A method for evaluating the impact resistance of a roadway support

Abstract

An evaluation method for the impact resistance of roadway support, which utilizes a microseismic monitoring system to collect and record waveform signals of induced mine earthquakes in mining production, selects reliable channels with clear waveforms and easy to mark from the recorded signals, determines the source location and its spatial position relationship with the roadway by using P-wave arrival time analysis method, calculates the mine earthquake energy, selects waveform signals with larger energy near the roadway, establishes a roadway disaster model; a numerical simulation method is used to establish a numerical model that conforms to the actual situation; by applying different dynamic load amplitudes, the maximum PPV value that the roadway can resist is determined; according to the established roadway disaster model and the critical PPV value determined by numerical simulation, the PPV distribution contour map is drawn to evaluate the impact resistance of the roadway support system. The method can accurately evaluate the impact resistance of the roadway support system to determine the maximum energy that the roadway can resist at different distances from the source to the roadway.

Description

Technical Field

[0001] This invention relates to a method for assessing the impact resistance of roadway support, belonging to the field of coal mine safety mining technology. Background Technology

[0002] Rockbursts are a mining dynamic phenomenon caused by the sudden release of elastic energy accumulated in coal and rock masses, resulting in massive destruction. Their instantaneous explosiveness poses a serious threat to mine safety. Therefore, from both a safety and economic perspective, it is necessary to strengthen monitoring and take measures to mitigate or suppress rockbursts.

[0003] As roadways are directly affected by rockbursts, strengthening their own protection is of great significance in mitigating rockburst disasters. However, not all types of roadways require high-strength support components. For roadways with shallow burial or low rockburst potential, incurring huge costs to strengthen the support is clearly unnecessary. Therefore, it is necessary to evaluate the rockburst resistance of existing roadway support systems and strengthen the support of roadways that do not meet the rockburst prevention standards to achieve the required level.

[0004] Currently, there are few theoretical studies and evaluation methods for the impact resistance of roadway support systems for rockburst, and traditional methods for verifying the strength and deformation resistance of roadway support systems are not entirely applicable to the verification of roadway support systems for rockburst characterized by dynamic impact loads. Therefore, it is still impossible to accurately evaluate the ability of roadway support systems to resist rockburst. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for evaluating the impact resistance of roadway support. This method can accurately assess the ability of existing roadway support systems to resist rockbursts and determine the maximum energy that the roadway can resist at different distances from the earthquake source, thus providing a basis for roadway support.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for evaluating the erosion resistance of roadway support, comprising the following steps:

[0007] (1) Install a microseismic monitoring system in the coal mine, including ground acquisition and recording equipment and probes installed underground, and use the microseismic monitoring system to collect and record the seismic waveform signals induced during mining and production;

[0008] (2) For the mine seismic waveform signals recorded and stored in step (1), select reliable channels with clear waveforms and easy marking, use the P-wave arrival time analysis method, manually pick up the first arrival time of the P-wave, determine the location of the seismic source and its spatial relationship with the roadway under study, and calculate the mine seismic energy E.

[0009] (3) Select waveform signals with higher energy near the roadway under study, and extract the waveform signals from the first arrival to the end of the P wave on each reliable channel marked in step (2), and analyze the peak velocity of particle vibration recorded by each probe. Based on the probe's location and the vibration wave propagation law, the vibration amplitude of the vibration wave was calculated using the least squares method. and its propagation absorption coefficient in the rock mass A mine seismic attenuation model was established; through linear regression analysis, the mine seismic energy E and the vibration amplitude of the seismic wave were extracted. Based on the fitting coefficients, a disaster-causing model for roadways is established.

[0010] (4) Using numerical simulation, determine the size and material parameters of the model based on the geological environment near the roadway under study, and determine the strength, structural and anchoring parameters of the support components based on the existing support conditions, and establish a numerical model that conforms to the actual situation.

[0011] (5) After the simulated roadway excavation and support stabilization, the orientation of the dynamic load application is determined according to the spatial relationship between the earthquake source location and the roadway. By applying dynamic loads of different amplitudes, the damage to the roadway when the mine earthquake propagates to the roadway surface is studied to comprehensively determine the maximum PPV value that the roadway can resist.

[0012] (6) Based on the established roadway disaster model and the critical PPV value determined by numerical simulation, draw a contour map of PPV distribution, and then determine the maximum energy that the roadway can resist at different distances from the earthquake source, and finally evaluate the impact resistance of the roadway under the existing support system.

[0013] Furthermore, in step (1), the number of reliable channels with clear waveforms and easy marking is at least 4.

[0014] Furthermore, in step (2), the location of the earthquake source is obtained by modifying the Powell algorithm and determined by the following formula:

[0015] ;

[0016] In the formula:

[0017] w i The weighting function for the observations of each station;

[0018] n is the number of stations marked with P-wave;

[0019] t0 is the moment of origin of the earthquake.

[0020] t i Let be the time when the P-wave arrives at the i-th station;

[0021] Indicates the coordinates of the earthquake source;

[0022] Indicates the coordinates of the station;

[0023] P is a parameter, which can take the value of 1 or 2;

[0024] v ( ) represents the propagation speed of the P-wave in the medium.

[0025] Furthermore, in step (2), the method for calculating the seismic energy E is the energy density method, and the vibration velocity information is obtained by measuring the probe. and its energy density , The distance to the earthquake source; treating the seismic wave as a spherical wave, calculate the energy density. The value is based on a propagation radius of 500m, and energy attenuation is considered. Receive vibrational energy The calculation formula is:

[0026] .

[0027] Furthermore, in step (3), the established mine seismic attenuation model is as follows: , where r i The distance from the seismic source to the probe; the established roadway disaster model is... Where C is the fitting coefficient and r is the distance from the seismic source to the tunnel. This represents the critical PPV value at which the roadway fails.

[0028] Furthermore, in step (4), the numerical simulation method is FLAC. 3D FLAC 2D One of the following finite element or discrete element analysis methods: UDEC, 3DEC, PFC;

[0029] The material parameters of the model include density, shear modulus, bulk modulus, cohesion, internal friction angle, and tensile strength; the strength parameters of the support components include Young's modulus, tensile yield strength, and density of the support unit; the structural parameters of the support components include the length, row spacing, row spacing, and cross-sectional area of ​​the support unit; the anchoring parameters of the support components include the bonding force of cement grout per unit length, the friction angle of cement grout, the shear stiffness of cement grout per unit length, and the perimeter of the cement grout.

[0030] Furthermore, in step (5), the method of applying the dynamic load is one of acceleration time history, velocity time history, or stress time history loading; the velocity time history is expressed by the formula: and Converted to stress time history, where , ;

[0031] The characterization methods for roadway damage are as follows: for discrete element simulation, the damage condition of the roadway is directly observed; for finite element simulation, the relative displacement of the roadway surface is monitored, and when it is greater than 3%, the roadway is considered to have been damaged.

[0032] This invention utilizes a microseismic monitoring system installed in coal mines to collect and record seismic waveforms induced during mining operations. From these recorded signals, reliable channels with clear and easily labeled waveforms are selected. P-wave arrival time analysis is employed to determine the location of the seismic source and its spatial relationship with the studied roadway, and the seismic energy is calculated. Waveforms with higher energy near the studied roadway are selected, and linear regression analysis is used to extract the fitting coefficients between the seismic energy and the vibration amplitude of the seismic wave, establishing a roadway disaster model. Numerical simulation is then used to establish a numerical model that conforms to actual conditions. By applying different dynamic load amplitudes, the damage to the roadway when the seismic propagation reaches the roadway surface is studied to comprehensively determine the maximum PPV (Power, Partial Vibration Value) that the roadway can withstand. Based on the established roadway disaster model and the critical PPV value determined through numerical simulation, a PPV distribution contour map is drawn to determine the maximum energy that the roadway can withstand at different distances from the seismic source. Finally, the impact resistance of the roadway under the existing support system is evaluated. This invention enables a reasonable classification and evaluation of the impact resistance of different types of roadway support systems, and determines the maximum seismic energy that the support system can resist when different seismic sources propagate to different distances in the roadway. This greatly improves the accuracy of the evaluation of the ability of existing roadway support systems to resist rockbursts. It is applicable to the verification of roadway support for rockbursts characterized by dynamic impact loads, and provides a theoretical basis for roadway support. Attached Figure Description

[0033] Figure 1 This is the first mine seismic attenuation model established in this invention;

[0034] Figure 2 This is the second mine seismic attenuation model established in this invention;

[0035] Figure 3 This is the third mine seismic attenuation model established in this invention;

[0036] Figure 4 This is the fourth mine seismic attenuation model established in this invention;

[0037] Figure 5 This is the fifth mine seismic attenuation model established by this invention;

[0038] Figure 6 This is the sixth mine seismic attenuation model established in this invention;

[0039] Figure 7 This is a schematic diagram of the deformation of the left side of the roadway after dynamic load is applied in an embodiment of the present invention;

[0040] Figure 8 This is a schematic diagram of the deformation of the right side of the roadway after dynamic load is applied in an embodiment of the present invention;

[0041] Figure 9 This is a schematic diagram of the deformation of the roadway roof after dynamic load is applied in an embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram of the deformation of the roadway floor after dynamic load is applied in an embodiment of the present invention;

[0043] Figure 11 This is a contour map of PPV distribution according to an embodiment of the present invention. Detailed Implementation

[0044] The invention will now be further described with reference to the accompanying drawings.

[0045] A method for assessing the scour resistance of roadway support includes the following steps:

[0046] (1) Install a microseismic monitoring system in the coal mine, including ground acquisition and recording equipment and probes installed underground, and use the microseismic monitoring system to collect and record the seismic waveform signals induced during mining and production;

[0047] (2) For the mine seismic waveform signals recorded and stored in step (1), select reliable channels with clear waveforms and easy marking, use the P-wave arrival time analysis method, manually pick up the first arrival time of the P-wave, determine the location of the seismic source and its spatial relationship with the roadway under study, and calculate the mine seismic energy E.

[0048] (3) Select waveform signals with higher energy near the roadway under study, and extract the waveform signals from the first arrival to the end of the P wave on each reliable channel marked in step (2), and analyze the peak velocity of particle vibration recorded by each probe. Based on the probe's location and the vibration wave propagation law, the vibration amplitude of the vibration wave was calculated using the least squares method. and its propagation absorption coefficient in the rock mass A mine seismic attenuation model was established; through linear regression analysis, the mine seismic energy E and the vibration amplitude of the seismic wave were extracted. Based on the fitting coefficients, a disaster-causing model for roadways is established.

[0049] (4) Using numerical simulation, determine the size and material parameters of the model based on the geological environment near the roadway under study, and determine the strength, structural and anchoring parameters of the support components based on the existing support conditions, and establish a numerical model that conforms to the actual situation.

[0050] (5) After the simulated roadway excavation and support stabilization, the orientation of the dynamic load application is determined according to the spatial relationship between the earthquake source location and the roadway. By applying dynamic loads of different amplitudes, the damage to the roadway when the mine earthquake propagates to the roadway surface is studied to comprehensively determine the maximum PPV value that the roadway can resist.

[0051] (6) Based on the established roadway disaster model and the critical PPV value determined by numerical simulation, draw a contour map of PPV distribution, and then determine the maximum energy that the roadway can resist at different distances from the earthquake source, and finally evaluate the impact resistance of the roadway under the existing support system.

[0052] To improve the accuracy of the evaluation, in step (1), at least four reliable channels with clear waveforms and easy marking are selected.

[0053] In a preferred embodiment, in step (2), the location of the earthquake source is obtained by a modified Powell algorithm and determined by the following formula:

[0054] ;

[0055] In the formula:

[0056] w i The weighting function for the observations of each station;

[0057] n is the number of stations marked with P-wave;

[0058] t0 is the moment of origin of the earthquake.

[0059] t i Let be the time when the P-wave arrives at the i-th station;

[0060] Indicates the coordinates of the earthquake source;

[0061] Indicates the coordinates of the station;

[0062] P is a parameter, which can take the value of 1 or 2;

[0063] v ( ) represents the propagation speed of the P-wave in the medium.

[0064] Furthermore, in step (2), the method for calculating the seismic energy E is the energy density method, and the vibration velocity information is obtained by measuring the probe. and its energy density , The distance to the earthquake source; treating the seismic wave as a spherical wave, calculate the energy density. The value is based on a propagation radius of 500m, and energy attenuation is considered. Receive vibrational energy The calculation formula is:

[0065] .

[0066] In a preferred embodiment, the established mine seismic attenuation model in step (3) is as follows: , where r i The distance from the seismic source to the probe; the established roadway disaster model is... Where C is the fitting coefficient and r is the distance from the seismic source to the tunnel. This represents the critical PPV value at which the roadway fails.

[0067] In a preferred embodiment, the numerical simulation method in step (4) is FLAC. 3D FLAC 2D One of the following finite element or discrete element analysis methods: UDEC, 3DEC, PFC;

[0068] The material parameters of the model include density, shear modulus, bulk modulus, cohesion, internal friction angle, and tensile strength; the strength parameters of the support components include Young's modulus, tensile yield strength, and density of the support unit; the structural parameters of the support components include the length, row spacing, row spacing, and cross-sectional area of ​​the support unit; the anchoring parameters of the support components include the bonding force of cement grout per unit length, the friction angle of cement grout, the shear stiffness of cement grout per unit length, and the perimeter of the cement grout.

[0069] In a preferred embodiment, in step (5), the method of applying the dynamic load is one of acceleration time history, velocity time history, or stress time history loading; the velocity time history is expressed by the formula: and Converted to stress time history, where , ;

[0070] The characterization methods for roadway damage are as follows: for discrete element simulation, the damage condition of the roadway is directly observed; for finite element simulation, the relative displacement of the roadway surface is monitored, and when it is greater than 3%, the roadway is considered to have been damaged.

[0071] Example:

[0072] This method was used to demonstrate the support capabilities for mine roadways prone to rockbursts in the Dongxia Coal Mine. The specific steps are as follows:

[0073] (1) A microseismic monitoring network is formed by using the above-ground acquisition and recording equipment and the probe installed underground in the coal mine. The vibration waves released by the mine seismic activity in the coal and rock mass during the working face production and roadway excavation process are collected in real time at a sampling frequency of 500Hz. The mine seismic signals fed back by each receiving channel are recorded in real time through the ground receiving unit.

[0074] (2) Select microseismic signals within a certain time period, select the waveform channel with relatively clear signals, and manually pick up the arrival time of the P wave. Analyze the seismic energy and the spatial relationship between the source location and the roadway location, and calculate the seismic energy E.

[0075] (3) Select six high-energy waveform signals near the roadway, extract the waveform from the first arrival to the end of the P wave on each signal channel, and analyze the peak velocity of particle vibration recorded by each probe. Based on the probe's location and the vibration wave propagation law, the vibration amplitude of the vibration wave was calculated using the least squares method. and its propagation absorption coefficient in the rock mass ;like Figures 1 to 6 As shown in the figure, the correlation coefficient R is displayed. 2 All values ​​are greater than 0.8, indicating a good fit. Linear regression analysis was used to extract the seismic energy E and the vibration amplitude of the seismic wave. The fitting coefficient C is 7.01 × 10⁻⁶. -5 The disaster-causing model for the alleyway is as follows: r represents the distance from the earthquake source to the tunnel;

[0076] (4) Based on the geological environment around the roadway and the borehole columnar section, the model size was determined to be 40m×40m×40m, the coal seam dip angle was 25°, and the lithology and parameters of the coal seam and its roof and floor are shown in Table 1:

[0077] Table 1 Mechanical parameters of coal and rock strata

[0078]

[0079] Eight sets of anchor bolts are installed on the top of the roadway, with a spacing of 700 mm; the reinforcement anchor cables are arranged in a "five-four-five" pattern, with a spacing of 1000 mm; other material parameters of the support components are shown in Table 2.

[0080] Table 2 Other Material Parameters for Support Components

[0081]

[0082] Anchoring parameters are shown in Table 3:

[0083] Table 3 Anchorage Parameters of Support Components

[0084]

[0085] As can be seen from the above analysis, the selected mine tremors are mostly located below the roadway. Therefore, after simulating the excavation and stabilization of the roadway, dynamic loads of different amplitudes were applied to the bottom of the model: 0.1 m / s, 0.2 m / s, 0.3 m / s, 0.4 m / s, 0.5 m / s, and 0.6 m / s. When the mine tremors propagate to the roadway, the damage to the roadway is analyzed by studying the displacement of the roadway surface. The design scheme, monitoring results, roadway dimensions, and relative deformation at the point of failure are shown in Tables 4 and 5, respectively.

[0086] Table 4. Dynamic load application speed and monitoring results

[0087]

[0088] In Table 4, PPV0 is the peak particle velocity of the applied dynamic load; PPV1 is the peak particle velocity of the dynamic load transmitted to the left side of the roadway; PPV2 is the peak particle velocity of the dynamic load transmitted to the right side of the roadway; PPV3 is the peak particle velocity of the dynamic load transmitted to the roof; and PPV4 is the peak particle velocity of the dynamic load transmitted to the bottom.

[0089] Table 5. Deformation of the tunnel

[0090]

[0091] like Figures 7 to 10 It can be seen that when the velocity of the dynamic load propagating to the surface of the roadway is 0.52 m / s, the relative deformation of the roadway floor reaches the level that characterizes the roadway damage. Therefore, it can be confirmed that the velocity at this time is the PPV critical value for the roadway to reach the damage, that is, the maximum PPV value that the roadway can resist is about 0.5 m / s.

[0092] (5) Using the obtained tunnel disaster model And the maximum PPV value that the tunnel can withstand, determined through simulation. =0.5m / s, thus obtaining the final disaster-causing model expression for the roadway. and draw as follows Figure 11 The PPV distribution contour map shown is shown.

[0093] From the PPV distribution contour map, it can be concluded that regardless of the type of mine seismic propagation model, when the earthquake energy magnitude is less than 3.85, the PPV value will not exceed the critical impact velocity of 0.5 m / s determined through simulation. Therefore, regardless of the distance between the seismic source and the roadway, the existing roadway support system on the 37221-1 working face of Dongxia Coal Mine can withstand energy less than 10... 3.85 J, i.e., 7.08e 3For mine earthquakes below J, the larger the energy of the earthquake, the larger the volume of surrounding rock required to accumulate energy. Typically, the rupture radius of high-energy mine earthquakes is over 50 meters. Considering the impact of low-lying rock strata decompression and prevention projects, after taking into account the volume of energy accumulated in the surrounding rock and the rupture range of the earthquake source, when the roadway is 50 meters from the earthquake source, the maximum mine earthquake energy that can be resisted is 10. 5.62 J, i.e., 4.17e 5 J.

Claims

1. A method for evaluating the erosion resistance of roadway support, characterized in that, Includes the following steps: (1) Install a microseismic monitoring system in the coal mine, including ground acquisition and recording equipment and probes installed underground, and use the microseismic monitoring system to collect and record the seismic waveform signals induced during mining and production; (2) For the mine seismic waveform signals recorded and stored in step (1), select reliable channels with clear waveforms and easy marking, use the P-wave arrival time analysis method, manually pick up the first arrival time of the P-wave, determine the location of the seismic source and its spatial relationship with the roadway under study, and calculate the mine seismic energy E. (3) Select waveform signals with higher energy near the roadway under study, and extract the waveform signals from the first arrival to the end of the P wave on each reliable channel marked in step (2), and analyze the peak velocity of particle vibration recorded by each probe. Based on the probe's location and the vibration wave propagation law, the vibration amplitude of the vibration wave was calculated using the least squares method. and its propagation absorption coefficient in the rock mass A mine seismic attenuation model was established; through linear regression analysis, the mine seismic energy E and the vibration amplitude of the seismic wave were extracted. Based on the fitting coefficients, a disaster-causing model for roadways is established. (4) Using numerical simulation, determine the size and material parameters of the model based on the geological environment near the roadway under study, and determine the strength, structural and anchoring parameters of the support components based on the existing support conditions, and establish a numerical model that conforms to the actual situation. (5) After the simulated tunnel excavation and support are stabilized, the orientation of the dynamic load is determined according to the spatial relationship between the earthquake source location and the tunnel. By applying dynamic loads of different amplitudes, the damage to the roadway when the mine earthquake propagates to the roadway surface is studied to comprehensively determine the maximum PPV value that the roadway can resist. (6) Based on the established roadway disaster model and the critical PPV value determined by numerical simulation, draw a contour map of PPV distribution, and then determine the maximum energy that the roadway can resist at different distances from the earthquake source, and finally evaluate the impact resistance of the roadway under the existing support system.

2. The method for evaluating the erosion resistance of roadway support according to claim 1, characterized in that, In step (1), at least four reliable channels with clear waveforms and easy marking are selected.

3. A method for evaluating the erosion resistance of roadway support according to claim 1 or 2, characterized in that, In step (2), the location of the earthquake source is obtained by modifying the Powell algorithm and determined by the following formula: ； In the formula: w i The weighting function for the observations of each station; n is the number of stations marked with P-wave; t0 is the time of origin of the earthquake. t i Let be the time when the P-wave arrives at the i-th station; Indicates the coordinates of the earthquake source; Indicates the coordinates of the station; P is a parameter, which can take the value of 1 or 2; v ( ) represents the propagation speed of the P-wave in the medium.

4. The method for evaluating the erosion resistance of roadway support according to claim 3, characterized in that, In step (2), the seismic energy E is calculated using the energy density method, and the vibration velocity information is obtained by measuring the vibration velocity information through a probe. and its energy density , The distance to the epicenter; Treating the vibration wave as a spherical wave, the energy density is calculated. The value is based on a propagation radius of 500m, and energy attenuation is considered. Receive vibrational energy The calculation formula is: 。 5. A method for evaluating the erosion resistance of roadway support according to claim 1 or 2, characterized in that, In step (3), the established mine seismic attenuation model is as follows: , where r i The distance from the seismic source to the probe; the established roadway disaster model is... Where C is the fitting coefficient and r is the distance from the seismic source to the tunnel. This represents the critical PPV value at which the roadway fails.

6. The method for evaluating the erosion resistance of roadway support according to claim 3, characterized in that, In step (4), the numerical simulation method is FLAC. 3D FLAC 2D One of the following finite element or discrete element analysis methods: UDEC, 3DEC, PFC; The material parameters of the model include density, shear modulus, bulk modulus, cohesion, internal friction angle, and tensile strength; the strength parameters of the support components include Young's modulus, tensile yield strength, and density of the support unit; the structural parameters of the support components include the length, row spacing, row spacing, and cross-sectional area of ​​the support unit; the anchoring parameters of the support components include the bonding force of cement grout per unit length, the friction angle of cement grout, the shear stiffness of cement grout per unit length, and the perimeter of the cement grout.

7. The method for evaluating the erosion resistance of roadway support according to claim 3, characterized in that, In step (5), the method of applying the dynamic load is one of acceleration time history, velocity time history, or stress time history loading; the velocity time history is expressed by the formula: and Converted to stress time history, where , ; The characterization methods for roadway damage are as follows: for discrete element simulation, the damage condition of the roadway is directly observed; for finite element simulation, the relative displacement of the roadway surface is monitored, and when it is greater than 3%, the roadway is considered to have been damaged.

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