depth of the surrounding rock increases, the surrounding rock damage value first decreases and then increases.

[0087] Step 6: Based on the damage field of the surrounding rock of deep tunnel II, the damage level of the surrounding rock of deep tunnel II is divided, the support parameters of the surrounding rock of deep tunnel II with different damage levels are determined, and a support scheme corresponding to each damage level of the surrounding rock of deep tunnel II is established.

[0088] This implementation method is based on the surrounding rock damage field of deep tunnel II4 and divides the surrounding rock damage degree D into four value ranges, corresponding to four surrounding rock damage levels: level I (slight damage), level II (mild damage), level III (moderate damage), and level IV (severe damage), with the damage degree increasing in sequence.

[0089] According to different surrounding rock damage levels, on the one hand, the support strength is determined, and support forms of different strengths are selected by referring to the mining engineering design manual; on the other hand, the support depth is determined, and the surrounding rock damage depth L is determined based on the contour map of the surrounding rock damage degree on the side of deep tunnel II4 close to deep stope 1. D , the calculation formula of support depth L is as follows:

[0090] L=L D +L0

[0091] Where, L D is the depth of surrounding rock damage; L0 is the length of the anchor bolt anchored in the original rock, generally taken as 0.3m;

[0092] The surrounding rock damage depth L is determined based on the contour map of the surrounding rock damage degree on the side of the deep tunnel II4 close to the deep stope 1. D , specifically:

[0093] At a certain position away from the deep stope 1, in the vertical direction of the contour map, as the surrounding rock depth increases, the surrounding rock damage degree D shows a trend of first decreasing and then increasing. The surrounding rock damage depth corresponding to the minimum value of the surrounding rock damage degree D in the vertical direction is selected to obtain the surrounding rock damage depth L. D ;

[0094] Since Grade I surrounding rock damage is considered slight and does not require anchor support, it is only necessary to calculate the maximum support depths for Grade II, III, and IV surrounding rock damage and establish adaptive support schemes for different surrounding rock damage levels, as shown in Table 1.

[0095] Table 1 Adaptive support schemes for different surrounding rock damage levels

[0096]

[0097]

[0098] It should be understood that, inspired by the technical concept of the present invention, those skilled in the art may make various improvements or changes based on the above content without departing from the content of the present invention, which still fall within the scope of protection of the present invention.

Claims

1. An adaptive support method for surrounding rock in deep tunnels, characterized in that: The method comprises the following steps: Step 1: Select an area close to the deep stope, deploy multiple microseismic sensors in deep tunnels I and II in the upper and lower middle sections of the area, and determine that the surrounding rock of deep tunnel II needs to be strengthened. Step 2: performing source excitation at any position on both sides of deep tunnels I and II, and collecting microseismic signals through the microseismic sensors; Step 3: Subtract the corresponding source excitation time from the time when each microseismic sensor receives the microseismic signal to obtain the microseismic signal travel time on different microseismic signal paths; Step 4: Use 3D geological tomography technology to construct a 3D model of the area selected in step 1 and divide it into geological units. Then calculate the wave velocity of the geological unit based on the coordinates of each source excitation position, the coordinates of each microseismic sensor and the corresponding microseismic signal travel time. , The expression is as follows: (8) Step 5: Invert the damage field of the surrounding rock of deep tunnel II based on the wave velocity of the geological unit volume; Substitute formula (8) into the rock damage formula (9) to calculate the damage degree of the geological unit body on all microseismic signal paths: , The expression of is shown in formula (10); (9) Where, v is the P-wave velocity of the geological unit; v 0 The P-wave velocity of the intact rock mass is obtained by sampling the surrounding rock of the roadway and performing P-wave testing using an HF-D ultrasonic instrument. (10) According to formula (10), the damage degree of the geological unit body on all microseismic signal paths can be obtained. It is imported into the Surfer software, and the damage degree D of the geological unit body around the deep tunnel Ⅱ4 is interpolated to obtain the three-dimensional surrounding rock damage field of the deep tunnel Ⅱ4. Step 6: Based on the damage field of the surrounding rock of deep tunnel II, the damage level of the surrounding rock of deep tunnel II is divided, the support parameters of the surrounding rock of deep tunnel II with different damage levels are determined, and a support scheme corresponding to each damage level of the surrounding rock of deep tunnel II is established.

2. The method according to claim 1, wherein The microseismic sensors are all connected to the existing microseismic monitoring system of the mine.

3. The method according to claim 1, wherein All microseismic sensors are of the same model and are arranged in parallel at equal distances, and the straight-line distance between any two microseismic sensors does not exceed the effective monitoring range of the microseismic sensor of that model.

4. The method according to claim 1, 2 or 3, wherein: The microseismic sensor is a unidirectional microseismic sensor.

5. The method according to claim 1, wherein A CD-2 portable electric spark vibrator was used for source excitation.

6. The method according to claim 1, wherein According to the coordinates of each source excitation position, the coordinates of each microseismic sensor and the corresponding microseismic signal travel time, the linear travel time interpolation path tracing algorithm and the back projection iterative algorithm are used to calculate the wave velocity of the geological unit volume.

7. The method according to claim 1, wherein Step 5 includes: calculating the damage degree of the geological units on all microseismic signal paths based on the wave velocity of each geological unit; interpolating the damage degree of the geological units around the deep tunnel II to obtain the three-dimensional surrounding rock damage field of the deep tunnel II; and using the interpolation results to make a contour map of the surrounding rock damage degree on the side of the deep tunnel II close to the deep stope.

8. The method according to claim 7, wherein The method for dividing the damage level of the surrounding rock of deep tunnel II described in step 6 is: based on the surrounding rock damage field of deep tunnel II, the surrounding rock damage degree D is divided into four value ranges, and the four value ranges correspond to the four damage levels of the surrounding rock of deep tunnel II: level I - slight damage, level II - mild damage, level III - moderate damage, and level IV - severe damage.

9. The method according to claim 8, wherein The support parameters described in step 6 include support strength and support depth; the method for solving the support depth of different damage levels is: first, determine the surrounding rock damage depth based on the contour map of the surrounding rock damage degree on the side of deep tunnel II close to the deep mining area, and then add the surrounding rock damage depth and the length of the anchor rod anchored in the original rock.

10. The method according to claim 9, wherein The method for determining the surrounding rock damage depth based on the contour map of the surrounding rock damage degree on the side of the deep tunnel II close to the deep stope is: selecting the surrounding rock damage depth corresponding to the minimum value of the surrounding rock damage degree in the longitudinal direction of the contour map to obtain the surrounding rock damage depth.

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