Experimental Study On Spraying Insulation Mechanism Of High Ground Temperature Roadway

On the basis of the research on the heat insulation method of"composite heat-resisting ring",and noting the foundation and importance of the research on the spray-injection insulation,this paper focuses on the thermal insulation mechanism of spray-spraying layer.In this paper,theoretical analysis,experimental research,similarity simulation and numerical simulation are used to study the thermal insulation mechanism of grouting in high temperature roadway.Based on the theory,the heat transfer mode and the heat insulation mechanism of the grouting heat insulation roadway are analyzed.Through experiments,thermal insulation materials suitable for high ground temperature roadways are developed.With the help of"Similar Simulated Test System of High Ground Temperature Roadway",the characteristics of radial temperature field and feasibility of grouting insulation of surrounding rock of high ground temperature roadway are studied.At the same time,the effects of ventilation parameters and original rock temperature on insulation effect are explored.In this paper,numerical simulation method is used to analyze the temperature distribution of surrounding rock and the feasibility of grouting insulation in high ground temperature roadway,and the effect of grouting layer parameters on cooling effect is discussed.With the help of discussion from different angles and verification by similar simulation,the paper further enriches the theory of"composite thermal ring".The main results are as follows.?1?Based on the analysis of heat transfer theory of surrounding rock of thermal insulation roadway,a mathematical model of unsteady heat conduction of surrounding rock of high geothermal roadway with thermal insulation ring structure is established according to the structural characteristics of thermal insulation ring.Through the theoretical analysis of the temperature field of the surrounding rock of the thermal insulation roadway,the temperature distribution formula from the wall of the thermal insulation roadway to the original rock is obtained.In this paper,the influencing factors of equivalent thermal conductivity of grouting layer are analyzed in detail,such as porosity,fracture characteristics,fracture medium,medium characteristics,etc.Finally,the cooling effect is predicted,and the formula for calculating the heat release and emission reduction from the surrounding rock of the grouting roadway to the wind flow is?Q=K_?UL?t₀-t_f?-K_?'UL?t₀-t_f?.?2?Taking ordinary Portland cement,fly ash,sand and vitrified microspheres as raw materials,through orthogonal test,optimizing the proportion of thermal insulation materials for mining,the influence of various factors on the performance of the material was analyzed,and a kind of lightweight thermal insulation material with good thermal insulation and strong bearing capacity was developed to meet the needs of thermal insulation and cooling for mining.?3?Based on the similarity theory and the similarity criterion of surrounding rock temperature field of high temperature roadway,the similarity criterion of surrounding rock temperature field of grouting insulation roadway is analyzed.With the help of similar simulation test system,the similar test of high geothermal grouting heat insulation roadway was carried out.The radial temperature distribution characteristics of surrounding rock before and after grouting in high geothermal roadway were explored,the thermal insulation effect of surrounding rock grouting in roadway was analyzed,and the effects of ventilation parameters and original rock temperature on cooling effect were studied.Finally,it is concluded that the dimensionless temperature of surrounding rock decreases with the increase of wind speed,and the influence of wind temperature and original rock temperature on the temperature field of surrounding rock of grouting insulation roadway is not obvious.?4?By using COMSOL numerical simulation software,the thermal insulation of grouting in high-temperature roadway is simulated,and the characteristics of radial temperature field before and after grouting in high-temperature roadway are analyzed.In this paper,the rationality of the similar test results is verified from different angles,and the effect of the characteristics of the spray layer on the cooling effect is further discussed.Finally,the conclusion is that the bigger the thickness of the grouting layer is,the more obvious the obstruction effect is;the lower the thermal conductivity of the insulation material is,the better the thermal insulation effect is.