An infrared monitoring method and device for roadway stress to solve the influence of air flow

Abstract

The present invention is applicable to the fields of mine safety and rock mechanics, and provides a method and device for infrared monitoring of roadway stress to solve the influence of air flow. The method includes: calculating the heat exchange amount between the surrounding rock of the roadway in the mine and the air flow, and calculating the magnitude of the temperature influence of the air flow on the surrounding rock of the roadway through the relationship between the heat exchange amount and the temperature, and removing it, leaving only the temperature difference caused by different stress distributions of the surrounding rock of the roadway. Then, the temperature field of the surrounding rock of the roadway affected by the air flow is removed, and combined with the coupled thermodynamics of the temperature field change caused by rock deformation, the relationship between the temperature field change obtained by the elastic thermal effect during the deformation process of the surrounding rock of the roadway and the stress field is utilized. Based on the infrared thermal imaging technology, the present invention measures the stress of the surrounding rock of the roadway by removing the influence of the air flow, and judges the possible occurrence position of rock burst according to the displayed stress magnitude, and can predict the occurrence of disasters.

Description

Technical Field

[0001] The present invention belongs to the technical fields of mine safety and rock mechanics, and particularly relates to a roadway stress infrared monitoring method and device for solving the influence of air flow. Background Art

[0002] China is a major mining country with many major mining projects. With the development of China's mining industry, more and more mine rock burst disasters have occurred frequently. The main reason for these problems is that during the mining process, the hard and brittle rock mass changes its original stress structure due to excavation unloading, so that the original stable and safe stress structure changes, resulting in dynamic instability geological disasters such as bursting, loosening, spalling, ejection, and even throwing, endangering the interests and safety of the working people. Therefore, effective prediction and identification of the process of mine disasters have become the main direction of mine disaster early warning and disaster prevention and mitigation. Therefore, it is very meaningful to develop a stress detection system.

[0003] At present, the research on the prevention technology of rock burst risk mainly lies in the acoustic field. Specifically, in the acoustic field, it is divided into three directions: microseismic technology, acoustic emission technology, and audio frequency detection technology. These three methods can predict rock burst risk to a certain extent. However, under the influence of environmental factors in actual roadways, false alarms often occur. The current system has not reached the level of intelligent judgment, and the results presented by these three technologies are very unintuitive. Professional personnel are required to analyze to determine the possible location of rock burst, which is affected by certain subjective factors.

[0004] Since the gestation of rock burst is a process in which the rock mass absorbs energy under the action of excavation disturbance, the rock mass will release corresponding infrared spectra due to the absorbed energy at different stages. Existing research has found that the infrared radiation temperature of rocks changes with rock stress. This is mainly because the strain energy of rock deformation at the position of the surrounding rock of the roadway with large stress is converted into radiant energy, directly resulting in infrared temperature increase. Therefore, more stable and intuitive infrared thermal imaging technology is introduced to detect the temperature field of the roadway surrounding rock to prevent rock burst. There are also infrared detection systems on the market that detect the possible location of rock burst according to the magnitude of the infrared radiation temperature. However, the current infrared detection systems still have deficiencies. First, the infrared radiation temperature of the roadway surrounding rock is easily affected by the air flow in the roadway, and there is no method to remove the influence of the air flow on the infrared radiation temperature of the roadway surrounding rock. Second, there is currently no device that can directly observe the magnitude of the stress of the roadway surrounding rock. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a roadway stress infrared monitoring method and device for solving the influence of air flow, aiming to solve the above technical problems.

[0006] The present invention adopts the following technical solutions:

[0007] On the one hand, the infrared monitoring method for roadway stress to solve the influence of air flow includes the following steps:

[0008] Step S1: Obtain the thermophysical coefficients of the surrounding rock of the roadway and the size parameters of the roadway;

[0009] Step S2: Calculate the radius of the heat-adjusting circle, and combine the original rock temperature and the temperature measurement value of a temperature measurement point in the surrounding rock of the roadway to calculate the heat flux density of the final roadway surrounding rock wall surface, and then obtain the heat of heat exchange between the air flow and the roadway surrounding rock;

[0010] Step S3: Calculate the temperature change value of the air flow on the temperature field of the roadway surrounding rock according to the corresponding relationship between heat and temperature;

[0011] Step S4: By measuring the temperature values of each pixel of the infrared temperature field of the roadway surrounding rock wall surface affected by the air flow and stress, and combining the temperature change value, finally obtain the infrared temperature field image of the roadway surrounding rock wall surface affected only by stress without air flow;

[0012] Step S5: Obtain the average temperature value of the test block without air flow and not affected by stress, calculate the difference between each pixel of the infrared temperature field image of the roadway surrounding rock wall surface and the average temperature value of the test block, then calculate the stress tensor change of each pixel point, and finally convert it into the stress value of each pixel point.

[0013] On the other hand, the infrared monitoring device for roadway stress to solve the influence of air flow includes an infrared thermal imager, a laser ranging device and an ultrasonic wind speed and temperature measuring instrument. The infrared monitoring device for roadway stress also has an industrial control board built in, and the industrial control board is used to execute the infrared monitoring method for roadway stress.

[0014] The beneficial effects of the present invention are as follows: The present invention uses an ultrasonic wind speed and temperature measuring instrument to measure the wind speed and temperature in the roadway, and then takes the wind speed as a variable, combines the temperature difference between the surrounding rock and the air flow temperature in the roadway, and fits the calculation formula of the convective heat transfer coefficient, which solves the problem that the measurement of the infrared temperature field of the roadway surrounding rock by the infrared thermal imaging method is affected by the air flow. The present invention uses thermal infrared radiation to study and explore the stress distribution and interaction of the roadway surrounding rock. Based on the thermodynamic theory, heat transfer theory, and comparison with the observation results in the laboratory, the evolution trend and amplitude of temperature and stress are in good agreement, and it has a good application prospect. Description of the Drawings

[0015] Figure 1 is the flow chart of the infrared monitoring method for roadway stress to solve the influence of air flow provided by the embodiment of the present invention;

[0016] Figure 2 is the schematic diagram of the radius of the heat-adjusting circle provided by the embodiment of the present invention;

[0017] Figure 3 is a perspective view of the roadway stress infrared monitoring device for solving the influence of air flow provided by the embodiment of the present invention;

[0018] Figure 4 is a rear view of the roadway stress infrared monitoring device for solving the influence of air flow provided by the embodiment of the present invention. Detailed implementation manners

[0019] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] In order to illustrate the technical solutions described in the present invention, the following will be described through specific embodiments.

[0021] Example 1:

[0022] As Figure 1 shown, the roadway stress infrared monitoring method for solving the influence of air flow provided in this embodiment includes the following steps:

[0023] Step S1: Obtain the thermophysical coefficients of the roadway surrounding rock and the roadway dimension parameters.

[0024] First, obtain the thermophysical coefficients of the roadway surrounding rock to be mined in the laboratory, including the thermal conductivity λ, specific heat C, density ρ, heat capacity Cρ, and thermal diffusivity α. These parameters are all constants and can be directly input after measurement.

[0025] Then, measure the roadway dimension parameters through a laser ranging device, including the hydraulic radius r0 of the roadway, the measured wall area S, etc. In addition, there are also the roadway perimeter, roadway cross-sectional area, etc., and output each dimension parameter.

[0026] Step S2: Calculate the radius of the heat-adjusting circle, and combine the original rock temperature and the temperature measurement value of a temperature measurement point in the roadway surrounding rock body to calculate the final heat flux density of the roadway surrounding rock wall surface, and then obtain the heat of the heat exchange between the air flow and the roadway surrounding rock.

[0027] In this step, calculate the radius of the heat-adjusting circle through the heat-adjusting circle radius calculation formula. Before calculating the radius of the heat-adjusting circle, it is necessary to use a borehole to measure the change in the original rock temperature ty and the temperature Y at a depth re in the roadway surrounding rock body. Specifically, after drilling, put the temperature measurement sensor in, and use the temperature measurement sensor to measure the original rock temperature ty at a distance of 1.5 m from the roadway surrounding rock wall surface. When measuring the temperature Y at the depth re inside the rock, the depth of the borehole should not exceed the radius rt of the heat-adjusting circle.

[0028] In this embodiment, a drilling method is adopted to measure the original rock temperature and the temperature change in the surrounding rock by a temperature measuring sensor, so as to calculate the heat flux density value of the roadway surrounding rock wall surface subsequently. The depth of the drill hole, that is, the temperature measuring point, should be able to fully reflect the change of the rock temperature. In this embodiment, a pneumatic drill is used for drilling. During the drilling process, the pneumatic drill uses circulating water as the drilling fluid, which can not only cool the heat generated by the friction of the drill tool, but also has a certain cooling effect on the rock temperature, and the original rock temperature is measured during drilling. The drill hole depth should not be too shallow. If it is too close to the wall surface, the change of the rock temperature is greatly affected by the air flow and the interference is too strong. However, it should not be too deep so as to exceed the outer radius of the heat regulation circle of the roadway. If the temperature measuring point exceeds the outer radius of the heat regulation circle of the roadway, the temperature change will not be measured. The selection of the temperature measuring instrument has a great influence on the accuracy of the measured temperature. The higher the accuracy, the closer the measured temperature is to the true value, the smaller the data error, and the smaller the error of the estimated heat flux density value. Measuring the temperature in the deep part of the rock with a temperature measuring sensor can avoid the influence of the change of the air flow state in the roadway on the temperature measuring accuracy.

[0029] The calculation formula for the radius of the heat regulation circle is rt = r0+(r0 2 +12αt) 1 / 2 , where the hydraulic radius of the roadway is r0, the thermal diffusivity is α, and the time required for borehole temperature measurement is t. At the outer boundary of the heat regulation circle, the initial temperature of the surrounding rock is maintained at t0, and t0 = ty. The schematic diagram of the radius of the heat regulation circle is as Figure 2 shown. After measurement, the original rock temperature ty and the temperature Y at a depth re inside the rock are used as parameters for input.

[0030] Since the surrounding rock of the roadway continuously exchanges heat with the air flow, the value of its heat flux density may be positive or negative. When the heat flux density is negative, the surrounding rock transfers heat to the air flow, and the temperature of the surrounding rock wall surface is higher than the temperature of the air flow; when it is positive, the surrounding rock absorbs the heat in the air flow, and at this time the air flow temperature is higher than the temperature of the surrounding rock wall surface. Through the measured temperature value Y at the depth re inside the surrounding rock, the heat flux density qe of the temperature measuring point in the surrounding rock body of the roadway can be obtained:

[0031]

[0032] After calculation by this formula, the heat flux density q of the final roadway surrounding rock wall surface is obtained:

[0033]

[0034] Multiply the calculated heat flux density q by the measured wall surface area S to obtain the heat Q1 of the heat exchange between the air flow and the roadway surrounding rock.

[0035] Step S3: Calculate the temperature change value of the air flow on the temperature field of the roadway surrounding rock according to the corresponding relationship between heat and temperature.

[0036] The corresponding relationship between heat and temperature is Q1 = a(t2 - t1)*S, where t1 is the temperature value affected only by stress under the condition of no wind, t2 is the temperature value affected by stress under the condition of wind, a is the convective heat transfer coefficient, which is related to wind speed and wind temperature, and S is the measured wall surface area, which has been measured by a laser ranging device. From the corresponding relationship between heat and temperature, the temperature influence of the air flow on the surrounding rock wall can be obtained, and (t2 - t1) is the temperature change value of the air flow on the temperature field of the roadway surrounding rock.

[0037] The calculation method of the convective heat transfer coefficient a here is as follows: Using the wind speed and wind temperature values measured by an ultrasonic wind speed and wind temperature measuring instrument, taking the roadway wind speed as a variable, and combining with the temperature difference between the surrounding rock and the air flow in the roadway, a calculation formula for the convective heat transfer coefficient is fitted, and finally the convective heat transfer coefficient a is calculated. Since Q1, a, and S have been calculated, according to the corresponding relationship between heat and temperature, the temperature change amount (t2 - t1) of the roadway surrounding rock wall under the influence of no wind can be calculated.

[0038] Step S4: By measuring the temperature values of each pixel of the infrared temperature field of the roadway surrounding rock wall affected by air flow and stress, and combining with the temperature change value, finally obtain the infrared temperature field image of the roadway surrounding rock wall affected only by stress without air flow.

[0039] Using an infrared thermal imager to measure the temperature values of each pixel of the infrared temperature field of the roadway surrounding rock wall affected by air flow and stress. Suppose there are n pixels, and the temperature values are [T1, T2, T3... Tn] respectively. Subtract the temperature change value (t2 - t1) from each pixel temperature value to obtain the infrared temperature field image of the roadway surrounding rock wall affected only by stress without air flow. The temperature of each pixel in the image is [T01, T02, T03... T0n] respectively, and finally display the infrared temperature field image affected only by stress without air flow.

[0040] Step S5: Obtain the average temperature value of the specimen without air flow and without stress influence, calculate the difference between each pixel of the infrared temperature field image of the roadway surrounding rock wall and the average temperature value of the specimen, then obtain the change of the stress tensor at each pixel point through calculation, and finally convert it into the stress value at each pixel point.

[0041] During the deformation process of the material, there is a change in the temperature field. The relationship between the elastic deformation of the material and the change in the temperature field is the elastic thermal effect. The elastic thermal effect can be used to explain the deformation of the roadway surrounding rock, which is also the change in the temperature field during the stress change process. Through the aforementioned algorithm for removing the influence of air flow on the temperature of the roadway surrounding rock, the temperature field of the roadway surrounding rock wall without the influence of wind is obtained, which indicates that the processed temperature field of the roadway surrounding rock is only affected by the stress field. In this step, the state of the stress field of the roadway surrounding rock at this time is deduced through this temperature field.

[0042] The relational expression between the rock temperature change and the change in the stress tensor it receives is:

[0043] T0i - T00 = -T00 × a / (ρ * Cρ) × Δδkk

[0044] Where T0i is the pixel temperature value of the infrared temperature field image of the surrounding rock wall of the roadway affected only by stress without air flow, that is, the temperature values [T01, T02, T03... T0n] of each pixel of the infrared temperature field image of the surrounding rock affected only by stress under the condition of no air flow as mentioned above. T00 is the average temperature value of the specimen without air flow and not affected by stress. a is the convective heat transfer coefficient, ρ is the density of the rock mass, Cρ is the heat capacity of the rock mass, and Δδkk is the change in the stress tensor.

[0045] Since T0i, a, ρ, and Cρ are known, therefore, only a small specimen needs to be placed in a windless place in the mine in advance. The stress of this specimen can be considered negligible compared with the stress of the surrounding rock of the roadway and is considered to be 0. Therefore, the average temperature value T00 of the specimen not affected by stress under the condition of no air flow can be measured by an infrared thermal imager. Finally, according to the formula, the change in the stress tensor Δδkk can be calculated, and the change in the measured stress tensor Δδkk is converted into a stress value and displayed on the screen, then the stress values of each part of the surrounding rock of the roadway can be intuitively seen.

[0046] In the experiment of uniaxial loading of rock specimens of various different forms using an infrared thermal imaging instrument, it was found that: (1) During the uniaxial loading process, the infrared radiation temperature of the ore changes with stress: it is calm or slightly decreases at the initial stage of loading, then slowly rises, and rises rapidly before fracture; (2) When the ore enters the failure process from the stress peak stage, the thermal image shows that the low-temperature area expands, and the low-temperature band is the position of the subsequent main fracture; (3) With the increase of stress, the infrared radiation spectrum of the rock significantly increases in radiation intensity while keeping its shape basically unchanged, and the infrared radiation intensity reaches the highest value before the rock fractures. Therefore, the stable and intuitive infrared thermal imaging technology can be used to detect the temperature field of the surrounding rock of the roadway to prevent rock bursts.

[0047] However, after excavating a roadway in the rock, when an air flow with a temperature lower than that of the surrounding rock passes through, due to the temperature difference, the roadway wall releases heat to the air flow in the form of convective heat transfer, and the surrounding rock mass generates heat flow to the cooled roadway wall in the form of heat conduction. At the same time, the surrounding rock mass in the deep part is also cooled accordingly to form a cooling zone. After the air flow in the roadway obtains heat, its temperature rises, and the temperature distribution of the surrounding rock mass and the air temperature in the roadway change with time, which is an unstable heat transfer process. This process includes the heat conduction inside the surrounding rock mass and the convective heat transfer between the surrounding rock and the air flow, and it is a combined unstable heat transfer process. Therefore, in order to better use the infrared thermal imaging technology to detect the temperature field of the surrounding rock of the roadway, it is necessary to eliminate the influence of the air flow on the temperature field of the surrounding rock of the roadway.

[0048] This embodiment provides a method to solve this problem. By calculating the heat exchange amount between the roadway surrounding rock and the air flow in the mine, and using the relational expression between the heat exchange amount and temperature to calculate the temperature influence of the air flow on the roadway surrounding rock and remove it, only leaving the temperature difference caused by different stress distributions in the roadway surrounding rock. Then, the temperature field of the roadway surrounding rock affected by the air flow is removed through the algorithm for removing the temperature of the roadway surrounding rock affected by the air flow, combined with the coupled thermodynamics of the temperature field change caused by rock deformation. Using the relational expression between the temperature field change and the stress field obtained from the elastic thermal effect during the deformation process of the roadway surrounding rock, an overall algorithm is formed to obtain the stress values at different positions of the roadway surrounding rock.

[0049] Example 2:

[0050] The stress value is the most intuitive way to observe whether rock burst occurs in the roadway surrounding rock. Based on the method described in Embodiment 1, this embodiment designs a device that can implement the above method, such as Figure 3 , 4 shown, which will include an infrared thermal imager 1, a laser ranging device 2, an ultrasonic wind speed and temperature measuring instrument 3, etc. For example, there is also a display screen 4. The device is built-in with an industrial control board, and the industrial control board can execute the method of Embodiment 1. Through this device, the wind speed, wind temperature of the real-time air flow and the temperature of the roadway surrounding rock, roadway size and other data can be measured on-site, and the possible occurrence location of rock burst can be judged according to the displayed stress magnitude, predicting the occurrence of disasters.

[0051] In the structure of this device, the function of the infrared thermal imager is to obtain the temperature distribution data on the surface of the roadway surrounding rock. The working principle of the infrared thermal imager is to use an infrared detector and an optical imaging objective lens to receive the infrared radiation energy distribution pattern of the measured target and reflect it onto the photosensitive element of the infrared detector, thereby obtaining an infrared thermal image. In this embodiment, the place where the temperature needs to be measured is intuitively displayed on the display screen, and the temperature value of each pixel can be read from the image, and then the measured temperature data is input into the chip of the industrial control board for calculation.

[0052] The laser ranging device is used to measure roadway size parameters such as roadway perimeter, roadway cross-sectional area, roadway hydraulic radius, and the measured wall surface area. After the measurement is completed, the industrial control board receives the detected size data in real time and performs calculations.

[0053] The ultrasonic wind speed and temperature measuring instrument consists of two parts of sensors, including an ultrasonic wind speed sensor and a temperature sensor. The temperature sensor is assembled inside the measuring instrument to detect the wind temperature data in real time. The ultrasonic wind speed and temperature measuring instrument can output wind speed and wind temperature data at the same time, and the industrial control board receives the detected data in real time and performs calculations.

[0054] This device is used in conjunction with a borehole temperature measurer, which mainly consists of a thermocouple, a platinum resistance, and a digital temperature sensor. After using a pneumatic drill to drill a hole, the original rock temperature and the temperature at a point in the surrounding rock mass of the roadway are measured in the borehole, and the measured data is displayed on the display screen of the temperature measurer, and the data is input into the industrial control board for calculation.

[0055] After the industrial control board calculates the temperature of the surrounding rock mass of the roadway affected by the air flow and the stress difference by calculating the temperature field of the surrounding rock mass of the roadway from the input data, it outputs the stress value of the surrounding rock mass of the roadway without air influence, conducts a rock burst risk analysis, comprehensively analyzes according to the stress distribution of the surrounding rock mass, calculates whether the rock burst risk reaches the threshold, and gives an evaluation result.

[0056] A specific actual operation process of this device is as follows:

[0057] (1) Turn on the infrared monitoring device for the stress of the rock roadway and enter the data acquisition mode;

[0058] (2) Input the previously known rock parameters (thermal conductivity, specific heat capacity, density, heat capacity) on the display screen;

[0059] (3) Click on the icon of the laser ranging module, align the laser sensor of this device directly at the object whose size needs to be measured, and let the laser sensor stand still for a period of time (about 15 seconds): measure the perimeter of the roadway, the cross-sectional area of the roadway, the hydraulic radius of the roadway, the roadway size parameters of the measured wall area, calculate the radius of the heat regulation circle, automatically input it, and display the size of the radius of the heat regulation circle on the display screen;

[0060] (4) According to the size of the heat regulation circle, use a pneumatic drill to drill a hole, install the temperature measurer in the hole, let it stand still for two minutes, measure the original rock temperature and the temperature at a point less than the radius of the heat regulation circle in the surrounding rock mass of the roadway, and display the measured data on the display screen of the temperature measurer, and manually input it on the display screen of the device;

[0061] (5) Click on the icon of the ultrasonic wind speed and temperature measurement module, hold the ultrasonic wind speed and temperature measurement device, and let it stand still for 30 seconds in the direction of the air flow to measure the wind speed and wind temperature at the location, display them on the display screen and automatically input them;

[0062] (6) Click to enter the calculation mode to automatically calculate the convective heat transfer coefficient, the heat flux density in the rock mass, then calculate the amount of heat exchanged between the surrounding rock wall of the roadway and the air flow, and use the heat and temperature conversion formula to calculate the change in the temperature of the surrounding rock mass of the roadway caused by the air flow;

[0063] (7) Click on the icon of the infrared temperature measurement module to turn on the infrared thermal imager in the device. The infrared thermal imaging camera of the device is directly facing the surrounding rock wall of the roadway. The device is left stationary for a period of time (about 30 seconds). The infrared temperature value of the current surrounding rock wall of the roadway will be displayed on the device's display screen, and the temperature influence of the air flow on the temperature of the wall will be automatically processed and subtracted to display the temperature field image of the surrounding rock wall of the roadway without the influence of wind, and the temperature value of each pixel of the temperature field image of the surrounding rock wall of the roadway will be automatically input;

[0064] (8) Click on the icon of the infrared temperature measurement module again. A small test block is placed in a windless area in the mine in advance, and the temperature value of the test block without stress influence under windless conditions is measured with the infrared thermal imager. Then calculate the average value and input the average temperature value;

[0065] (9) Click on the stress field calculation icon. Subtract the average infrared temperature value of the test block without stress influence from the temperature value of each pixel of the temperature field image of the surrounding rock wall of the roadway affected by stress, so as to obtain the magnitude of the stress tensor of each pixel, and display the stress field image of the surrounding rock wall of the roadway without the influence of wind in the form of an infrared temperature image;

[0066] (10) Finally, conduct rock burst assessment. Different stress values will obtain different warning messages, and the safety status of the surrounding rock of the roadway here can be judged according to the warning messages.

[0067] In summary, calculating the heat exchange amount between the surrounding rock of the roadway and the air flow is a very complex topic because the heat exchange changes with time and the rock formation is anisotropic. The traditional classical calculation method requires a large amount of numerical calculations and is a mathematical model established under many simplified and assumed conditions, and the calculation results are not necessarily reliable. The present invention estimates the change value of the heat flux density of the roadway wall surface by measuring the change value of the internal temperature of the surrounding rock of the roadway. According to the heat flux density, the magnitude of the heat transfer amount can be obtained, and then the calculation relationship between the heat transfer amount between the surrounding rock of the roadway and the air flow and the temperature change value of one or several points of the surrounding rock is calculated, so as to obtain how much influence the air flow in the roadway has on the temperature of the surrounding rock of the roadway, and then remove the influence of the air flow on the temperature of the surrounding rock of the roadway, leaving only the temperature change caused by the deformation of the surrounding rock of the roadway due to stress.

[0068] In addition, the present invention also designs a device for directly observing the stress condition of the roadway surrounding rock. At present, the coupled thermodynamics numerical research on simulating the temperature field change caused by rock deformation is still relatively rare. There has not yet been a device that can calculate the stress field from the temperature field of the roadway surrounding rock, and there is even no device that can directly observe the stress field of the roadway surrounding rock. Based on the temperature field of the roadway surrounding rock after removing the influence of the air flow, combined with the coupled thermodynamics of the temperature field change caused by rock deformation, the present invention uses the relationship between the temperature field change and the stress field obtained from the elastic thermal effect during the deformation process of the roadway surrounding rock, thereby providing a more novel, reliable and practical calculation method, and integrating it into a device for detecting the stress of the roadway surrounding rock based on infrared thermal imaging technology and removing the influence of the air flow through software and hardware design, so as to predict the occurrence of rock bursts.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An infrared monitoring method for roadway stress to solve the influence of air flow, characterized in that The method includes the following steps: Step S1: Obtain the thermophysical coefficients of the surrounding rock of the roadway and the roadway dimension parameters; Step S2: Calculate the radius of the heat-adjusting circle, and combine the original rock temperature and the temperature measurement value of a temperature measurement point in the surrounding rock of the roadway to calculate the heat flux density of the final roadway surrounding rock wall surface, and then obtain the heat of the heat exchange between the air flow and the roadway surrounding rock; Step S3: Calculate the temperature change value of the air flow on the temperature field of the roadway surrounding rock according to the corresponding relationship between heat and temperature; Step S4: By measuring the temperature values of each pixel of the infrared temperature field of the roadway surrounding rock wall surface affected by the air flow and stress, and combining the temperature change value, finally obtain the infrared temperature field image of the roadway surrounding rock wall surface affected only by stress without air flow; Step S5: Obtain the average temperature value of the specimen without air flow and not affected by stress, calculate the difference between each pixel of the infrared temperature field image of the roadway surrounding rock wall surface and the average temperature value of the specimen, then calculate the change of the stress tensor of each pixel point, and finally convert it into the stress value of each pixel point.

2. The roadway stress infrared monitoring method for solving the influence of air flow as described in claim 1, characterized in that In Step S1, the thermophysical coefficients include thermal conductivity λ, specific heat C, density ρ, heat capacity Cρ, and thermal diffusivity α, and the roadway dimension parameters include the hydraulic radius r0 of the roadway and the measured wall surface area S.

3. The infrared monitoring method for roadway stress to solve the influence of air flow according to claim 2, characterized in that, In step S2, the radius of the heating circle rt = r0 + (r0 2 + 12αt) 1 / 2 , where the hydraulic radius of the roadway is r0, the thermal diffusivity is α, and the time required for borehole temperature measurement is t; the calculated heat flux density on the wall of the roadway surrounding rock is q, and the heat Q1 of heat exchange between the air flow and the roadway surrounding rock is obtained by multiplying the heat flux density q by the measured wall area S.

4. The roadway stress infrared monitoring method for solving the influence of air flow according to claim 3, characterized in that, In Step S3, the corresponding relationship between heat and temperature is Q1 = a(t2 - t1)*S, where t1 is the temperature value affected only by stress without air flow, t2 is the temperature value affected by stress with air flow, a is the convective heat transfer coefficient, S is the measured wall surface area, and (t2 - t1) is the temperature change value of the air flow on the temperature field of the roadway surrounding rock.

5. The roadway stress infrared monitoring method for solving the influence of air flow as described in claim 4, characterized in that, The specific process of Step S4 is as follows: Measure the temperature values of each pixel of the infrared temperature field of the roadway surrounding rock wall surface affected by the air flow and stress by an infrared thermal imager, and subtract the temperature change value (t2 - t1) from each pixel temperature value to obtain the infrared temperature field image of the roadway surrounding rock wall surface affected only by stress without air flow.

6. The infrared monitoring method for roadway stress to solve the influence of air flow as described in claim 5, characterized in that, In Step S5, the relationship between the rock temperature change and the change of the stress tensor is: T0i - T00 = -T00×a / (ρ*Cρ)×Δδkk where T0i is the pixel temperature value of the infrared temperature field image of the roadway surrounding rock wall surface affected only by stress without air flow, T00 is the average temperature value of the specimen without air flow and not affected by stress, a is the convective heat transfer coefficient, ρ is the density of the rock mass, Cρ is the heat capacity of the rock mass, and Δδkk is the change of the stress tensor.

7. An infrared monitoring device for roadway stress to solve the influence of air flow, characterized in that, The roadway stress infrared monitoring device includes an infrared thermal imager, a laser ranging device, and an ultrasonic wind speed and temperature measuring instrument. The roadway stress infrared monitoring device is also internally provided with an industrial control board, and the industrial control board is used to execute the roadway stress infrared monitoring method according to any one of claims 1-6.

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