Basic analysis of rock mechanical and thermal properties in South Korea

This study analyzed the mechanical and thermal properties of various rock types found in South Korea. The results showed that both igneous and metamorphic rocks possess higher strength compared to sedimentary rocks. The Young's modulus of rocks is dependent on the extent of weathering they have undergone. The average cohesion of granites was found to be relatively higher compared to other rock types, and their friction angle also exhibited a relatively high value with a considerable variance. The results of uniaxial compression strength testing with respect to depth revealed that rock strength generally increased with depth, however, there was a large variance in strength distribution in each depth interval. Based on these findings, it can be concluded that South Korea can also secure HLW disposal sites and facilities in terms of rock mechanics by using crystalline rocks, similar to countries such as Sweden and Finland where disposal facilities are being built.

Regarding the thermal properties of rocks, they are influenced by the distribution of the parent rock. The thermal conductivity is highly concentrated in the southwest and central regions of South Korea, while the geothermal gradient is high in the northeast, west, and some parts of the southeast regions. The southeast region of Korea has a high geothermal heat flow, and some central northern regions also exhibit relatively high geothermal heat flow. In light of these distributional characteristics, it is crucial to continue conducting precise studies on the mechanical and thermal properties of rocks in the future disposal depths of spent nuclear fuel.