1 Jul 2017
1 Dec 2017 (Extended to 10 Jan 2018)
15 Jan 2018
16 Apr 2018 (Extended to 15 Jun 2018)
From 16 July 2018
By 17 September 2018
Young Researcher Plenary
Tsinghua University, China
Thu-01 Nov 2018 | 09:15 – 09:35 | Summit 2
"Thermally-induced Microcracking in Granites: Insights from SEM Observation and DEM Modeling"
A large number of laboratory experiments about the influence of heating or heating-cooling cycles on the mechanical properties of various granites are reviewed. Both scanning electron microscopy (SEM) and particle-based discrete element modeling (DEM) are employed to quantitatively elucidate the mechanisms responsible for temperature-dependent mechanical properties of granites, from a perspective of microcracking. Both SEM observations and DEM simulations give consistent results and show that there exists a temperature threshold beyond which the thermally-induced microcracks increase drastically. Both intergranular and intragranular microcracks are observed in the granites after thermal treatment, and intergranular ones are dominant. A continuous increase in temperature can generally weaken granites, mainly by inducing significant thermal stress and generating tensile microcracks. The weakening of granites after a heating-cooling cycle is due only to the thermally induced microcracks. With increasing grain size the magnitude of Brazilian tensile strength reduction of granites due to thermal treatments becomes small, whereas with increasing heterogeneity in grain size distribution, the magnitude of Brazilian tensile strength reduction of granites due to thermal treatments becomes great. This is because the two competing mechanisms, i.e., the length and number of the thermally induced microcracks in granites.
Zhihong Zhao is currently an associate professor in the Department of Civil Engineering at Tsinghua University, China. He obtained PhD on rock mechanics at Royal Institute Technology (KTH), Sweden, in 2011. He serves as an editorial board member for Computers and Geotechnics. His main research interest is coupled thermal-hydrological-mechanical- chemical (THMC) processes in fractured rocks, with principal applications in deep underground engineering such as Enhanced Geothermal Systems, underground nuclear waste repositories, and underground storage for energy. He has published about 40 peer-reviewed journal articles and 1 book chapter. The publications have been cited by about 500 times according to Google Scholar.