4.7 Article

Thermally Induced Microcracks in Granite and Their Effect on the Macroscale Mechanical Behavior

Journal

Publisher

AMER GEOPHYSICAL UNION
DOI: 10.1029/2022JB024920

Keywords

thermal effect; microcracking; granite; real-time experiment; grain-based modeling

Ask authors/readers for more resources

Understanding the thermal effects on rock is critical for geothermal resource exploration and understanding Earth's temperature-driven evolution. This study observed the thermal-induced microcrack propagation of granite in real time using an ultrahigh-temperature instrument on an optical microscope. The experimental results revealed that microcracks initiate at 300°C and coalesce between 400 and 600°C, which is the main reason for the sharp decrease in macroscale mechanical properties of granite.
Understanding the thermal effects on rock is critical for the exploration of geothermal resources and the temperature-driven evolution of Earth. The macroscale mechanical behavior of granite under thermal loading can be complicated due to microcracking and the heterogeneity of minerals. In this study, the thermally induced microcrack propagation of granite was first observed in real time by an ultrahigh-temperature instrument on an optical microscope. The previous investigation believed that the alpha-beta quartz transition at approximately 573? leads to a sharp decrease in macroscale mechanical behavior. However, the present experimental results revealed that microcracks initiate at 300? and coalesce between 400 and 600?, which is the main reason for the sharp decrease in macroscale mechanical properties of granite. Additionally, an accurate grain-based model based on the mineralogical morphology of granite samples adopted mechanical parameters of minerals obtained from microscale rock mechanical techniques. It is able to well reproduce the process of microcracking and the strength evolution of granite during heating. The numerical results show that the heterogeneity of thermal expansion and mechanical properties of minerals produce local thermal stress concentrations in granite. The uneven tensile-compressive stress between feldspar and quartz and the shear stress around biotite result in the initiation and propagation of microcracks. The present work is potentially useful for understanding and predicting the mechanical behavior of granites under thermal loading with different mineral compositions and microstructures.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available