## 6 Discussion  
Regression equations for mean values of rock properties in Figures 8-11, showing the changes of physical properties with increasing freeze-thaw cycle of rocks, were derived based on the experiment results. Table 4 summarizes correlation coefficient (R\({}^{2}\)) of the relationships between the freeze-thaw cycle and physical properties of UCS, shore hardness, absorption, and P-wave velocity of two rock types from Locations A and B, respectively. As presented in Table 4, UCS and shore hardness show weak correlations that the R\({}^{2}\) of the mean values of UCS and shore hardness were 0.0716-0.4073. Relatively higher R\({}^{2}\) values (0.9860-0.2836) were observed for absorption and P-wave velocity.  
Figure 11: P-wave velocity changes with increasing freezing-thaw cycle of Locations A and B.  
As mentioned previously in this paper, repetitive freeze-thaw actions of rocks induce increases of the number and the sizes of both surface/internal pores and internal micro cracks of rocks. These increases of pores and internal micro cracks of rocks increase rock absorption due to increased voids and void surface areas and decrease P-wave velocity due to delayed wave propagation due to increased voids/micro cracks/fissures within the rock specimens. On the other hand, ideally, UCS and shore hardness may decrease with increasing freeze-thaw cycle due to increases of pores and more developed micro cracks and fissures. However, clear trends of decreases of UCS and shore hardness were not identified because of the impossibility of using the identical sample specimens of rocks. Therefore, randomly distributed major directions of pores/micro cracks/fissures with respect to loading direction significantly influences UCS and shore hardness. Consequently, absorption and P-wave velocity exhibit much higher correction (much higher R\({}^{2}\) values) with freeze-thaw cycle compared with those of UCS and shore hardness. Use of absorption and P-wave velocity is proposed to evaluate degree of freeze-thaw weathering of rocks.  
From the analysis of freeze-thaw cycles (Figure 5) in terms of air temperature of the Ny-Alesund region for 6 years, average and range of annual freeze-thaw cycle was 52 and 33-62, respectively. The 900 freeze-thaw cycles implemented in this study aimed to conservatively simulate 14.5-27.3 years freeze-thaw cycles considering annual freeze-thaw cycle of 33-62 of the Ny-Alesund region. However, severe conditions of the experiment conducted in laboratory induce more freeze-thaw weathering of rocks as the rock samples are more saturated and typically smaller in sizes compared with rocks in nature state. Smaller sizes of rocks result in higher rock surface area per rock mass. The increased rock surface area per rock mass accelerates freeze-thaw weathering due to the increase exposal of heat changes on rock surfaces. Harsh environments in terms of high temperature change, wind, and salty water of the shore of the Ny-Alesund region, from which rock samples are obtained, influence the crystallization of salt under coastal weather conditions.  
Despite of many other factors describing discrepancy between nature and laboratory conditions, reasonable estimation of freeze-thaw weathering cycle and change of physical properties. Proper estimation of these characteristics enables the prediction of durability and remaining time to repair rock-related structures against freeze-thaw rock weathering.