Energy Evolution Mechanism and Damage Constitutive Model of Thermally Damaged Granite
Uniaxial compression tests of granite treated at 25℃,200℃,400℃,600℃ and 800℃were carried out to study the effect of temperature change on the mechanical properties,energy evolution and conversion mechanism of granite.Based on damage mechanics and Weibull statistical distribution theory,a piecewise constitutive model of granite treated at dif-ferent temperatures is established.The results show that when the temperature increases from 25 ℃ to 800℃,the peak stress and elastic modulus of granite gradually decrease,the peak strain gradually increases,and the granite gradually changes from brittle to ductile.The energy evolution curves of granite after high temperature are similar.The elastic energy before peak in-creases gradually,the dissipated energy increases first and then decreases,and the elastic energy after peak decreases sharply,the dissipated energy increases suddenly.The total energy and elastic energy of granite at the peak stress increase first and then decrease with the increase of temperature,the dissipated energy increases with the increase of temperature.The change of elas-tic energy consumption ratio reflects the transformation of thermal damage granite deformation stage.With the increase of tem-perature,the proportion of thermal damage granite compaction stage increases,the proportion of elastic and plastic deformation stage decreases,and the proportion of post peak stage increases.The compression stage of the thermal damage granite stress-strain curve is identified by the elastic energy consumption ratio,and a piecewise constitutive model of the thermal damage granite considering the compaction stage is established based on damage mechanics and Weibull statistical distribution theory.The theoretical value of the model is in good agreement with the experimental value,which can accurately describe the deforma-tion and failure process of the thermal damage granite.
thermal damagemechanical propertiesenergy evolutionelastic energy consumption ratioconstitutive model
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