Thermal Contact Resistance of Granite Joints Under Normal Stress

• Published in: Rock mechanics and rock engineering 2023-11, Vol.56 (11), p.8317-8338
• Main Authors: Li, Zheng-Wei, Long, Meng-Cheng, Xu, Peng, Huang, Chuan-Yuan, Wang, Yun-Sen
• Format: Article
• Language: English
• Subjects: Apertures; Civil Engineering; Contact resistance; Contact stresses; Deformation; Discontinuity; Earth and Environmental Science; Earth Sciences; Equivalence; Evolution; Geophysics/Geodesy; Granite; Heat transfer; Jointed rock; Mathematical models; Normal stress; Original Paper; Plastic deformation; Rock; Rock masses; Rocks; Roughness; Roughness coefficient; Thermal contact resistance; Thermal resistance
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-023-03450-9

Heat transfer in jointed rock masses exhibits characteristics of discontinuous, heterogeneous, and anisotropic due to the effects of rock discontinuities. In this work, thermal contact resistance (TCR) evolution of granite joints under normal stress was investigated. A novel method was proposed for the measurement of TCR for rough rock joints. A numerical calculation program was established for the determination of contact area based on the initial morphology of the joint surfaces and the monitored joint closure during the experiment. An estimation model of TCR for granite joints based on the equivalent joint aperture was established. It is found that TCR of granite joints shows decreasing trend with normal stress. The decreasing rate is relatively large at the initial loading stage and gradually reduces with normal stress. The values of TCR eventually stabilize. TCR of granite joint has no obvious correlation with joint roughness coefficient. It is more significantly affected by the contact area. Plastic deformation and rupture of the micro-convex body on the joint surfaces occurred due to the application of normal stress, which improve the heat transfer efficiency and lead to the decrease in TCR. In general, predication results of the TCR estimation model show good consistency with the experimental data. The model is more suitable for the cases with small joint apertures. This study can provide knowledge to the better understanding of heat transfer in rock masses containing different kinds of discontinuities. Highlights A novel method was proposed for the measurement of thermal contact resistance for rough rock joints. A numerical calculation program was established for the determination of contact area for rough rock joints. Evolution of thermal contact resistance with normal stress and joint contact area was obtained and analyzed. An estimation model of thermal contact resistance for granite joints based on the equivalent joint aperture was established.