Rock burst roadway heading coal body blasting side prevention method

Abstract

The present application relates to roadway construction method technical field, especially to a kind of rock burst roadway head-on coal body blasting side prevention and control method, and the prevention and control method includes the following steps: to the site roadway head-on ground stress test;Collect the coal sample of roadway head-on roadway side coal body and make sample, stress loading is carried out to sample, determine reasonable drilling diameter;Obtain multiple samples and carry out drilling grouting test;To the site roadway head-on advance drilling construction, to form advance drilling on roadway side coal body, to advance drilling with water jet, to form jet hole in roadway side coal body;To the jet hole formed is modified by grouting.The present application effectively controls the problems such as roadway heading process roadway side coal body blasting, slice and deformation, improves the poor problem of roadway side coal body forming, reduces the impact tendency of coal body, improves the integrity and strength of roadway side coal body.

Description

Technical Field

[0001] This invention relates to the technical field of roadway construction methods, and in particular to a method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst. Background Technology

[0002] Rockbursts are one of the major disasters facing coal mines worldwide. When a rockburst occurs, the coal and rock mass around the mine roadways and working face suffers huge losses of personnel and equipment due to the instantaneous release of elastic energy.

[0003] In typical mining areas with rockburst-prone coal bodies, such as Binchang and Xinjiang, the coal bodies in rockburst roadways are characterized by high strength, brittleness, and highly developed vertical fractures. Jointed and fractured coal bodies exhibit a strong rockburst tendency. Therefore, during roadway excavation, the coal seams in the roadway sides are prone to problems such as rockburst and spalling, affecting worker safety and normal production. Furthermore, the rockburst and spalling problems in the roadway sides result in poor coal seam formation, unevenness, and difficulty in effectively supporting the coal seams. Roadway mesh laying is difficult, and anchor bolts and anchor cable plates are not easily fitted tightly to the coal seams during support, leading to poor anchor bolt support effectiveness. Moreover, the coal seams in the roadway sides deform significantly during the face recovery process. In conclusion, the prevention and control of rockburst and spalling in the coal seams during roadway excavation is a crucial issue that urgently needs to be addressed in the industry. Summary of the Invention

[0004] This invention provides a method for preventing and controlling coal face blasting in roadways prone to rockbursts, which is used to control the problems of coal face blasting and spalling during roadway excavation and improve the problem of poor coal face formation.

[0005] This invention provides a method for preventing coal face blasting in roadways prone to rockbursts, comprising the following steps:

[0006] Step 1: Conduct ground stress testing at the face of the roadway.

[0007] Step 2: Collect coal samples from the coal seam at the face of the roadway and prepare them into test specimens. Apply stress to the test specimens and analyze the impact failure law of the test specimens under stress loading.

[0008] Step 3: Take multiple specimens prepared in Step 2 and conduct drilling tests on them. Arrange a predetermined number of holes in each specimen. The diameters of the holes between the specimens are different. After drilling, stress is applied to the specimens. Analyze the effect of different hole diameters on the impact failure of the specimens under stress loading and determine a reasonable hole diameter.

[0009] Step 4: Based on the borehole diameter determined in Step 3, take multiple samples obtained in Step 2 and conduct borehole grouting tests.

[0010] Step 5: Conduct advanced drilling at the face of the roadway to form advanced boreholes in the coal seam of the roadway side, and perform water jetting on the advanced boreholes to form jet holes in the coal seam of the roadway side.

[0011] Step 6: Based on the test results in Step 4, the jet holes formed in Step 5 are modified by grouting.

[0012] According to the method for preventing and controlling rockburst in roadway face coal seam provided by the present invention, based on the borehole diameter of the test in step three and the analysis of the field inspection results in step five, reasonable water jet process parameters are determined. The water jet process parameters include jet pressure and jet orifice diameter. The specific value of the jet pressure is determined according to the strength of the roadway face coal seam, and the diameter of the jet orifice is determined according to the borehole diameter determined in step three.

[0013] According to the method for preventing and controlling rockburst at the face of coal seam in roadways provided by the present invention, in step five, water jets are performed intermittently from the inside to the outside along the length direction of the advance borehole.

[0014] According to the method for preventing and controlling rockburst in roadway face coal seam provided by the present invention, the length of the advance borehole is 20m to 30m, and the jet pressure is 20MPa to 50MPa.

[0015] The interval between the centers of two adjacent jet holes is 1.5m to 2.5m.

[0016] According to the method for preventing and controlling coal seam blasting at the face of a roadway provided by the present invention, in step six, the jet holes are grouted from the inside out along the length direction of the advanced borehole, with the grouting area interval being 1.5m to 2.5m.

[0017] According to the rockburst roadway face coal seam blasting prevention and control method provided by the present invention, in step six, based on the test results in step four and the analysis of the field inspection results, reasonable grouting materials and grouting process parameters are determined, wherein the grouting process parameters include grouting volume and grouting pressure.

[0018] According to the method for preventing and controlling rockburst at the face of coal seam in roadways provided by the present invention, in step six, the grouting volume is not less than 2t and the grouting pressure ranges from 5MPa to 20MPa.

[0019] The method for preventing rockburst-induced coal seam blasting at the face of a roadway according to the present invention further includes:

[0020] Step 7: Deploy monitoring equipment to monitor impact events in the coal seam along the roadway during tunnel excavation and acquire monitoring data. Analyze the monitoring data and determine whether to adjust and optimize the water jet process parameters, grouting materials, and grouting process parameters.

[0021] According to the method for preventing and controlling rockburst-induced coal blasting at the face of a roadway provided by the present invention, in step one, a hydraulic fracturing method is used to conduct in-situ stress testing on the roadway coal face to investigate the stress state at the face of the roadway and obtain the magnitude and direction of the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress of the roadway coal face.

[0022] According to the method for preventing and controlling rockburst at the face of coal seam in roadways provided by the present invention, in step two, the length of the sample is a, where a is 30mm to 70mm, the width of the sample is b, where b is 30mm to 70mm, and the height of the sample is c, where c is 80mm to 120mm; in step three, a hole is drilled along the middle of the side of the sample, with one hole for each sample, and the diameter of the hole for the sample is in the range of 4mm to 10mm.

[0023] The present invention provides a method for preventing coal face blasting in roadways prone to rock bursts. Step one optimizes the roadway excavation direction to reduce the intensity of blasting during excavation. Steps two through four then determine a preliminary reasonable borehole diameter based on experimental results and conduct grouting tests. Step five involves creating jet cavities in the coal face to reduce stress concentration and elasticity, thereby lowering the impact tendency and intensity of the coal face during excavation. After step five, the jet cavities are modified with grout, utilizing the bonding properties of the grouting material to prevent coal face spalling and collapse during excavation. This method effectively controls coal face blasting, spalling, and deformation during roadway excavation, improves the poor coal face formation, reduces the impact tendency of the coal, and enhances the integrity and strength of the coal face. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the roadway construction design in the method for preventing and controlling rockburst in roadways provided by the present invention, wherein the jet holes are not grouted by the grouting sealing device;

[0026] Figure 2 yes Figure 1 Enlarged schematic diagram of the structure at point A;

[0027] Figure 3This is a schematic diagram of the roadway construction design in the method for preventing and controlling rockburst in roadways provided by the present invention, wherein the jet holes are grouted by a grouting sealing device;

[0028] Figure 4 yes Figure 3 Enlarged schematic diagram of the structure at point B;

[0029] Figure 5 This is a longitudinal section diagram of the roadway construction in the method for preventing and controlling rockburst in roadways provided by the present invention.

[0030] Figure label:

[0031] 10. Tunnel; 11. Left side; 12. Right side; 20. Advance drilling; 30. Jet hole; 40. High-pressure pipe; 50. Grouting sealing device. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] The following is combined with Figures 1-5 The present invention describes a method for preventing coal face blasting in roadways prone to rock bursts, comprising the following steps:

[0034] Step 1: Conduct ground stress testing on the face of roadway 10 at the site;

[0035] Step 2: Collect coal samples from the coal seam at the face of roadway 10 and prepare them into specimens. Apply stress to the specimens and analyze the impact failure law of the specimens under stress loading.

[0036] Step 3: Take multiple specimens prepared in Step 2 and conduct drilling tests on them. Arrange a predetermined number of holes in each specimen. The diameter of the holes between specimens is different. After drilling, stress is applied to the specimens. Analyze the effect of different hole diameters on the impact failure of the specimens under stress loading and determine a reasonable hole diameter.

[0037] Step 4: Based on the borehole diameter determined in Step 3, take multiple samples obtained in Step 2 and conduct borehole grouting tests.

[0038] Step 5: Conduct advance drilling 20 at the face of roadway 10 to form advance drilling 20 on the coal seam of roadway sidewalls. Perform water jetting on advance drilling 20 to form jet holes 30 in the coal seam of roadway sidewalls.

[0039] Step 6: Based on the test results in Step 4, the jet hole 30 formed in Step 5 is modified by grouting.

[0040] The present invention provides a method for preventing and controlling coal face blasting in roadways prone to rock bursts. Step one optimizes the excavation direction of roadway 10 to reduce the intensity of blasting during excavation. Then, based on the experimental results from steps two to four, a reasonable borehole diameter is preliminarily determined, and grouting tests are conducted. In step five, jet holes 30 are created in the coal face to reduce the stress concentration level and elastic energy within the coal face, thereby reducing the impact tendency and intensity of the coal face during roadway 10 excavation. After completing step five, the jet holes 30 are modified by grouting, utilizing the bonding properties of the grouting material to help prevent coal face spalling and collapse during roadway 10 excavation. Through this method, problems such as coal face blasting, spalling, and deformation during roadway 10 excavation are effectively controlled, improving the problem of poor coal face formation, reducing the impact tendency of the coal body, and improving the integrity and strength of the coal face.

[0041] It is understood that, in some embodiments of the present invention, in step one, the hydraulic fracturing method is used to conduct in-situ stress testing on the coal seam of roadway 10 to investigate the stress state at the face of roadway 10 under impact, so as to obtain the magnitude and direction of the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress of the coal seam in the roadway sidewall. This can optimize the excavation direction of roadway 10 and reduce the intensity of blasting during the excavation of roadway 10. Of course, in some embodiments, the in-situ stress testing method can also be selected from stress relief methods, etc., and is not limited here.

[0042] In some embodiments of the present invention, in step two, the length of the sample is 'a', where 'a' is 30mm to 70mm, the width of the sample is 'b', where 'b' is 30mm to 70mm, and the height of the sample is 'c', where 'c' is 80mm to 120mm; in step three, a hole is drilled along the middle of the side of the sample, with one hole per sample, and the diameter of the hole ranges from 4mm to 10mm. Specifically, in this embodiment, the length of the sample (a) is chosen to be 50mm, the width (b) is chosen to be 50mm, and the height (c) is chosen to be 100mm, and four samples can be set, with the hole diameters of the four samples being 4mm, 6mm, 8mm, and 10mm respectively. The number of samples is not limited here.

[0043] It is understood that in some embodiments of the present invention, in step four above, different types of grout are injected into the boreholes of different samples during the grouting test, and stress loading is applied to the grouted samples to analyze the influence of different grouts on the strength and impact tendency of the samples under stress loading, thereby determining reasonable grouting materials and grouting process parameters.

[0044] It should be noted that, in some embodiments of the present invention, during the test of steps two to four above, the direction of the joints and fractures of the specimen is consistent with the loading direction, and the stress loading path is based on the ground stress level of the roadway 10 face measured on site. Using a universal servo testing machine, a three-dimensional full-field strain measurement system, a high-speed camera and an acoustic emission testing system, data such as the stress-strain curve, strain field, fracture field and acoustic emission of the specimen under uniaxial compression are obtained, thereby analyzing and determining reasonable borehole diameter, grouting material and grouting process parameters.

[0045] like Figure 1 and Figure 3 As shown, according to some embodiments of the present invention, based on the borehole diameter obtained in step three and the analysis of the field inspection results in step five, reasonable water jet process parameters are determined. These parameters include the jet pressure and the diameter of the jet orifice 30. Specifically, the jet pressure is determined based on the strength of the coal seam in the roadway side, and the diameter of the jet orifice 30 is determined based on the borehole diameter determined in step three. For example, if the borehole diameter of the above sample is 4 mm, then the diameter of the jet orifice 30 is 4 mm; if the borehole diameter is 6 mm, then the diameter of the jet orifice 30 is 6 mm, and so on. This allows for the control of the jet pressure, effectively and stably reducing the stress concentration level and elastic energy within the coal seam in the roadway side, thereby reducing the impact tendency and impact intensity of the coal seam in the roadway side during the excavation of roadway 10.

[0046] Furthermore, such as Figure 1 and Figure 3 As shown, according to some embodiments of the present invention, in step five, water jets are performed at intervals from the inside to the outside along the length direction of the advance borehole 20, i.e., in the direction of tunneling (e.g., ...). Figure 1 and Figure 3 Water jets are applied sequentially in the opposite direction to that indicated by arrow C. This segmented water jetting method facilitates the release of elastic energy within the coal seam of the roadway sidewalls, reduces stress concentration, and consequently lowers the impact tendency and intensity of the coal seam sidewalls during the excavation of roadway 10.

[0047] In some embodiments of the present invention, the length of the advance borehole 20 is 20m to 30m, and the jet pressure is 20MPa to 50MPa; wherein the interval between the centers of two adjacent jet holes 30 is 1.5m to 2.5m. Specifically, in this embodiment, the interval between the centers of two adjacent jet holes 30 is 2m, that is, water jetting is performed on the coal seam of the roadway every 2m.

[0048] Of course, in some embodiments, the interval between the centers of the two adjacent jet holes 30 is 1.5m or 2.5m, which is not limited here.

[0049] Reference Figure 2 and Figure 4 As shown, in some embodiments of the present invention, the water jet is selected as high-pressure water jet technology. Specifically, abrasive water jetting is used to perform high-pressure water jetting on the coal seam of the roadway side. It should be noted that in this embodiment, a drilling site is set up in the coal seam side, and a pre-drilling hole 20 is drilled in the coal seam side using the pre-drilling hole 20 technology. After the drilling is completed, a high-pressure pipe 40 is inserted into the pre-drilling hole 20 to perform the water jetting step, thereby forming a jet hole 30.

[0050] See Figures 1 to 4 As shown, both sides of the advanced borehole 20 have jet holes 30 to further reduce the elastic energy of the coal seam in the roadway.

[0051] It is understandable that the excavation direction of tunnel 10 is as follows: Figures 1-5 As shown, the advanced borehole 20 is located on the left side 11 of the coal seam in the roadway. Of course, the advanced borehole 20 can also be located on the right side 12 of the coal seam in the roadway, or in other locations. No limitation is made here.

[0052] According to some embodiments of the present invention, in step six, the jet hole 30 is grouted and modified sequentially from the inside to the outside along the length direction of the advance borehole 20, i.e., in the direction of tunneling (e.g., ...). Figure 1 and Figure 3 Grouting is carried out sequentially in the opposite direction to that indicated by the middle arrow C, with grouting area intervals of 1.5m to 2.5m. Specifically, in some embodiments of the present invention, the grouting area interval is 2m, that is, the grouting area interval corresponds to the interval of the water jet.

[0053] Of course, in some embodiments, the above-mentioned grouting area interval is 1.5m or 2.5m, which is not limited here.

[0054] It is understandable that, such as Figure 2 and Figure 4 As shown, in some embodiments of the present invention, in step six, based on the test results in step four and the analysis of on-site inspection results, reasonable grouting materials and grouting process parameters are determined. The grouting process parameters include the grouting volume and grouting pressure. Combining the research results of the comprehensive tests, namely the test results in step four and the on-site application effects, the grouting materials, grouting volume, and grouting pressure are determined to effectively prevent the coal seam from fracturing and collapsing during the excavation of roadway 10. It should be noted that in this embodiment, the grouting material tested in step four can be selected from different grouts such as cement grout and chemical grout.

[0055] Specifically, in step six, during grouting, the grouting volume is no less than 2t, and the grouting pressure ranges from 5MPa to 20MPa. Using a grouting volume of no less than 2t is sufficient to fully modify the jet orifice 30, resulting in a good grouting modification effect.

[0056] See Figure 2 and Figure 4 As shown, in some embodiments of the present invention, the above-mentioned grouting modification technology is carried out using a two-plug-one-injection grouting sealing method, that is, grouting sealing modification is performed using a grouting sealing device. Specifically, the grouting sealing device can be selected as a bag-type grouting sealing device. During grouting, the grouting pipe is sent to the designated position of the water jet, and the bag of the bag-type grouting sealing device seals both sides of the jet hole 30 in the pre-drilled hole 20. Then, the determined grouting material is injected into the corresponding jet hole 30 through the grouting port, thereby completing the grouting sealing. In some embodiments, the grouting sealing device can also be a bag-type (pressurized) grouting sealing device for gas drainage.

[0057] It is understood that in some embodiments of the present invention, the method further includes: Step 7, deploying monitoring equipment to monitor impact events in the coal seam at the roadway face during the excavation of roadway 10 and acquiring monitoring data, analyzing the monitoring data, and selecting whether to adjust and optimize the water jet process parameters, grouting materials, and grouting process parameters. Through monitoring data analysis, when the effect is significant, there is no need to adjust the water jet process parameters, grouting materials, and grouting process parameters. When the effect is not significant, relevant parameters can be adjusted, such as the water jet process parameters, grouting materials, and grouting process parameters, i.e., optimizing the diameter of the jet orifice 30, the grouting material, and the grouting pressure. This can achieve good control of rockburst prevention and side blasting in the coal seam at the face of roadway 10, thereby avoiding problems such as coal seam cracking and side slab spalling during the excavation of roadway 10.

[0058] It should be noted that the aforementioned monitoring equipment includes microseismic probes, ground sound probes, laser displacement meters, etc. These monitoring devices are installed at the face of roadway 10 to monitor data such as the energy of impact events on the coal seam of the roadway sidewalls, the displacement of the roadway sidewalls, and the formation of the roadway sidewalls during the excavation of roadway 10.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing coal face blasting in roadways prone to rock bursts, characterized in that, Includes the following steps: Step 1: Conduct ground stress testing at the face of the roadway. Step 2: Collect coal samples from the coal seam at the face of the roadway and prepare them into test specimens. Apply stress to the test specimens and analyze the impact failure law of the test specimens under stress loading. Step 3: Take multiple specimens prepared in Step 2 and conduct drilling tests on them. Arrange a predetermined number of holes in each specimen. The diameters of the holes between the specimens are different. After drilling, stress is applied to the specimens. Analyze the effect of different hole diameters on the impact failure of the specimens under stress loading and determine a reasonable hole diameter. Step 4: Based on the borehole diameter determined in Step 3, take multiple samples obtained in Step 2 and conduct borehole grouting tests. Step 5: Conduct advanced drilling at the face of the roadway to form advanced boreholes in the coal seam of the roadway side, and perform water jetting on the advanced boreholes to form jet holes in the coal seam of the roadway side. Step 6: Based on the test results in Step 4, perform grouting modification on the jet holes formed in Step 5; In step one, the hydraulic fracturing method is used to test the in-situ stress of the coal body in the roadway sidewalls to explore the stress state of the roadway face under rockburst, so as to obtain the magnitude and direction of the maximum horizontal principal stress, minimum horizontal principal stress and vertical stress of the coal body in the roadway sidewalls. In step two, the length of the sample is a, where a is 30mm to 70mm; the width of the sample is b, where b is 30mm to 70mm; and the height of the sample is c, where c is 80mm to 120mm. In step three, a hole is drilled along the middle of the side of the sample, with one hole for each sample, and the diameter of the hole for the sample ranges from 4 mm to 10 mm.

2. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 1, characterized in that, Based on the borehole diameter obtained from the test in step three and the analysis of the field inspection results in step five, reasonable water jet process parameters are determined, including the jet pressure and the diameter of the jet orifice. Specifically, the specific value of the jet pressure is determined based on the strength of the coal seam in the roadway, and the diameter of the jet hole is determined based on the borehole diameter determined in step three.

3. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 2, characterized in that, In step five, water jets are applied at intervals from the inside out along the length of the advanced borehole.

4. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 3, characterized in that, The length of the pre-drilled hole is 20m to 30m, and the jet pressure is 20MPa to 50MPa. The interval between the centers of two adjacent jet holes is 1.5m to 2.5m.

5. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 4, characterized in that, In step six, the jet holes are modified by grouting from the inside out along the length of the advanced borehole, with the grouting areas spaced 1.5m to 2.5m apart.

6. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rock bursts according to claim 5, characterized in that, In step six, based on the test results in step four and the analysis of the on-site inspection results, reasonable grouting materials and grouting process parameters are determined, including grouting volume and grouting pressure.

7. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 6, characterized in that, In step six, the grouting volume shall not be less than 2t, and the grouting pressure shall be in the range of 5MPa to 20MPa.

8. The method for preventing and controlling coal seam blasting at the face of a roadway prone to rockburst according to claim 6, characterized in that, Also includes: Step 7: Deploy monitoring equipment to monitor impact events in the coal seam along the roadway during tunnel excavation and acquire monitoring data. Analyze the monitoring data and determine whether to adjust and optimize the water jet process parameters, grouting materials, and grouting process parameters.

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