| In the process of coal mining,the surrounding rock of roadway is affected by mining speed,engineering space size and other factors.The load change of rock mass is an important factor to induce dynamic disaster of surrounding rock.The stress failure process of rock is accompanied by the release of heat energy,elastic wave energy,electromagnetic radiation energy and other energy.Using the energy release characteristics to study the failure and instability of loaded rock(body)can provide technical support for the early warning of mining rock mass failure.Therefore,this thesis carried out the observation experiments of rock infrared radiation under different loading rates,and carried out the basic theoretical research on the mechanical properties,infrared radiation characteristics and acoustic thermal correlation of rock loading failure.Based on the indoor experimental research,the transportation roadway of I010401 working face in Hongliu coal mine is selected to carry out the on-site infrared radiation observation test of mining rock mass,and the infrared radiation law of roadway surrounding rock and the early warning threshold of infrared radiation damage are studied.The main conclusions are as follows:(1)The failure mechanical properties and failure mode characteristics of rock under different loading rates are analyzed.With the increase of loading rate,the compressive strength of rock increases gradually,and the slope of elastic deformation stage increases gradually,and the influence is more obvious when the loading rate is low;Under different loading rates,the rock is mainly compression shear failure.The greater the loading rate is,the more broken the rock sample is.(2)The infrared radiation characteristics of rock failure under different loading rates are analyzed.The average infrared radiation temperature,the variance of variance of successive minus infrared radiation thermal image and infrared thermal image sequence diagram are used as infrared sensitivity indexes;Based on the denoising of the average infrared radiation temperature of the loaded rock sample by the reference rock sample,the change curve after denoising is roughly divided into three categories,and the influence of the change of loading rate on the average infrared radiation temperature is analyzed.(3)The variance of variance of successive minus infrared radiation thermal image and the evolution characteristics of thermal image sequence diagram under different loading rates are analyzed.The mutation of the variance of variance of successive minus infrared radiation thermal image is screened by using the Pauta criterion,and the relationship between the first two mutation times and loading rate is analyzed;Infrared thermal image sequence diagram includes original infrared radiation thermal image sequence diagram and successive minus infrared radiation thermal image sequence diagram.The evolution and differentiation characteristics of rock surface temperature field described by the two kinds of thermal images are compared.(4)The acoustic thermal correlation of rock failure and instability under different loading rates is analyzed.The response level of acoustic emission parameters(ring count,energy)in different stages of rock loading is related to stress and loading rate;The variance of acoustic emission parameters and variance of successive minus infrared radiation thermal image will have synchronous mutation in the process of rock failure,and the number of synchronous mutation is 1 ～ 5 times.(5)The infrared radiation law of in-situ mined rock mass is analyzed.Based on the deformation analysis of surrounding rock of transportation roadway in I010401 working face,the changes of infrared radiation temperature of roadway roof and non stope surface with the advance of working face are studied.The infrared radiation reference threshold calculated by the variance of successive minus infrared radiation thermal image is 0.00626.There are 50 figures,16 tables and 118 references in this thesis. |
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