Research On The Thermal Evolution Law Of Coal Rock Fracture Force Under The Conditions Of Deteriorating Factors

Nowadays,most coal and rock dynamic disaster accidents are caused by a variety of factors.However,the common result is that the internal deterioration of coal and rock changes its physical and mechanical properties,resulting in instability and destruction.Therefore,studying the mechanical properties of coal and rock under different deteriorating factors can provide data analysis and construction suggestions for underground mines,mine excavation and even roadway construction.This paper conducts uniaxial compression tests on coal and rock under the influence of three different degradation factors,uses load stress and infrared radiation to monitor the coal and rock load failure process in real time,and analyzes the load and average infrared radiation temperature under various conditions.The highest infrared radiation temperature data information.In view of the failure form of coal rock after its instability failure,the change characteristics of each data corresponding to time,the distribution characteristics of the infrared radiation temperature field on the coal rock surface,the comparison of load-time curves,etc.,the rules are found.After summarizing the characteristics of the infrared radiation temperature curve of coal and rock,the precursor phenomenon before its instability and failure is analyzed,and the concept of curve dispersion is introduced to change the coal and rock specimens from the old phase to Quantitative analysis of the change process of the new phase state,and deduced the calculation formula of curve dispersion.The test and analysis results show that:(1)The results of the infrared radiation temperature test show that the coal and rock have three distinct stages of radiation during the failure process under load,namely: the initial pore compaction stage,the fracture expansion stage under pressure,and the instability failure stage.(2)The prefabricated fissures have a great influence on the physical and mechanical properties of coal and rock,especially its failure form.The failure of coal and rock presents obvious localized characteristics and focuses on the middle part of the specimen,which indicates that the main failure type of coal and rock is the lateral expansion and tensile failure in the middle part,and the upper and lower ends are not effective due to the small strain.The prefabricated transverse cracks have a certain degree of restriction on the vertical cracks that penetrate up and down,hinder the expansion of the through cracks,and restrict the range of instability and damage in the central part of the coal.Compared with the prefabricated longitudinal cracks,the length and width of the through cracks are longer.It is small,and the fractured section area increases with the increase of the number of prefabricated fractures when failure occurs,but it is still smaller than the prefabricated longitudinal fractured coal and rock specimens under the same number of conditions.Approximately 20% of the time before the main fracture of coal and rock,the average infrared radiation temperature curve showed obvious signs of cooling,indicating that the perforating fractures changed from the expansion stage to the dislocation failure stage.(3)As the loading rate increases,the instability failure of coal and rock gradually changes from multi-section rupture to single-section rupture,and the characteristics of coal and rock surface fissures change from V-shaped to Y-shaped,and finally become a connection connecting the upper and lower ends.Rift.Infrared radiation temperature of coal rock shows that more heat accumulates in the middle,and as the loading rate increases,the temperature difference between the peak and the minimum value of the coal rock temperature curve also increases.The increase of loading rate hinders the advancement of the time point of the cooling precursor phenomenon of coal and rock instability failure.The greater the loading rate,the closer the time point of the cooling precursor to coal rock failure and failure stage,and the friction effect is more obvious.(4)The influence of immersion time on the average and maximum infrared radiation temperature curve dispersion of coal is smaller than other degrading factors.When the immersion time is longer,the curve dispersion of coal and rock at the initial stage of loading is higher,and coal and rock loss The dispersion of the highest infrared radiation temperature curve during stable failure is lower,and the rising amplitude of the infrared radiation curve when the main fracture occurs in coal rock shows an increasing trend as the water immersion time increases.