| Through the research of the related literature of mine thermal pollution and analysis of the related research status of the temperature field and the heat dissipation of roadway surrounding rock. According to the data of investigation analyze and confirm the principal factor of heat dissipation of roadway surrounding rock. The role of all the factors between surrounding rock and air flow have been known in detail, and the heat conduction differential and integral equations have been deducted according the influence factor in theory. Meanwhile, The single-valued condition of the phenomenon that the heat transfer between the roadway surrounding rock and flow under the periodic boundary have been analyzed. Then introduce the dimensionless criterion to dimensionless analysis the thermal conductivity control equation of surrounding rock temperature field. For ease of the analysis with numerical methods, the separation of variables should be used in both the control equation of thermal conductivity and the single-valued condition. The two-dimensional roadway in the cartesian coordinates and one-dimensional roadway under cylindrical coordinate system of the surrounding rock thermal numerical theory method under the periodic boundary and the non-periodic boundary conditions have been established by the finite volume method. For the analysis of the optimal equivalent circular roadway equivalent radius accessor methods, the numerical method has been used to calculate the heat dissipation of noncircular roadway surrounding rock. the relation theory to implement on the finite volume method. The three noncircular roadway about trapezoidal, arch and rectangle respectively contrastive analysis of the commonly three equivalent method such as perimeter, area and hydraulic diameter. The optimal calculation method of the equivalent circular roadways is determined by comparing error and theoretical analysis. Then calculate the heat dissipation of surrounding rock with the annual average temperature by check the map. And, under the periodic boundary conditions, when analysis the temperature field variation law of roadway surrounding rock. In the practical engineering application, the theoretical calculation formula is so complex that not convenient to use, thus the relatively simplified thermal conductivity control equations of surrounding rock in the periodic boundary conditions are built to adapt to the engineering application. according to the law of conservation of energy, further study can be done to analyze the change of wind temperature volatility amplitude and phase angle, along the direction of roadway in the periodic inlet wind temperature conditions. In order to confirm the correctness of the calculation formula, the similar simulation experiment platform of roadway surrounding rock has been build in the laboratory to analysis the change law of the similar surrounding rock body inner temperature under the different inlet wind conditions, and the experimental results and theoretical analysis results were compared. Finally based on the above theoretical analysis and numerical calculation, the heat dissipation of the noncircular and circular roadway surrounding rock simulation software has been developed with C++ language and Qt framework for graphical applications, and through a example demonstrates how to use the software to calculate.Through the above study, following conclusions can be drawn:(1)Analysis of the numerical computation method of surrounding rock heat dissipation and influence factors between surrounding rock and flow This section summarize main influence factors of surrounding rock heat dissipation, which involving roadway surrounding rock and roadway airflow. It is key that introduce the fundamental physical quantity of thermophysical parameter of surrounding rock body and airflow and also explain those computing method, the use of measuring instruments, value range and so on. The roadway cross-section shape, roughness of surrounding rock and original rock temperature for the heat transfer effect between surrounding rock and airflow have also been analyzed. On this basis, the basic rules of heat dissipation of roadway surrounding rock has been the theoretical analysis. the heat conduction differential equation and integral equation under the rectangular and cylindrical coordinates has been build. Meanwhile single valued conditions of roadway surrounding rock have also been analyzed, they are respectively geometrical conditions, physical condition, time conditions, and boundary conditions. Then introduce dimensionless number and the dimensionless of the heat conduction governing equation of surrounding rock and periodic boundary. Finally the heat conduction governing equation with separation of variables has been decomposed to stripping the annual average temperature from airflow temperature so that the heat conduction governing equation under the annual average and airflow temperature fluctuations with the dimension and dimensionless have been obtained. The above theoretical analysis for the following numerical calculating method make a good bedding. On the basis of the above, the merit and demerit of three kinds of commonly numerical computation method of surrounding rock heat dissipation, they are respectively finite difference method, finite element method and finite volume method. The finite volume method comparing the other have clear physical meaning and relatively high calculation accuracy in solving heat conduction problem. Therefore, this paper take the finite volume method as basis method to carry out the research work. To the basis principle of the finite volume method analysis the two-dimensional unsteady heat conduction integral equation and one dimension heat conduction differential equation under cylindrical coordinate system under periodic boundary condition. The heat balance equation derivational process of internal nodes and boundary nodes respectively have been build. Finally through the numerical calculation of an example, and getting the temperature field of surrounding rock of roadway and the relation between scope of cooling ring and ventilation time, and the change regulations of different depth of surrounding rock temperature over time and the calculation of the heat dissipating capacity of surrounding rock were analyzed. This calculation has certain guiding significance for the analysis of trapezoid roadway heat dissipation.(2) Computational simulation software on the heat dissipation of surrounding rock Based on the platform of C++ language, with Qt framework for graphical applications, the software calculating on the heat dissipation capacity of surrounding rock of roadway in periodic and a periodic boundary conditions is developed. The simulation software briefly introduces about three shapes of roadway and two kinds of boundary conditions, in the window, there are the input of basic parameters, the building of physical model, meshing, and time division. The programming is roughly divided into four parts: the login module, the selection module of calculating roadway shape, the calculating module of temperature field of surrounding rock, and the results showed module. There are corresponding introduction to program design and function of each module. Finally, combined with user interface, the using process of software is introduced in detail so as to help users have a simpler and more convenient experience. Certainly, the software interface and internal corresponding code have been analyzed and optimized in order to convenient researchers to do related study in the future.(3) Obtain the optimal equivalent circular equivalent radius to calculate the heat dissipation of surrounding rockThis section get the computation method of the equivalent radius that the head dissipation of noncircular roadway convert to the head dissipation of circular roadway and discuss its the important significances. The computing method both the heat dissipation of surrounding rock wall and the heat transfer resistance of surrounding rock is summary. According to the essence of calculating equivalent radius. three kinds of equivalent circular roadway method contrastive analysis that the commonalities and differences of calculating noncircular roadway and the equal perimeter method is the best method in calculating equivalent circular roadway surrounding rock heat dissipation. the three shapes of circular roadway is selected to error analysis respectively three equivalent circular roadway methods. The result shows that the relative error of equal perimeter method much less than the other two methods. This illustrates the equal perimeter method are more accuracy than the other. The result standard the selective methods for the equivalent circular radius of surrounding rock, which provides a theoretical basis for the practical engineering application.(4) Impact analysis of unsteady periodic airflow temperature on temperature field of surrounding rock mineAfter completing the computation method of the equivalent circular roadway, the further discussion that heat dissipation characteristics of temperature field under periodic boundary. The theoretical analysis the airflow temperature change under the surface air temperature periodical change with the wind site in mine. In this paper, the influence of the annual average temperature on the heat dissipation of surrounding rock has been stripping and the key to discuss the influence of the cyclical fluctuation air temperature on the heat dissipation of surrounding rock. On the base of the numerical calculating theory compile the procedure to solve the governing equation. Respectively the change regulation of surrounding rock wall temperature, surrounding rock internal temperature, and heat dissipation of surrounding rock under the periodic airflow temperature. In order to get the unified calculation formula and using the dimensionless analysis method. finally the calculation formula of semi-infinite object in the periodic boundary condition is taken into account so as to deduce the simplified calculation formula. According to the periodic wind temperature’s effect on the temperature field of surrounding rock of roadway, meanwhile combined with the principle of conservation of energy, the research analysis is about the periodic inlet wind flow’s effect on the wind temperature along the roadway, namely when the mine inlet wind temperature is in periodic change, we pay attention to the wind temperature changing law of wave amplitude and cycle phase angle at different sites along the axial direction. This study has a certain guiding significance for the engineering and technical personnel to predict the wind temperature.(5) Manufacture the similitude simulation experiment of temperature field of surrounding rockThe above section have completed the theoretical analysis, based on the temperature field similarity criterion of surrounding rock of roadway and physical similar experiment method, the simulation experiment system, similar with the environment of surrounding rock of roadway in the periodic wind temperature change conditions, is independently designed, and the similar experimental simulation platform is built using appropriate experimental materials, then the experimental results is taken to compare with the calculation results, in this way the unsteady periodic temperature change rule can be verified through the results. |
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