| Rockburst is a common dynamic instability disaster in underground engineering excavation under high geostress environment.It has become one of the most difficult problems in the world's underground engineering,which is characterized by the sudden violent ejection of the surrounding rock or the throwing into the excavation space,threatening the safety of the construction personnel and equipment.Because the mechanism of rockburst is complex and has many influence factors,the prediction and early warning technology of rockburst can not completely meet the requirements of engineering practice.Therefore,the influence factors of rockburst and the corresponding experimental research on physical effects are carried out to obtain the characteristics,laws and mechanisms of acoustic emission infrared radiation under different conditions,which lays the foundation for the early warning and prevention of rockburst.This paper takes rock burst in underground mine tunnel as engineering background and research topics and carries out a detailed and systematic simulation of rockburst in roadway under different side pressure,different loading rate and water content condition.It takes the indoor simulation experiment as the main research means and uses acoustic emission and infrared technology as the monitoring means.The characteristics and mechanism of rockburst failure under three influencing factors are discussed,and the mechanism of acoustic emission and infrared radiation in the process of rockburst is deeply studied.On the basis of this,acoustic emission infrared monitoring technology for rock burst disaster is put forward to provide theoretical and experimental basis for prediction and early warning of rockburst in underground works.It is of great significance to understand the mechanism of rock burst and predict rockburst.To sum up,the research contents and main achievements of this paper are as follows:(1)Influence of lateral pressure on macroscopic failure,acoustic emission and infrared characteristics of tunnel rockburstThree different lateral pressure(4.44MPa?8.88MPa?13.32MPa)rock burst simulation experiments were carried out.The characteristics of macroscopic failure,acoustic emission characteristics and infrared radiation characteristics of three kinds of rock burst under lateral pressure were compared and studied.The results of the study show that:? There are four stages in the process of rock burst in tunnel,namely,"quiet period particle ejection,sheet stripping and severe rock burst".When the lateral pressure increases,the stress increases is ejected,the stage of particle ejection and flake peeling becomes shorter,the process of rock burst is accelerated,and the total mass of rock burst is increased.The rockburst pit is characterized by deep "V" type,with sudden and destructive rock burst.? When the lateral pressure increases,the intensity of the low frequency and high amplitude signal emission increases rapidly,while the high frequency and low amplitude signal speed decreases.This indicates that the precursory characteristics of acoustic emission parameters of rock burst are more obvious when lateral pressure increases.? The lateral pressure affects the infrared radiation effect in the process of rock burst.First,the lateral pressure increases,the difference between the rock burst zone and the non rock burst zone increases.The difference between the two temperatures is obvious,which is more conducive to identify the dangerous area of rock burst.The second is that the lateral pressure increases,the shear failure of the rock burst is enhanced and the friction between the debris increases,which leads to the increase in the proportion of the heated debris in the stage of violent rock burst and the increase of the temperature.(2)Influence of loading rate on macroscopic failure,acoustic emission and infrared characteristics of tunnel rockburstThree kinds of loading rates(0.3mm/min,0.4mm/min and 0.5mm/min)were used to simulate rock burst in granite tunnel.The influence of loading rate on rock burst process is discussed from three aspects of rock burst characteristics,acoustic emission characteristics and infrared radiation characteristics.The results of the study show that:? When loading rate increases,the stress of particle burst occurs when rock burst occurs,and the time of rock burst process is shorter.Rockburst develops rapidly and shocks increase,that is,the early and rapid development of rock burst,which increases the difficulty of rock burst monitoring.?With the increase of loading rate,the acoustic emission activity of rock burst tends to be strong,and the energy adjustment is intensified.The intensity of low frequency and high amplitude signal shows sudden increase in rock burst stage and can be used as an important precursor information for rock burst.?The influence of loading rate on the infrared radiation characteristics of rock burst process is mainly manifested in two aspects:Firstly,with the increase of loading rate,the mechanical properties of rock samples in the whole rock burst process decrease,and the temperature rise in rock burst area decreases.Secondly,when the loading rate increases,the tensile failure of the rock burst is enhanced and the degree of friction between the debris decreases,which leads to the decrease in the proportion of the heated debris in the stage of violent rock burst and the decrease of the temperature.(3)Influence of water on macroscopic failure,acoustic emission and infrared characteristics of tunnel rockburstThe simulation experiment of rock burst under natural and saturated conditions was carried out,and the effects of water on the macroscopic failure,acoustic emission and infrared radiation of rock burst were obtained.? Compared with natural conditions,rock burst under water saturation presents the characteristics of increasing damage scope and decreasing dynamic damage.?Compared with natural conditions,the acoustic emission rate of rock burst increased significantly under saturated condition,but the energy of acoustic emission decreased significantly.Under the condition of saturated water,the characteristics of the high frequency and low amplitude signal denseness of the rock burst are different from that under the natural conditions.The characteristics of the initial increase and then decrease in the stage of pellet ejection can be used as the important precursor information for the burst of rock burst under the condition of full water.?On the one hand,the temperature increase in the rockburst process of saturated granite is larger than that of natural rocks.On the other hand,when the rock outburst,the cooling effect of ejection and shedding blocks is stronger than that of natural rocks,and water plays a role in cooling down rockburst and debris.The above two effects indicate that the infrared radiation monitoring effect for rock burst in saturated rock will be better.(4)A joint monitoring technology model for rock burst acoustic emission infrared radiation is established from the time and space dimension of rock burstUsing the research idea of "experimental law mechanism analysis and application practice",based on the sound emission and infrared laws obtained from rock burst experiment,a new idea of acoustic emission infrared monitoring based on space-time strong structure of rock burst is proposed.The monitoring index of time,space and intensity of rock burst and its precursory manifestation are expounded.On this basis,a combined acoustic emission and infrared monitoring model of tunnel rock burst emission and infrared is established,and the feasibility of its practical application is discussed.The experimental results further reveal the influence mechanism of different factors on the rock burst process,and provide an experimental basis for the application of acoustic emission and infrared application to the monitoring and early warning of rock burst disasters in the roadway. |
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