Study on the correlation between physical and mechanical parameters of three types of rocks and resistance after high temperature
During the TBM digging process,the TBM cutter plate will produce different degrees of friction heat from the violent friction with the rock,which will increase the temperature of the TBM cutter plate.[Objective]In order to study the correlation between rock physical mechanical parameters and wear resistance after high temperature treatment,we propose a prediction model of rock physical mechanical parameters and CAI,and utilize rock physical mechanical parameter indexes to predict rock wear re-sistance,while exploring the change rule of rock CAI with temperature.[Methods]In this paper,taking granite,sandstone and marble as examples,we carry out cerchar abrasion test and rock physics and mechanics test on the rocks after different tempera-tures,and obtain the CAI,density,Leeb hardness,wave velocity,porosity,thermal conductivity and other physical parameters of the three kinds of rocks,and obtain the tensile strength,uniaxial compressive strength and other mechanical parameters.Finally,the prediction model of rock physico-mechanical parameters and CAI values is proposed based on linear regression meth-od.[Results]The result show that:(1)Regarding the physical properties of the rocks after high-temperature treatment,the cor-relation between the Leeb hardness,longitudinal wave velocity and CAI is good,and the correlation coefficients of R2 between the Leeb hardness and the CAI of granite,sandstone and marble are 0.944,0.714 and 0.885 respectively,and the correlation coef-ficients of R2 of the longitudinal wave velocity of three kinds of rocks are 0.925,0.835 and 0.891 respectively.The correlation between rock porosity and CAI is very low,with correlation coefficients R2 of only 0.171 and 0.657 for granite and sandstone,respectively.(2)With regard to the mechanical properties of rocks after high-temperature treatment,the tensile strength and uniaxial compressive strength of rocks correlate well with the CAI,and the correlation coefficients R2 of the tensile strength of granite,sandstone and marble with the CAI,are 0.874,0.888 and 0.950,respectively,and the correlation coefficients R2 of the uniaxial compressive strength of rocks can be as high as 0.962,0.996 and 0.877.[Conclusion]The result indicate that:(1)After high temperature action,the physical and mechanical properties of rock and wear resistance are reduced with the increase in temperature,and the decline in the magnitude of the rock type there is a big difference,the reason is that there is a significant difference in the coefficient of thermal conductivity,which affects the change rule of the physical and mechanical properties of the rock and wear resistance under the action of high temperatures.(2)In the evaluation of the correlation between rock physical and mechanical parameters and CAI after high temperature,the correlation model between rock mechanical index and CAI is obviously better than the correlation model between physical index and CAI.In the correlation model between physical indexes and CAI,the longitudinal wave velocity is the best,while the porosity is worse;in the model of mechanical indexes,the compressive strength is slightly better than the tensile strength.
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