Publication Date:
2018-06-25
Description:
Thermal damage, which is a typical damage form in the fields of geothermal energy extraction and nuclear waste disposal, seriously affects the transport characteristic and stability of candidate rocks. This study experimentally investigates the influence of initial thermal cracking on the mechanical properties of a coarse-grained marble. Uniaxial compression tests with acoustic emission (AE) monitoring were conducted on marble specimens after exposure to different temperatures. The physical and mechanical properties include porosity, P-wave velocity, rock strength, Young's modulus and Poisson's ratio, as well as the AE characteristics are then examined and discussed. It is found from thin section observation that the number of microcracks inside the specimen gradually increases with the increase in the treatment temperature, which is in good agreement with the results of the P-wave velocity and the effective porosity. The uniaxial compressive strength (UCS) and Young's modulus are found to decrease as the temperature in the treatment increases, while the Poisson's ratio gradually increases. Overall, the thermal treatment decreases the brittleness and increases the ductility of the rock specimen. In addition, the accumulated AE data correspond well with the recorded stress–strain curve and the failure planes determined from source location using AE are comparable with those observed in laboratory testing. Finally, a constitutive model based on AE data is established to capture the stress–strain relations after treatment with different temperature. The results show that the stress–strain curves interpreted from the proposed constitutive model agree well with those recorded in laboratory tests.
Print ISSN:
0956-540X
Electronic ISSN:
1365-246X
Topics:
Geosciences
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