CN-121997806-A - Mine return air corner hypoxia multi-source tracing method and early warning system

CN121997806ACN 121997806 ACN121997806 ACN 121997806ACN-121997806-A

Abstract

The invention discloses a mine return air corner hypoxia multi-source tracing method and an early warning system, wherein the method comprises the following steps of measuring parameters of a coal bed and physical and mechanical parameters of a coal stratum; the method comprises the steps of measuring isotope values of coal bed gases, establishing an end member gas characteristic database, establishing a physical similarity simulation experiment model, simulating a mine environment to carry out coal bed exploitation experiments, calculating diversion capacity and weight coefficients of overburden cracks, screening out two groups of isotope indexes with the largest distinction degree from the database, inputting the two groups of isotope indexes, the diversion capacity and the weight coefficients into a multi-end member mixing equation to obtain mixed isotope values, analyzing sources and flow paths based on concentration, flow velocity and flow paths of the gases, constructing a numerical model, comparing the numerical model with field data, and predicting and early warning the concentration and the flow velocity of the gases of the source tracing sources. The method and the device remarkably improve the accuracy and reliability of gas tracing, realize the prediction and early warning of gas sources and migration paths, and remarkably improve the advance and comprehensiveness of hypoxia risk identification.

Inventors

ZOU QUANLE
XU KE
Ran Qican
LIANG YUNPEI
LIU YING
HONG LEI
LI TENGLONG
MA YAHUI

Assignees

重庆大学

Dates

Publication Date: 20260508
Application Date: 20251230

Claims (10)

1. The multi-source tracing method for the air return corner air of the fully mechanized mining face is characterized by comprising the following steps of: S1, through geological exploration, the geological structures of a shearable layer and adjacent coal strata are counted, relevant geological information is recorded, and parameters of each coal bed, physical and mechanical parameters of the coal strata and geometric shapes of the coal beds and the coal strata are measured; s2, constructing a mine, and measuring the gas content, ventilation condition, temperature, gas pressure and coal bed gas components in the mine; s3, measuring isotope values of the coal bed gases, and establishing an end member gas characteristic database; S4, determining a similarity ratio of a physical similarity simulation experiment based on the coal bed parameters and the coal stratum physical mechanical parameters, and building a physical similarity simulation experiment model based on the similarity ratio; The physical similarity simulation experiment model is provided with a ventilation module, a mining loading and air source injection module, a ventilation-loading cooperative control module, a temperature regulation module, a fracture image acquisition module and a monitoring module; s5, simulating the mine environment in a physical similar simulation experiment model, and carrying out a coal seam exploitation experiment, wherein in the experiment process, a monitoring module is utilized to record the evolution process of a overburden fracture during coal seam exploitation, and the concentration and the flow rate of gas in real time; S6, analyzing parameter information of the overburden fracture based on the evolution process of the overburden fracture, and calculating diversion capacity and diversion weight coefficient of the overburden fracture based on the parameter information; S7, inputting the calculated diversion capacity, diversion weight coefficient and screened isotope index of each coal seam overlying strata fracture into a multi-end member mixing equation to obtain a mixed isotope value Judging And the measured isotope values If the deviation is less than or equal to 10%, the step S8 is carried out, otherwise, the step S6) is returned, and the diversion weight coefficient is modified; S8, reversely deducing all possible sources of the return corner gas based on the experimental data obtained in the step S5) and the multi-isotope combination source-dividing calculation method in the steps S6) to S7); S9, inputting the source, the migration path, the flow speed and the concentration of the return air corner gas obtained by deduction in the step S8) into a numerical model, simulating to obtain the real-time flow speed and the gas source concentration of the return air corner gas, judging whether the deviation between a simulation result and field data is less than or equal to 5%, if so, predicting the gas flow by using the numerical model, otherwise, adjusting key parameters of the numerical model, and reconstructing the numerical model.
2. The fully-mechanized coal mining face return air corner gas multi-source tracing method of claim 1, wherein in step S3), establishing an end member gas characteristic database comprises the following steps: S3.1, acquiring coal samples at the upper, middle and lower three positions of each coal seam by using a coring bit, respectively placing the coal samples into different aluminum foil sampling bags, and vacuumizing; S3.2, collecting gas after the coal sample releases the gas, measuring the stable isotope value of the gas by using a gas chromatograph-isotope mass spectrometer, and establishing an end member gas characteristic database.
3. The multi-source tracing method for return air corner gas of fully-mechanized mining face according to claim 1, wherein in step S5), a physical simulation experiment model is adjusted by using a ventilation module, a mining loading and air source injection module, a ventilation-loading cooperative control module and a temperature adjustment module to simulate an actual mine state; the ventilation module is used for setting ventilation boundary conditions in a physical similarity simulation experiment model so as to simulate the actual ventilation network of a mine and the gas source boundary of each coal seam goaf and provide stable ventilation conditions for gas migration in the experiment; the mining loading and air source injection module comprises a loading pressure head, a jack or an oil cylinder and a gas channel communicated with the coal seam and the goaf, and is used for applying the stress of the overburden layer and the pushing load of the working face to the physical similarity simulation experiment model and injecting air into the preset coal seam or the goaf through the gas channel so as to synchronously simulate the mining process and the multi-source air release process; The ventilation-loading cooperative control module is used for uniformly controlling the mining loading and ventilation boundary simulation process, so that the cooperative simulation of mining and ventilation conditions is realized. The temperature regulation module comprises a heating/refrigerating unit and a temperature sensor and is used for regulating and monitoring the temperature of the surrounding environment of the physical similarity simulation experiment model, so that the internal temperature field of the experiment model is matched with the actual working temperature under different underground buried depth conditions; The fracture image acquisition module comprises an industrial camera, a light source and an image acquisition and processing system, and is used for continuously shooting and recording the development condition of the model fracture in the coal seam exploitation experiment process, extracting the opening degree, the form, the trend and the penetrability of the fracture through an image processing technology, and providing basic data for the subsequent calculation of the fracture diversion capacity and the connectivity index of the overburden rock; The monitoring module comprises a stress sensor, a wind pressure sensor and a wind speed sensor and is used for monitoring stress and ventilation parameters at different positions of the physical similarity simulation experiment model and obtaining time-varying information of stress state, deformation characteristics and ventilation conditions of the overburden in the mining process.
4. The method for multi-source tracing of return air corner gas of fully-mechanized coal mining face as claimed in claim 1, wherein in step S6), the parameter information of the overburden rock fracture comprises the opening degree of the fracture Morphology and connectivity; Calculating the diversion capacity and the diversion weight coefficient of the overburden fracture based on the parameter information of the overburden fracture, wherein the diversion capacity of the overburden fracture The calculation formula of (2) is as follows: (1) Wherein: Is the gas viscosity; Is connectivity index, i.e. total length of the connected fracture/area of the monitored area; The calculation basis of the fracture diversion weight coefficient is that the fracture diversion weight coefficient is confirmed according to the diversion capacity ratio of the fracture area corresponding to each coal seam.
5. The multi-source tracing method for air return corner gas of fully-mechanized mining face according to claim 1, wherein in the step S6), the combined screening method is characterized in that the dimension reduction is carried out on isotope values of coal layer gas in an end member gas characteristic database based on principal component analysis, and then two groups of isotope indexes with the largest differentiation degree are screened out.
6. The fully-mechanized mining face return air corner gas multi-source tracing method is characterized in that in the step S7), a multi-end member mixing equation is established based on the principle of mass conservation, and the multi-end member mixing equation is as follows: (2) Wherein: the total layer number of the coal layer; Is the first Coal seam No Isotope values; =1,2; Is the first The flow conductivity of the coal seam fracture area accounts for a certain proportion; Is the first Fracture diversion weight coefficient of the coal seam.
7. The method for multi-source tracing of return air corner gas of fully mechanized coal mining face according to claim 1, wherein in step S7), the measured isotope values are as follows The measuring method comprises the steps of arranging a beam tube sampling system in an underground return airway, extracting mixed gas through the beam tube sampling system and measuring isotope values 。
8. The method for multi-source tracing of air at return corners of fully-mechanized coal mining face according to claim 1, wherein in step S9), the method for constructing the numerical model comprises the following steps: S9.1, establishing a three-dimensional model based on coal seam distribution, overburden fracture parameter information, simulation data of a physical similarity simulation experiment model and field actual measurement data; s9.2, dividing the model into a plurality of computing units, and setting an air source boundary and a ventilation boundary; s9.3, constructing a mathematical model of gas flow and diffusion based on Darcy' S law; S9.4, acquiring a plurality of groups of return air corner gas sources, migration paths, flow rates and concentration data as a data set; and S9.5, the data set is brought into a mathematical model of gas flow and diffusion to obtain a real-time gas flow rate and a gas source concentration, whether the difference value between the real-time gas flow rate and the gas source concentration obtained by simulation of the model and the measured real-time gas flow rate and the gas source concentration meets a threshold value is judged, if so, the construction of the numerical model is completed, otherwise, the step S9.1 is returned to, and the information of the overburden fracture parameters is modified.
9. An early warning system for a fully mechanized mining face return air corner gas multi-source tracing method based on any one of claims 1-8 is characterized by comprising a data acquisition module, a simulation calculation module, a prediction analysis module and an early warning response module; The data acquisition module comprises a plurality of sensors arranged in a mine and is used for acquiring the concentration, temperature, wind speed and pressure of the gas in the mine in real time; The simulation calculation module brings data obtained from the physical similarity simulation experiment model into a numerical model to obtain obtained simulation data; The multi-coal-seam fully-mechanized coal mining face gas flow model is established based on the coalseam gas occurrence content and the data acquired by the data acquisition module and is used for displaying migration and enrichment conditions of gas under a mine in real time; the prediction analysis module predicts the gas concentration distribution condition of each source and the gas concentration distribution condition of the return air corner of the working face in the future and judges whether a hypoxia area of the return air corner appears or not by utilizing an LSTM prediction model according to the simulation data; The condition of the low oxygen area of the return air corner comprises that the content of source nitrogen and source carbon dioxide exceeds the standard, and the diversion capacity of the gas migration path is strong; The early warning response module carries out early warning based on the prediction result of the prediction analysis module; The method for establishing the LSTM prediction model comprises the following steps: 1) A plurality of sensors are distributed in the mine at intervals, the real-time gas concentration, temperature, wind speed and pressure under the mine are collected through the sensors, and the occurrence content of coal seam gas obtained through drilling pre-extraction is used as an initial data set; 2) Preprocessing an initial data set to construct a training set; 3) And training the LSTM model by using the training set to obtain the LSTM prediction model.
10. The early warning system for the multi-source tracing method for the return air corner gas of the fully-mechanized coal mining face according to claim 9, wherein the concentration of nitrogen and carbon dioxide at the source corresponds to the diversion capacity, and the correspondence between low-concentration gas-high diversion capacity and high-concentration gas-low diversion capacity exists; Based on the corresponding relation, the prediction result of the early warning response module comprises: When the nitrogen concentration is greater than or equal to 85 percent and the carbon dioxide concentration is greater than or equal to 0.5 percent, and the flow conductivity is not more than the standard value under the current concentration, judging that the gas concentration at the source exceeds the standard, and the flow conductivity is not exceeded the standard; when the nitrogen concentration is more than or equal to 85 percent and the carbon dioxide concentration is more than or equal to 0.5 percent, and the diversion capacity exceeds the standard value under the current concentration, judging that the gas at the source exceeds the standard and the diversion capacity exceeds the standard; when the nitrogen concentration is less than 85 percent and the carbon dioxide concentration is less than 0.5 percent, and the diversion capacity exceeds the standard value under the current concentration, judging that the gas at the source does not exceed the standard and the diversion capacity exceeds the standard; When the nitrogen concentration is less than 85 percent and the carbon dioxide concentration is less than 0.5 percent, and the flow conductivity is not more than the standard value under the current concentration, the gas at the source is judged not to exceed the standard, and the flow conductivity is judged not to exceed the standard.

Description

Mine return air corner hypoxia multi-source tracing method and early warning system Technical Field The invention relates to the field of coal mine safety, in particular to a mine return air corner hypoxia multi-source tracing method and an early warning system. Background In the coal mining process, the stress field and the displacement field of the overlying strata are changed under the influence of engineering disturbance, and the overlying strata collapse and generate a large number of cracks. The cracks generated in the process can change the conduction state between different coal seam working faces of the multi-coal seam mine, and the gas migration capacity is enhanced. Whereas in a low gas mine with a shallow burial depth,、、And the alike gas can be accumulated in the coal seam by the migration of other coal seam goaf through the overburden cracks due to the factors such as pressure difference of working faces of different coal seams in the coal seam exploitation process. As coal mining advances, the migration path, concentration distribution, and source of the gas change and become denatured. The air return corner of the working surface is affected by the gases, so that hypoxia phenomenon can occur. Currently, for such hypoxia problems, gas source identification is mainly performed by means of isotope tracing and physical detection methods. However, the existing methods still have significant limitations: firstly, the conventional isotope tracing is mostly based on a single gas index, and characteristic overlapping is easy to occur when the components of the multi-coal-bed gas are similar, so that the source is misjudged; secondly, most models assume that the isotope value of the end member gas is constant, and the influence of dynamic evolution of the mining fracture on a gas migration path cannot be considered, so that an estimated result deviates from reality; Thirdly, the existing monitoring system is concentrated on the local gas concentration alarm of the corner, lacks the capability of real-time tracking and advanced early warning of gas sources, and is difficult to prevent and control the hypoxia risk from the sources. Disclosure of Invention The invention aims to provide a fully mechanized mining face return air corner gas multi-source tracing method, which comprises the following steps: S1, through geological exploration, the geological structures of a shearable layer and adjacent coal strata are counted, relevant geological information is recorded, and parameters of each coal bed, physical and mechanical parameters of the coal strata and geometric shapes of the coal beds and the coal strata are measured; s2, constructing a mine, and measuring the gas content, ventilation condition, temperature, gas pressure and coal bed gas components in the mine; s3, measuring isotope values of the coal bed gases, and establishing an end member gas characteristic database; S4, determining a similarity ratio of a physical similarity simulation experiment based on the coal bed parameters and the coal stratum physical mechanical parameters, and building a physical similarity simulation experiment model based on the similarity ratio; The physical similarity simulation experiment model is provided with a ventilation module, a mining loading and air source injection module, a ventilation-loading cooperative control module, a temperature regulation module, a fracture image acquisition module and a monitoring module; s5, simulating the mine environment in a physical similar simulation experiment model, and carrying out a coal seam exploitation experiment, wherein in the experiment process, a monitoring module is utilized to record the evolution process of a overburden fracture during coal seam exploitation, and the concentration and the flow rate of gas in real time; S6, analyzing parameter information of the overburden fracture based on the evolution process of the overburden fracture, and calculating diversion capacity and diversion weight coefficient of the overburden fracture based on the parameter information; S7, inputting the calculated diversion capacity, diversion weight coefficient and screened isotope index of each coal seam overlying strata fracture into a multi-end member mixing equation to obtain a mixed isotope value JudgingAnd the measured isotope valuesIf the deviation is less than or equal to 10%, the step S8 is carried out, otherwise, the step S6) is returned, and the diversion weight coefficient is modified; S8, reversely deducing all possible sources of the return corner gas based on the experimental data obtained in the step S5) and the multi-isotope combination source-dividing calculation method in the steps S6) to S7); S9, inputting the source, the migration path, the flow speed and the concentration of the return air corner gas obtained by deduction in the step S8) into a numerical model, simulating to obtain the real-time flow speed and the gas source concentration of the return air cor