(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，China；2. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering，Ministry of Education，
Wuhan University，Wuhan，Hubei 430072，China)
Abstract：In order to understand the progressive failure process of marble after thermal treatment at different temperatures，uniaxial compression tests were conducted on marble specimens after they were treated at temperatures of 25 ℃，200 ℃，400 ℃ and 600 ℃ respectively. Comprehensive studies were carried out on the characteristics of the detected acoustic emission(AE)，the failure mode of the specimens，the crack initiation stress and the damage stress level，the damage evolution and the stress-strain constitutive model. The results showed that as the treatment temperature increases，the peak strength of the rock decreases with increased corresponding peak strain，indicating that the rock becomes more ductile. It was also seen that the AE characteristics of the specimens treated at high temperatures show clear differences to those of the specimens treated at room temperature. Because of the thermal damage，the AE of the high temperature treated specimens was more active during the initial loading stage compared with specimens treated at room temperature. However，the AE in the elastic stage was less active compared with that of undamaged specimens. The ranges of the normalized crack initiation stresses and damage stresses determined using the AE method were 0.33–0.46 and 0.71–0.82 respectively，and both tend to increase as the treatment temperature increases. The failure mode changed from a single splitting crack to multiple splitting cracks，and finally to shear failure，which was in good agreement with the results derived based on AE locations. A variable describing the degree of damage was then established based on the accumulated AE count. For specimens treated at 25 ℃，the damage process can be divided into four stages，and for specimens treated at high temperatures，the initial damage level is high but the variation of the damage variable becomes gentle as the strain changes. Finally，a constitutive model based on the axial crack strain，the axial stress，and the damage variable determined from the AE count was established. Simulation results using the proposed constitutive model agreed well with the test results，and the higher the treatment temperature，the better the agreement.
杜守继，刘 华，陈浩华，等. 高温后花岗岩密度及波动特性的试验研究[J]. 上海交通大学学报，2004，37(12)：1 900-1 904.(DU Shouji，LIU Hua，CHEN Haohua，et al. Experimental research on the density and wave characteristics of granite rock after high- temperature[J]. Journal of Shanghai Jiaotong University，2004，37(12)：1 900-1 904.(in Chinese))
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2015, Vol. 34 
