Overlying strata migration model establishing method and monitoring system

Abstract

The invention provides an overlying strata migration model establishing method and a monitoring system. The overlying strata migration model establishing method comprises the steps of determining a key monitoring horizon and a to-be-monitored area; the method comprises the following steps: determining a drilling design, performing multi-point drilling on an underground to-be-measured area, arranging a measuring system in a drilled hole, performing data processing on data measured in the measuring system in real time, and generating an initial three-dimensional strata migration overlying strata three-dimensional model; establishing a first strata migration overlying strata three-dimensional model of the position where the measuring point is located and a second strata migration overlying strata three-dimensional model of the position where the emitter is located at different times; performing data processing on the first strata migration overlying strata three-dimensional model and the second strata migration overlying strata three-dimensional model by adopting a Bayesian fusion method, and continuously updating posterior probability density; and comparing the posterior probability densities of the two models, and finally obtaining the dynamic evolution three-dimensional model of the working face overlying strata deep migration at different times by adopting weighted average. The method and the system are simple, and the real migration condition of the overlying strata can be clearly known.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and in particular to a method for establishing an overburden migration model and a monitoring system. Background Art

[0002] During coal mining, coal seam voiding will cause the overlying rock strata to move and fill the void area. The movement and change of overlying rock is the source of disasters such as coal mine roof collapse and rock burst. Real-time monitoring of the movement status of deep, distant and high overlying rock is an important means to prevent disasters.

[0003] The following problems exist in the existing monitoring of overburden movement during coal mining: it is impossible to clearly understand the actual movement status of the overburden in real time, and when rock burst or mine pressure accidents occur in coal mines, it is impossible to grasp the main disaster-causing strata and disaster-causing structures of the overburden; it is impossible to effectively reveal the disaster mechanism of rock burst or mine pressure accidents induced by overburden movement in coal mines, resulting in coal mines facing the threat of production accidents.

[0004] In addition, the existing technology mostly adopts the method of conducting multi-point drilling measurements on the ground to complete the monitoring of the movement of overburden rocks. The ground monitoring process often has the following problems: the ground measuring station is greatly affected by severe weather such as exposure to the sun, heavy rain, strong wind, and dust. At the same time, due to the deep burial of the coal seam, long-term use of monitoring equipment such as wire ropes and damping rollers is prone to wear, affecting the accuracy; ground measuring hole drilling construction is difficult, and multiple measuring points are arranged in a single measuring hole. When the measuring hole collapses due to rock movement, multiple measuring points are easily damaged as a whole, resulting in monitoring failure, making it difficult to capture the complex displacement pattern of the overburden of the entire coal system. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To achieve the above object, the present invention proposes a method for establishing a cover rock migration model, comprising the following steps:

[0007] S1. According to the key layer theory, the drilling information and coal rock information of the monitoring area are collected and input into the dynamic evolution data analysis system of overburden migration to preliminarily determine the key monitoring layers and areas to be tested of overburden migration;

[0008] S2. Divide the entire tunnel into multiple monitoring areas according to a certain range, and plan the drilling positions towards the key monitoring layers and the areas to be measured and the depth of each borehole in each monitoring area, and carry out drilling arrangement operations. After the drilling is completed, a measurement system connected to the ground monitoring center is arranged in each borehole;

[0009] S3, input the drilling information of each monitoring area into the overburden migration dynamic evolution data analysis system again to generate an initial three-dimensional rock migration overburden stereoscopic model;

[0010] S4. The measurement system includes a low-frequency electromagnetic wave transmitter for transmitting low-frequency electromagnetic waves and an in-hole measurement device for monitoring the physical quantity of rock stratum migration. In each monitoring area, low-frequency electromagnetic wave monitoring and rock stratum migration physical quantity monitoring are performed on the deep rock strata in multiple boreholes at different positions and depths. Combined with the initial three-dimensional rock stratum migration and overburden stratum stereoscopic model, a first rock stratum migration and overburden stratum stereoscopic model of the stratum where the measuring point is located at different times and a second rock stratum migration and overburden stratum stereoscopic model of the stratum where the low-frequency electromagnetic wave transmitter is located are established;

[0011] S5. Use the Bayesian fusion method to process the data of the first rock layer migration and overburden stereoscopic model and the second rock layer migration and overburden stereoscopic model, determine the prior data based on historical experience, and continuously update the posterior probability density; compare the posterior probability densities of the two models, evaluate the relative credibility, and select the model with the highest posterior probability density as the first-level optimal model for the current monitoring area;

[0012] S6. Analyze the data of the first-level optimization model of the adjacent monitoring areas, determine the weight index, and use the weighted average method to weighted average the prediction results of the first-level optimization models of the two adjacent monitoring areas. Compare and select the second-level optimization model that is more in line with the migration of overburden in the two adjacent monitoring areas. Weighted average the second-level optimization model and the first-level optimal model of the next adjacent monitoring area. Update the second-level optimization model through the weighted average method, and continuously weighted compare the first-level optimization models obtained in all monitoring areas in sequence, and finally obtain a three-dimensional model of the dynamic evolution of the deep migration of overburden in the working face at different times.

[0013] After determining the monitoring layer and the area to be tested by the key layer theory, the present invention performs multi-point drilling monitoring on the deep overburden of the area to be tested, establishes a first rock layer migration overburden stereo model and a second rock layer migration overburden stereo model according to the monitoring results, and continuously updates the posterior probability density of the first rock layer migration overburden stereo model and the second rock layer migration overburden stereo model in combination with the Bayesian fusion method, selects the model with the highest posterior probability density as the primary optimal model of the current monitoring area, and adopts the weighted average method to perform weighted average on the primary optimal models of adjacent monitoring areas. , a secondary optimization model is obtained by optimization, and the secondary optimization model is weighted averaged with the primary optimization model of the next monitoring area again, and the secondary optimization model is updated by optimization, and finally a three-dimensional model of the dynamic evolution of the deep movement of the overburden in the working face at different times is obtained, and the model is continuously verified and optimized in combination with the monitoring data, and finally the accurate tracking of the movement of the measuring points is achieved, so as to understand the real migration status of the overburden strata and grasp the main disaster-causing strata and disaster-causing structures of the overburden when rock burst or mine pressure accidents occur in coal mines, and reveal the disaster mechanism of rock burst or mine pressure accidents induced by overburden movement in coal mines.

[0014] Optionally, in S1, the key monitoring layer is determined according to the key layer theory; the area to be measured is an area where rock burst or mine pressure disasters occur and an area to be measured, which is determined according to the mine geological conditions and mining technical conditions;

[0015] Among them, the potential occurrence areas of rock burst and mine pressure disasters are determined based on the maximum daily energy and number of vibrations obtained by the microseismic monitoring system. In coal seams with impact tendency, the areas where mine earthquakes greater than 104J occur four or more times a day are determined as potential occurrence areas of rock burst. In coal seams without impact tendency, the areas where vibrations greater than 103J occur three or more times a day are determined as potential occurrence areas of mine pressure disasters. The areas that need to be measured are determined based on the actual needs of the mine.

[0016] Furthermore, in the S1, the borehole information collected in the monitoring area includes the borehole columnar information, and the coal rock information in the monitoring area includes the coal rock physical and mechanical property information. The borehole columnar information and the coal rock physical and mechanical property information are input into the overburden migration dynamic evolution data analysis system to generate key layers and fracture distances, which are combined with the three-zone height empirical formula to determine the key monitoring layers and the area to be measured for overburden migration; the three zones include the collapse zone, the water-conducting fracture zone, and the curved subsidence zone. The monitoring layers determined in S1 only involve the collapse zone and the water-conducting fracture zone, and their height empirical formulas are as follows:

[0017] Empirical formula for collapse zone height:

[0018]

[0019] Empirical formula for water-conducting fracture zone height:

[0020]

[0021] Furthermore, in S3, multi-point drilling operations are performed when drilling in the area to be tested underground. By setting up a measurement system in the boreholes at multiple points, the drilling information of multiple points is transmitted to the ground monitoring center, and the initial spatial relationship collected by the measuring device is set in the three-dimensional positioning software to establish a multi-point three-dimensional positioning field, and use the borehole column eye shape to generate an initial three-dimensional rock stratum migration overburden stereoscopic model.

[0022] Further, the measurement system includes an in-hole measurement device and an external data acquisition and processing component;

[0023] The in-hole measuring device comprises a steel anchor claw rod body, a low-frequency electromagnetic wave transmitter, an accelerometer, a gyroscope, an anchor plug and the steel anchor claw rod body are arranged inside the steel anchor claw rod body, and the end of the steel anchor claw rod body is filled with solidification slurry for sealing;

[0024] The external data acquisition and processing components include accelerometer and gyroscope data acquisition instruments, low-frequency electromagnetic wave receiving systems, displacement monitoring components, and wireless acquisition substations;

[0025] The in-hole measuring device sends the measurement data of the accelerometer, low-frequency electromagnetic wave transmitter and gyroscope to the collector corresponding to the external data acquisition and processing component through a wired connection or a communication connection, and a displacement monitoring cable for measuring the displacement of the steel anchor claw rod body is connected between the steel anchor claw rod body and the displacement monitoring component.

[0026] Furthermore, the end of the displacement monitoring cable is connected to a naturally drooping balance hammer after passing through a group of guide wheels, and the displacement monitoring cable is kept in a tensioned state through the balance hammer. The displacement monitoring component includes a pull-wire displacement data collector for monitoring the movement of the displacement monitoring cable.

[0027] Furthermore, in step S4, during data processing, a positioning algorithm based on the low-frequency electromagnetic wave receiving interval time and attenuation index is used to determine the second stratum migration overburden stereoscopic model, and combined with the data measured by the measuring point accelerometer, gyroscope, and wire-type displacement data acquisition instrument, the stratum displacement angle and displacement amount data are calculated to determine the first stratum migration overburden stereoscopic model:

[0028] The formula for converting angular velocity to angle is:

[0029] Where θ(t) is the angle at time t, ω(t') is the angular velocity at time t', which is achieved by accumulating the angular velocity changes between adjacent data points;

[0030] Acceleration to displacement conversion formula:

[0031] Where v(t) is the velocity at time t, s(t) is the displacement at time t, and a(t') is the acceleration at time t'. The influence of gravity must be removed first to perform tilt correction.

[0032] Furthermore, in S5, when the Bayesian fusion method is used for data processing, the calculation method for updating the posterior probability density is as follows:

[0033]

[0034] Where P(θ / D) is the posterior probability density, P(D / θ) is the likelihood function, P(θ) is the prior probability density, and P(D) is the marginal probability of the data.

[0035] Furthermore, in S6, the factors affecting the weight index include roof lithology type, ground stress direction, mining depth, and coal seam mining thickness.

[0036] The present invention also provides a monitoring system for overburden migration model, characterized in that it comprises a borehole arranged on the side wall of the tunnel, the borehole is arranged toward the area to be monitored, an in-hole measuring device is arranged in the borehole, and an external data acquisition and processing component is arranged near the opening of the borehole in the tunnel;

[0037] The in-hole measuring device comprises a steel anchor rod body arranged near the position of the area to be measured, and a monitoring component is arranged inside the steel anchor rod body;

[0038] The external data acquisition and processing component includes a plurality of acquisition instruments for acquiring information of the monitoring component, and a displacement monitoring component suspended on the top wall of the tunnel, the displacement monitoring component is used to monitor the displacement of the rock formation, a wired electrical connection is set between the plurality of acquisition instruments and the monitoring component, and a displacement monitoring steel cable for monitoring the displacement is set between the monitoring component and the displacement monitoring component;

[0039] A monitoring center is arranged on the ground and is wirelessly connected to the external data acquisition and processing components.

[0040] Furthermore, the monitoring component includes a low-frequency electromagnetic wave micro-transmitter, an accelerometer, a gyroscope and an anchoring plug; the multiple collectors include an accelerometer and gyroscope data collector, a low-frequency electromagnetic wave receiving system and a wireless collection substation, the accelerometer and gyroscope data collector is electrically connected to the accelerometer and gyroscope, the low-frequency electromagnetic wave receiving system is used to receive electromagnetic waves from the low-frequency electromagnetic wave micro-transmitter, and the wireless collection substation is used to transmit monitoring information to a ground monitoring center.

[0041] Furthermore, the displacement monitoring assembly includes a fixed plate arranged on the top wall of the tunnel, a pull-wire displacement data collector is suspended on the bottom wall of the fixed plate, a guide wheel is suspended on the fixed plate on the side facing the test end of the pull-wire displacement data collector, the displacement monitoring steel cable is arranged around the guide wheel, and a balance hammer is suspended at the end of the displacement monitoring steel cable, and the measuring end of the pull-wire data collector is connected to the guide wheel position corresponding to the displacement monitoring steel cable.

[0042] Furthermore, an anti-wear sleeve is provided at the drilling opening.

[0043] Furthermore, the anchor head diameter of the steel fluke rod body is set to be less than or equal to 2 / 3 of the hole diameter, and the anchor head is provided with barbs, and the outermost diameter of the barbs is 5 / 4 of the borehole diameter.

[0044] Furthermore, the connecting wires between the monitoring assembly and the multiple collectors are configured as self-supporting braided communication cables, and the ends of the in-hole monitoring data cables are configured perpendicular to the tunnel floor, with a verticality deviation of less than 1%.

[0045] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0047] Figure 1 A schematic diagram of the steps of a method for establishing a cover rock migration model according to the present invention;

[0048] Figure 2 The figure is a schematic diagram of the system layout of a cover rock migration model monitoring system according to the present invention.

[0049] Description of reference numerals:

[0050] 1. Drilling; 2. In-hole measuring device; 21. Steel anchor claw rod body; 22. Barb; 3. External data processing component; 31. Accelerometer and gyroscope data acquisition instrument; 32. Low-frequency electromagnetic wave receiving system; 33. Wireless acquisition substation; 4. Fixed plate; 5. Displacement monitoring component; 51. Pull-wire displacement data acquisition instrument; 52. Displacement monitoring steel cable; 53. Guide wheel; 54. Balance hammer; 6. Anti-wear sleeve; 7. Communication cable. DETAILED DESCRIPTION

[0051] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0052] The present invention provides a method for establishing a cover rock migration model. Figure 1 to Figure 2 Elaborate in detail.

[0053] A method for establishing an overburden migration model comprises the following steps:

[0054] S1. According to the key layer theory, the drilling information and coal rock information of the monitoring area are collected and input into the dynamic evolution data analysis system of overburden migration to preliminarily determine the key monitoring layers and areas to be tested of overburden migration;

[0055] S2. Divide the entire tunnel into multiple monitoring areas according to a certain range, and plan the drilling positions towards the key monitoring layers and the areas to be measured and the depth of each borehole in each monitoring area, and carry out drilling arrangement operations. After the drilling is completed, a measurement system connected to the ground monitoring center is arranged in each borehole;

[0056] S3, input the drilling information of each monitoring area into the overburden migration dynamic evolution data analysis system again to generate an initial three-dimensional rock migration overburden stereoscopic model;

[0057] S4. The measurement system includes a low-frequency electromagnetic wave transmitter for transmitting low-frequency electromagnetic waves and an in-hole measurement device for monitoring the physical quantity of rock stratum migration. In each monitoring area, low-frequency electromagnetic wave monitoring and rock stratum migration physical quantity monitoring are performed on the deep rock strata in multiple boreholes at different positions and depths. Combined with the initial three-dimensional rock stratum migration and overburden stratum stereoscopic model, a first rock stratum migration and overburden stratum stereoscopic model of the stratum where the measuring point is located at different times and a second rock stratum migration and overburden stratum stereoscopic model of the stratum where the low-frequency electromagnetic wave transmitter is located are established;

[0058] S5. Use the Bayesian fusion method to process the data of the first rock layer migration and overburden stereoscopic model and the second rock layer migration and overburden stereoscopic model, determine the prior data based on historical experience, and continuously update the posterior probability density; compare the posterior probability densities of the two models, evaluate the relative credibility, and select the model with the highest posterior probability density as the first-level optimal model for the current monitoring area;

[0059] S6. Analyze the data of the first-level optimization model of the adjacent monitoring areas, determine the weight index, and use the weighted average method to weighted average the prediction results of the first-level optimization models of the two adjacent monitoring areas. Compare and select the second-level optimization model that is more in line with the migration of overburden in the two adjacent monitoring areas. Weighted average the second-level optimization model and the first-level optimal model of the next adjacent monitoring area. Update the second-level optimization model through the weighted average method, and continuously weighted compare the first-level optimization models obtained in all monitoring areas in sequence, and finally obtain a three-dimensional model of the dynamic evolution of the deep migration of overburden in the working face at different times.

[0060] After determining the monitoring layer and the area to be tested by the key layer theory, the present invention performs multi-point drilling monitoring on the deep overburden of the area to be tested, establishes a first rock layer migration overburden stereo model and a second rock layer migration overburden stereo model according to the monitoring results, and continuously updates the posterior probability density of the first rock layer migration overburden stereo model and the second rock layer migration overburden stereo model in combination with the Bayesian fusion method, selects the model with the highest posterior probability density as the primary optimal model of the current monitoring area, and adopts the weighted average method to perform weighted average on the primary optimal models of adjacent monitoring areas. , a secondary optimization model is obtained by optimization, and the secondary optimization model is weighted averaged with the primary optimization model of the next monitoring area again, and the secondary optimization model is updated by optimization, and finally a three-dimensional model of the dynamic evolution of the deep movement of the overburden in the working face at different times is obtained, and the model is continuously verified and optimized in combination with the monitoring data, and finally the accurate tracking of the movement of the measuring points is achieved, so as to understand the real migration status of the overburden strata and grasp the main disaster-causing strata and disaster-causing structures of the overburden when rock burst or mine pressure accidents occur in coal mines, and reveal the disaster mechanism of rock burst or mine pressure accidents induced by overburden movement in coal mines.

[0061] In one embodiment, in S1, the key monitoring layer is determined according to the key layer theory; the area to be measured is the area where rock burst or mine pressure disaster occurs and the area to be measured, which is determined according to the mine geological conditions and mining technical conditions;

[0062] Among them, the potential occurrence areas of rock burst and mine pressure disasters are determined based on the maximum daily energy and number of vibrations obtained by the microseismic monitoring system. In coal seams with impact tendency, the areas where mine earthquakes greater than 104J occur four or more times a day are determined as potential occurrence areas of rock burst. In coal seams without impact tendency, the areas where vibrations greater than 103J occur three or more times a day are determined as potential occurrence areas of mine pressure disasters. The areas that need to be measured are determined based on the actual needs of the mine.

[0063] In one embodiment, in S1, the borehole information collected in the monitoring area includes the borehole columnar information, and the coal rock information in the monitoring area includes the coal rock physical and mechanical property information. The borehole columnar information and the coal rock physical and mechanical property information are input into the overburden migration dynamic evolution data analysis system to generate key layers and fracture distances, which are combined with the three-zone height empirical formula to determine the key monitoring layers and the area to be tested for overburden migration; the three zones include the collapse zone, the water-conducting fracture zone, and the curved subsidence zone. The monitoring layers determined in S1 only involve the collapse zone and the water-conducting fracture zone, and their height empirical formulas are as follows:

[0064] Empirical formula for collapse zone height:

[0065]

[0066] Empirical formula for water-conducting fracture zone height:

[0067]

[0068] In one embodiment, in S2, multi-point drilling is performed when drilling in the area to be tested underground, and anti-wear sleeves are installed in the boreholes to prevent the communication cable from being broken due to friction.

[0069] In one embodiment, the measurement system includes an in-hole measurement device and an external data acquisition and processing component;

[0070] The in-hole measuring device comprises a steel anchor claw rod body, a low-frequency electromagnetic wave transmitter, an accelerometer, a gyroscope, an anchor plug and the steel anchor claw rod body are arranged inside the steel anchor claw rod body, and the end of the steel anchor claw rod body is filled with solidification slurry for sealing;

[0071] The external data acquisition and processing components include accelerometer and gyroscope data acquisition instruments, low-frequency electromagnetic wave receiving systems, displacement monitoring components, and wireless acquisition substations;

[0072] The in-hole measuring device sends the measurement data of the accelerometer, low-frequency electromagnetic wave transmitter and gyroscope to the collector corresponding to the external data acquisition and processing component through a wired connection or a communication connection, and a displacement monitoring cable for measuring the displacement of the steel anchor claw rod body is connected between the steel anchor claw rod body and the displacement monitoring component, and a communication cable connects the in-hole measuring device to the external data acquisition and processing component.

[0073] The following is an explanation of the operating principle of the monitoring device in S3.

[0074] The in-hole measuring device utilizes the low-frequency electromagnetic wave positioning technology of the three-dimensional field and the mechanical three-dimensional space displacement and angle rotation positioning technology. The low-frequency electromagnetic wave micro-transmitter and the mechanical three-dimensional space displacement and angle rotation measurement system (including accelerometer, gyroscope, anchor plug) are installed inside the steel anchor claw rod body, finally forming an in-hole measuring device and fixing it to the overlying rock formation of the working face (tunnel).

[0075] After the three-dimensional spatial displacement and angle rotation receiving system in the tunnel is connected and stabilized with the measuring system, the acceleration, angular velocity and displacement data of the measuring point relative to the hole mouth are transmitted in real time. The low-frequency electromagnetic wave receiving system in the tunnel is connected with the transmitter to receive signals through electromagnetic waves in real time. By setting the initial spatial relationship between the in-hole measuring device and the tunnel receiving system in the three-dimensional positioning software, a multi-point three-dimensional positioning field is established, and the original three-dimensional overburden stereo model is generated using the drilling column lithology.

[0076] When the monitored overlying rock strata are disturbed by mining and move, the rock strata will cause three-dimensional movement. The low-frequency electromagnetic wave positioning system will transmit the signal interval time, attenuation and other data between the transmitter and the receiver in real time. The mechanical three-dimensional space displacement and angle rotation positioning system will transmit the received relative displacement, acceleration, angular velocity and other data in real time.

[0077] The angular velocity, acceleration and relative displacement data monitored by the multi-point mechanical three-dimensional spatial displacement and angle rotation positioning system are analyzed. The accelerometer can obtain the acceleration signals of the three independent axes of the coordinate system. The gyroscope can separate the gravity acceleration and the carrier motion acceleration to provide a reference coordinate system for the accelerometer, that is, the pitch (X axis), roll (Y axis) and yaw (Z axis) that can be measured, and the velocity, displacement angle and displacement of the rock layer at the measuring point layer are obtained. The measuring point data of multiple measuring holes are coupled to determine the position and direction of the measuring point in three-dimensional space, and establish a three-dimensional model of the migration of the first rock layer and the overburden at the measuring point layer at different times;

[0078] The ground monitoring center receives downhole data in real time and, based on the key layer theory, uses a positioning algorithm to process the data collected by multi-point low-frequency electromagnetic wave transmitters in multi-point boreholes to establish a three-dimensional model of the migration of the second rock layer at the layer where the transmitter is located at different times.

[0079] In one embodiment, the end of the displacement monitoring cable is connected to a naturally drooping balance hammer after passing around a group of guide wheels, and the displacement monitoring cable is kept in a tensioned state through the balance hammer. The displacement monitoring component includes a pull-wire displacement data collector for monitoring the movement of the displacement monitoring cable.

[0080] In one embodiment, in step S4, when processing data, a positioning algorithm based on the low-frequency electromagnetic wave receiving interval time and attenuation index is used to determine the second rock layer migration overburden three-dimensional model, and combined with the data measured by the measuring point accelerometer, gyroscope, and wire-type displacement data acquisition instrument, the rock layer displacement angle and displacement amount data are calculated to determine the first rock layer migration overburden three-dimensional model, wherein:

[0081] The formula for converting angular velocity to angle is:

[0082] Where θ(t) is the angle at time t, ω(t') is the angular velocity at time t', which is achieved by accumulating the angular velocity changes between adjacent data points;

[0083] Acceleration to displacement conversion formula:

[0084] Where v(t) is the velocity at time t, s(t) is the displacement at time t, and a(t') is the acceleration at time t'. The influence of gravity must be removed first to perform tilt correction.

[0085] In one embodiment, in S5, when the Bayesian fusion method is used for data processing, the calculation method for updating the posterior probability density is as follows:

[0086]

[0087] Where P(θ / D) is the posterior probability density, P(D / θ) is the likelihood function, P(θ) is the prior probability density, and P(D) is the marginal probability of the data.

[0088] The Bayesian fusion method is used to treat the first rock layer migration overburden stereo model and the second rock layer migration overburden stereo model as prior models, and the posterior probability density is continuously updated. In step S5, the weighted average method is used to determine the weight index, and the prediction results of the two models are weighted averaged to finally obtain the dynamic evolution stereo model of the deep migration of the overburden of the working face (tunnel) at different times, and it is continuously verified and optimized. Accurate tracking of the migration of the measuring points is achieved, so as to understand the real migration status of the overburden and grasp the main disaster-causing layer and disaster-causing structure of the overburden when rock burst or mine pressure accidents occur in coal mines, revealing the disaster mechanism of rock burst or mine pressure accidents induced by overburden movement in coal mines.

[0089] Furthermore, in S5, the weights should be determined based on historical data, expert experience, and the accuracy of model predictions. The two models should be assigned corresponding weights. The factors affecting the weight index include roof lithology type, ground stress direction, mining depth, and coal seam mining thickness.

[0090] The present invention also provides a monitoring system for overburden migration model, as shown below Figure 2 Elaborate in detail.

[0091] A monitoring system for overburden migration model includes a borehole arranged on the side wall of a tunnel, the borehole is arranged toward the area to be monitored, an in-hole measuring device is arranged in the borehole, and an external data acquisition and processing component is arranged near the opening of the borehole in the tunnel;

[0092] The in-hole measuring device comprises a steel anchor claw rod body arranged near the position of the area to be measured, and a monitoring component is arranged inside the steel anchor claw rod body;

[0093] The external data acquisition and processing component includes a plurality of acquisition instruments for acquiring information of the monitoring component, and a displacement monitoring component suspended on the top wall of the tunnel, the displacement monitoring component is used to monitor the displacement of the rock formation, a wired electrical connection is set between the plurality of acquisition instruments and the monitoring component, and a displacement monitoring steel cable for monitoring the displacement is set between the monitoring component and the displacement monitoring component;

[0094] A monitoring center is arranged on the ground and is wirelessly connected to the external data acquisition and processing components.

[0095] In some embodiments, the monitoring component includes a low-frequency electromagnetic wave micro-transmitter, an accelerometer, a gyroscope and an anchoring plug; multiple collectors include an accelerometer and gyroscope data collector, a low-frequency electromagnetic wave receiving system and a wireless collection substation, the accelerometer and gyroscope data collector is electrically connected to the accelerometer and gyroscope, the low-frequency electromagnetic wave receiving system is used to receive the electromagnetic waves of the low-frequency electromagnetic wave micro-transmitter, and the wireless collection substation is used to transmit monitoring information to the ground monitoring center.

[0096] In one embodiment, the displacement monitoring assembly includes a fixed plate arranged on the top wall of the tunnel, a pull-wire displacement data collector is suspended on the bottom wall of the fixed plate, a guide wheel is suspended on the fixed plate on the side facing the test end of the pull-wire displacement data collector, the displacement monitoring steel cable is arranged around the guide wheel, and a balance hammer is suspended at the end of the displacement monitoring steel cable, and the measuring end of the pull-wire data collector is connected to the guide wheel position corresponding to the displacement monitoring steel cable.

[0097] In some embodiments, in order to prevent the connection line between the measuring device and the collector and the displacement monitoring cable from being worn or broken due to long-term friction at the hole mouth, an anti-wear sleeve is provided at the borehole opening.

[0098] In some embodiments, in order to ensure that the steel anchor rod body can be inserted into the drilled hole and can be stably fixed in the drilled hole, the anchor head diameter of the steel anchor claw rod body is set to be less than or equal to 2 / 3 of the hole diameter, and a barb is provided on the anchor head, and the outermost diameter of the barb is 5 / 4 of the drilled hole diameter.

[0099] In some embodiments, the connecting wires between the monitoring component and the multiple collectors, that is, the communication cable connecting the in-hole measurement device and the external data acquisition and processing component, are set as self-supporting braided communication cables. The self-supporting steel wire braided communication cable refers to a cable harness wrapped around a central reinforced flexible rod, tightly wrapped by a steel wire braid, and wrapped with a steel wire rope with a diameter of >0.6mm on the outermost side, with a tensile strength of >1770MPa, 304 stainless steel material, and a left-twist type;

[0100] In addition, the end of the in-hole monitoring data line is arranged perpendicular to the tunnel floor, and the verticality deviation is less than 1%.

[0101] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0102] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0103] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0104] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0105] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0106] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for establishing an overburden migration model, characterized in that: The following steps are involved: S1. According to the key layer theory, the drilling information and coal rock information of the monitoring area are collected and input into the dynamic evolution data analysis system of overburden migration to preliminarily determine the key monitoring layers and areas to be tested of overburden migration; S2. Divide the entire tunnel into multiple monitoring areas according to a certain range, and plan the drilling positions towards the key monitoring layers and the areas to be measured and the depth of each borehole in each monitoring area, and carry out drilling arrangement operations. After the drilling is completed, a measurement system connected to the ground monitoring center is arranged in each borehole; S3, input the drilling information of each monitoring area into the overburden migration dynamic evolution data analysis system again to generate an initial three-dimensional rock migration overburden stereoscopic model; S4. The measurement system includes a low-frequency electromagnetic wave transmitter for transmitting low-frequency electromagnetic waves and an in-hole measurement device for monitoring the physical quantity of rock stratum migration. In each monitoring area, low-frequency electromagnetic wave monitoring and rock stratum migration physical quantity monitoring are performed on the deep rock strata in multiple boreholes at different positions and depths. Combined with the initial three-dimensional rock stratum migration and overburden stratum stereoscopic model, a first rock stratum migration and overburden stratum stereoscopic model of the stratum where the measuring point is located at different times and a second rock stratum migration and overburden stratum stereoscopic model of the stratum where the low-frequency electromagnetic wave transmitter is located are established; S5. Use the Bayesian fusion method to process the data of the first rock layer migration and overburden stereoscopic model and the second rock layer migration and overburden stereoscopic model, determine the prior data based on historical experience, and continuously update the posterior probability density; compare the posterior probability densities of the two models, evaluate the relative credibility, and select the model with the highest posterior probability density as the first-level optimal model for the current monitoring area; S6. Analyze the data of the first-level optimization model of the adjacent monitoring areas, determine the weight index, and use the weighted average method to weighted average the prediction results of the first-level optimization models of the two adjacent monitoring areas. Compare and select the second-level optimization model that is more in line with the migration of overburden in the two adjacent monitoring areas. Weighted average the second-level optimization model and the first-level optimal model of the next adjacent monitoring area. Update the second-level optimization model through the weighted average method, and continuously weighted compare the first-level optimization models obtained in all monitoring areas in sequence, and finally obtain a three-dimensional model of the dynamic evolution of the deep migration of overburden in the working face at different times.

2. A method for establishing a cover rock migration model according to claim 1, characterized in that: In S1, the key monitoring layer is determined according to the key layer theory; the area to be measured is the area with rock burst or mine pressure disasters and the area to be measured determined according to the mine geological conditions and mining technical conditions; The potential occurrence areas of rock burst and mine pressure disasters are determined based on the maximum daily energy and vibration times obtained by the microseismic monitoring system. In coal seams with rock burst tendency, the potential occurrence areas of rock burst and mine pressure disasters are determined based on the maximum daily energy and vibration times obtained by the microseismic monitoring system. 4 The J mine earthquake area is determined as a potential rock burst area. In coal seams without rock burst tendency, there are 3 or more rock bursts in a single day. 3 The J vibration area is determined as the potential area for mining pressure disasters, and the area that needs to be measured is determined based on the actual needs of the mine.

3. The method for establishing a cover rock migration model according to claim 1, characterized in that: In the S1, the borehole information of the monitoring area includes the borehole columnar information, and the coal and rock information of the monitoring area includes the physical and mechanical property information of the coal and rock. The borehole columnar information and the physical and mechanical property information of the coal and rock are input into the overburden migration dynamic evolution data analysis system to generate key layers and fracture distances, which are combined with the three-zone height empirical formula to determine the key monitoring layers and the area to be measured for overburden migration; the three zones include the collapse zone, the water-conducting fracture zone and the curved subsidence zone. The monitoring layers determined in S1 only involve the collapse zone and the water-conducting fracture zone, and their height empirical formulas are as follows: Empirical formula for collapse zone height: Empirical formula for water-conducting fracture zone height:

4. A method for establishing a cover rock migration model according to claim 3, characterized in that: In the S3, multi-point drilling operations are performed when drilling in the area to be measured underground. By setting up a measurement system in the boreholes at multiple points, the drilling information of multiple points is transmitted to the ground monitoring center, and the initial spatial relationship collected by the measuring device is set in the three-dimensional positioning software to establish a multi-point three-dimensional positioning field, and the initial three-dimensional rock stratum migration overburden stereoscopic model is generated using the borehole column chart lithology.

5. The method for establishing a cover rock migration model according to claim 1, characterized in that: The measurement system includes an in-hole measurement device and an external data acquisition and processing component; The in-hole measuring device comprises a steel anchor claw rod body, a low-frequency electromagnetic wave transmitter, an accelerometer, a gyroscope, an anchor plug and the steel anchor claw rod body are arranged inside the steel anchor claw rod body, and the end of the steel anchor claw rod body is filled with solidification slurry for sealing; The data acquisition and processing components include accelerometer and gyroscope data acquisition instruments, low-frequency electromagnetic wave receiving systems, displacement monitoring components, and wireless acquisition substations; The in-hole measuring device sends the measurement data of the accelerometer, low-frequency electromagnetic wave transmitter and gyroscope to the collector corresponding to the data acquisition and processing component through a wired connection or a communication connection, and a displacement monitoring cable for measuring the displacement of the steel anchor claw rod body is connected between the steel anchor claw rod body and the displacement monitoring component.

6. A method for establishing a cover rock migration model according to claim 5, characterized in that: The end of the displacement monitoring cable is connected to a naturally drooping balance hammer after passing through a set of guide wheels. The balance hammer is used to keep the displacement monitoring cable in a tensioned state. The displacement monitoring component includes a pull-wire displacement data acquisition instrument for monitoring the movement of the displacement monitoring cable.

7. A method for establishing a cover rock migration model according to claim 6, characterized in that: In step S4, when processing data, a positioning algorithm based on the interval time and attenuation index of low-frequency electromagnetic wave reception is used to determine the three-dimensional model of the migration and overburden of the second rock layer, and combined with the data measured by the measuring point accelerometer, gyroscope, and wire-type displacement data acquisition instrument, the displacement angle and displacement amount data of the rock layer are calculated to determine the three-dimensional model of the migration and overburden of the second rock layer: The formula for converting angular velocity to angle is: Where θ(t) is the angle at time t, ω(t') is the angular velocity at time t', which is achieved by accumulating the angular velocity changes between adjacent data points; Acceleration to displacement conversion formula: Where v(t) is the velocity at time t, s(t) is the displacement at time t, and a(t') is the acceleration at time t'. The influence of gravity must be removed first to perform tilt correction.

8. The method for establishing a cover rock migration model according to claim 1, characterized in that: In S5, when the Bayesian fusion method is used for data processing, the calculation method for updating the posterior probability density is as follows: Where P(θ / D) is the posterior probability density, P(D / θ) is the likelihood function, P(θ) is the prior probability density, and P(D) is the marginal probability of the data.

9. The method for establishing a cover rock migration model according to claim 1, characterized in that: In S6, the factors affecting the weight index include roof lithology type, ground stress direction, mining depth, and coal seam mining thickness.

10. A monitoring system for overburden migration model, characterized in that: It includes a borehole arranged on the side wall of the tunnel, the borehole is arranged toward the area to be monitored, and an in-hole measuring device is arranged in the borehole, and an external data acquisition and processing component is arranged near the opening of the borehole in the tunnel; The in-hole measuring device comprises a steel anchor rod body arranged near the position of the area to be measured, and a monitoring component is arranged inside the steel anchor rod body; The external data acquisition and processing component includes a plurality of acquisition instruments for acquiring information of the monitoring component, and a displacement monitoring component suspended on the top wall of the tunnel, the displacement monitoring component is used to monitor the displacement of the rock formation, a wired electrical connection is set between the plurality of acquisition instruments and the monitoring component, and a displacement monitoring steel cable for monitoring the displacement is set between the monitoring component and the displacement monitoring component; A monitoring center is arranged on the ground and is wirelessly connected to the external data acquisition and processing components.

11. The overburden migration model monitoring system according to claim 10, characterized in that: The monitoring component includes a low-frequency electromagnetic wave micro-transmitter, an accelerometer, a gyroscope and an anchoring plug; the multiple collectors include an accelerometer and gyroscope data collector, a low-frequency electromagnetic wave receiving system and a wireless collection substation, the accelerometer and gyroscope data collector is electrically connected to the accelerometer and gyroscope, the low-frequency electromagnetic wave receiving system is used to receive the electromagnetic waves of the low-frequency electromagnetic wave micro-transmitter, and the wireless collection substation is used to transmit monitoring information to a ground monitoring center.

12. The overburden migration model monitoring system according to claim 10, characterized in that: The displacement monitoring assembly includes a fixed plate arranged on the top wall of the tunnel, a pull-wire displacement data collector is suspended on the bottom wall of the fixed plate, a guide wheel is suspended on the fixed plate on the side facing the test end of the pull-wire displacement data collector, the displacement monitoring steel cable is arranged around the guide wheel, and a balance hammer is suspended at the end of the displacement monitoring steel cable, and the measuring end of the pull-wire data collector is connected to the guide wheel position corresponding to the displacement monitoring steel cable.

13. The overburden migration model monitoring system according to claim 10, characterized in that: An anti-wear sleeve is arranged at the drilling opening.

14. The overburden migration model monitoring system according to claim 10, characterized in that: The anchor head diameter of the steel fluke rod body is set to be less than or equal to 2 / 3 of the hole diameter, and the anchor head is provided with barbs, and the outermost diameter of the barbs is 5 / 4 of the borehole diameter.

15. The overburden migration model monitoring system according to any one of claims 10 to 14, characterized in that: The connecting wires between the monitoring assembly and the plurality of collectors are arranged as self-supporting braided communication cables, and the ends of the in-hole monitoring data cables are arranged perpendicular to the tunnel floor, and the verticality deviation is less than 1%.

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