Abstract:A new electrical method of conductive carbon-film (with waterproof and anticorrosion ability) was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition. A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens (where the temperature is only changed) by this new electrical method of conductive carbon-film. Calculation results obtained by the energy method coincide well with the test results. And the higher the temperature is, the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are, which can prove the validity of the new electrical method. This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical, optical and acoustic methods, and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.

Key words: crack propagation rate; electrical method of conductive carbon-film; thermo-hydro-mechanical-chemical coupling; energy method; brittle rock